Science.gov

Sample records for air turbulence cat

  1. Observation and Modeling of Clear Air Turbulence (CAT) over Europe

    NASA Astrophysics Data System (ADS)

    Sprenger, M.; Mayoraz, L.; Stauch, V.; Sharman, B.; Polymeris, J.

    2012-04-01

    CAT represents a very relevant phenomenon for aviation safety. It can lead to passenger injuries, causes an increase in fuel consumption and, under severe intensity, can involve structural damages to the aircraft. The physical processes causing CAT remain at present not fully understood. Moreover, because of its small scale, CAT cannot be represented in numerical weather prediction (NWP) models. In this study, the physical processes related to CAT and its representation in NWP models is further investigated. First, 134 CAT events over Europe are extracted from a flight monitoring data base (FDM), run by the SWISS airline and containing over 100'000 flights. The location, time, and meteorological parameters along the turbulent spots are analysed. Furthermore, the 7-km NWP model run by the Swiss National Weather Service (Meteoswiss) is used to calculate model-based CAT indices, e.g. Richardson number, Ellrod & Knapp turbulence index and a complex/combined CAT index developed at NCAR. The CAT indices simulated with COSMO-7 is then compared to the observed CAT spots, hence allowing to assess the model's performance, and potential use in a CAT warning system. In a second step, the meteorological conditions associated with CAT are investigated. To this aim, CAT events are defined as coherent structures in space and in time, i.e. their dimension and life cycle is studied, in connection with jet streams and upper-level fronts. Finally, in a third step the predictability of CAT is assessed, by comparing CAT index predictions based on different lead times of the NWP model COSMO-7

  2. Distinguishing between CAT and non-CAT areas by use of discriminant function analysis. [clear air turbulence

    NASA Technical Reports Server (NTRS)

    Clark, T. L.; Scoggins, J. R.; Cox, R. E.

    1974-01-01

    The investigation considered is concerned with a method in which a statistical approach is employed to determine algebraic functions involving selected synoptic-scale parameters which would indicate areas and altitudes of CAT in the stratosphere over the western U.S. The statistical approach selected is based on discriminant function analysis. The functions are determined from combinations of synoptic-scale parameters and stratospheric turbulence data. It was found in the investigation that there is a relationship between selected combinations of synoptic-scale parameters of the upper troposphere and lower stratosphere and stratospheric clear-air turbulence.

  3. Clear air turbulence forecasting techniques

    NASA Technical Reports Server (NTRS)

    Keller, J. L.

    1980-01-01

    A method to improve clear air turbulence (CAT) forecasting by more effectively using the currently operational rawinsonde (RW) system is discussed. The method is called the Diagnostic Richardson Number Tendency (DRT) technique. The technique does not attempt to use the RW as a direct detector of the turbulent motion or even of the CAT mechanism structure but rather senses the synoptic scale centers of action which provide the energy to the CAT mechanism at the mesoscale level. The DRT algorithm is deterministic rather than statistical in nature, using the hydrodynamic equations (equations of motion) relevant to the synoptic scale. However, interpretation, by necessity, is probabilistic. What is most important with respect to its operational implementation is that this method uses the same input data as currently used by the operational National Meteorological Center prognostic models.

  4. Lockheed Electra - animation showing air turbulence detection

    NASA Technical Reports Server (NTRS)

    1999-01-01

    On Mar. 24, 1998, an L-188 Electra aircraft owned by the National Science Foundation, Arlington, Virginia, and operated by the National Center for Atmospheric Research, Boulder, Colorado, flew near Boulder with an Airborne Coherent LiDAR (Light Detection and Ranging) for Advanced In-flight Measurement. This aircraft was on its first flight to test its ability to detect previously invisible forms of clear air turbulence. Coherent Technologies Inc., Lafayette, Colorado, built the LiDAR device for the NASA Dryden Flight Research Center, Edwards, California. NASA Dryden participated in the effort as part of the NASA Aviation Safety Program, for which the lead center was Langley Research Center, Hampton, Virginia. Results of the test indicated that the device did successfully detect the clear air turbulence. Computer animation of the clear air turbulence (CAT) detection system known as the 'Airborne Coherent LiDAR for Advanced In-flight Measurement' was tested aboard the National Science Foundation L-188 Lockheed Electra.

  5. The 1979 Clear Air Turbulence Flight Test Program

    NASA Technical Reports Server (NTRS)

    Weaver, E. A.; Ehernberger, L. J.; Gary, B. L.; Kurkowski, R. L.; Kuhn, P. M.; Stearns, L. P.

    1981-01-01

    The flight experiments for clear air turbulence (CAT) detection and measurement concepts are described. The test were conducted over the western part of the United States during the winter season of 1979 aboard NASA's Galileo 2 flying laboratory. A carbon dioxide pulsed Doppler lidar and an infrared radiometer were tested for the remote detection and measurement of CAT. Two microwave radiometers were evaluated for their ability to provide encounter warning and altitude avoidance information.

  6. Clear air turbulence avoidance using an airborne microwave radiometer

    NASA Technical Reports Server (NTRS)

    Gary, B. L.

    1984-01-01

    The avoidance of Clear Air Turbulence (CAT) is theoretically possible by selecting flight levels that are a safe distance from the tropopause and inversion layers. These favored sites for CAT generation can be located by an 'airborne microwave radiometer' (AMR) passive sensor system that measures altitude temperature profiles. A flight evaluation of the AMR sensor shows that most CAT could be avoided by following sensor-based advisories. Some limitations still exist for any hypothetical use of the sensor. The principal need is to augment the sensor's 'where' advisories to include useful 'when' forecasts.

  7. The physical and empirical basis for a specific clear-air turbulence risk index

    NASA Technical Reports Server (NTRS)

    Keller, J. L.

    1986-01-01

    The fundamental emphasis of this research was to develop a technique which would be a significant improvement over those currently used for flight planning to avoid clear air turbulence (CAT). The technique should, ideally, be both quantitative in determining potential intensity and specific in locating regions of relatively high risk. Furthermore, it should not rely on specialized data but be functional using the currently available rawinsonde observation (raob) system. Encouraging results documented in an earlier investigation were considered compelling enough to warrant a closer look into the possibilities of a Specific Clear Air Turbulence Risk (SCATR) index approach to the clear air turbulence problem. Unlike that research, which considered sustained periods of flight in light to moderate clear air turbulence, this study focuses on several cases of documented severe CAT. Results of these case studies suggest that a SCATR index is not an unrealizable goal and that uses of such an index, event in its current prototype level of development, are also apparent.

  8. Meteorological and operational aspects of 46 clear air turbulence sampling missions with an instrument B-57B aircraft. Volume 1: Program summary

    NASA Technical Reports Server (NTRS)

    Davis, R. E.; Champine, R. A.; Ehernberger, L. J.

    1979-01-01

    The results of 46 clear air turbulence (CAT) probing missions conducted with an extensively instrumented B-57B aircraft are summarized. Turbulence samples were obtained under diverse conditions including mountain waves, jet streams, upper level fronts and troughs, and low altitude mechanical and thermal turbulence. CAT was encouraged on 20 flights comprising 77 data runs. In all, approximately 4335 km were flown in light turbulence, 1415 km in moderate turbulence, and 255 km in severe turbulence during the program. The flight planning, operations, and turbulence forecasting aspects conducted with the B-57B aircraft are presented.

  9. Forecasting of Clear Air Turbulence using a Diagnostic Richardson Number Tendency formulation

    NASA Technical Reports Server (NTRS)

    Keller, J. L.; Haines, P. A.

    1981-01-01

    The results of several case studies of Clear Air Turbulence (CAT) using the Diagnostic Richardson Number Tendency (DRT) formulation are highlighted. The performance of this technique in resolving regions of documented CAT encounters is encouraging. Its operational adaptability seems particularly attractive in that the input data can be supplied by the currently operational Rawinsonde system. A CAT index is calculated deterministically, sensing synoptic-scale changes in static stability and vertical wind shear conducive for supporting meso-scale CAT layers. This index reveals volumes of the troposphere which act as 'source regions' of Kelvin-Helmholtz instabilities. The results suggest that these regions are particularly efficient with respect to the synoptic/meso-scale energetical coupling necessary for supporting significantly turbulent layers. The output highlights specific regions of the atmosphere which can be interpreted operationally in terms of CAT-encounter probabilities.

  10. Meteorological and operational aspects of 46 clear air turbulent sampling missions with an instrumented B-57B aircraft. Volume 2, appendix C: Turbulence missions

    NASA Technical Reports Server (NTRS)

    Waco, D. E.

    1979-01-01

    The results of 46 clear air turbulence (CAT) probing missions conducted with an extensively instrumented B-57B aircraft are summarized from a meteorological viewpoint in a two-volume technical memorandum. The missions were part of the NASA Langley Research Center's MAT (Measurement of Atmospheric Turbulence) program, which was conducted between March 1974, and September 1975, at altitudes ranging up to 15 km. Turbulence samples were obtained under diverse conditions including mountain waves, jet streams, upper level fronts and troughs, and low altitude mechanical and thermal turbulence. CAT was encountered on 20 flights comprising 77 data runs. In all, approximately 4335 km were flown in light turbulence, 1415 km in moderate turbulence, and 255 km in severe turbulence during the program.

  11. CATS-based Air Traffic Controller Agents

    NASA Technical Reports Server (NTRS)

    Callantine, Todd J.

    2002-01-01

    This report describes intelligent agents that function as air traffic controllers. Each agent controls traffic in a single sector in real time; agents controlling traffic in adjoining sectors can coordinate to manage an arrival flow across a given meter fix. The purpose of this research is threefold. First, it seeks to study the design of agents for controlling complex systems. In particular, it investigates agent planning and reactive control functionality in a dynamic environment in which a variety perceptual and decision making skills play a central role. It examines how heuristic rules can be applied to model planning and decision making skills, rather than attempting to apply optimization methods. Thus, the research attempts to develop intelligent agents that provide an approximation of human air traffic controller behavior that, while not based on an explicit cognitive model, does produce task performance consistent with the way human air traffic controllers operate. Second, this research sought to extend previous research on using the Crew Activity Tracking System (CATS) as the basis for intelligent agents. The agents use a high-level model of air traffic controller activities to structure the control task. To execute an activity in the CATS model, according to the current task context, the agents reference a 'skill library' and 'control rules' that in turn execute the pattern recognition, planning, and decision-making required to perform the activity. Applying the skills enables the agents to modify their representation of the current control situation (i.e., the 'flick' or 'picture'). The updated representation supports the next activity in a cycle of action that, taken as a whole, simulates air traffic controller behavior. A third, practical motivation for this research is to use intelligent agents to support evaluation of new air traffic control (ATC) methods to support new Air Traffic Management (ATM) concepts. Current approaches that use large, human

  12. Development of CO2 laser Doppler instrumentation for detection of clear air turbulence, volume 1

    NASA Technical Reports Server (NTRS)

    Harris, C. E.; Jelalian, A. V.

    1979-01-01

    Modification, construction, test and operation of an advanced airborne carbon dioxide laser Doppler system for detecting clear air turbulence are described. The second generation CAT program and those auxiliary activities required to support and verify such a first-of-a-kind system are detailed: aircraft interface; ground and flight verification tests; data analysis; and laboratory examinations.

  13. Flight tests of a clear-air turbulence alerting system. [infrared radiometers

    NASA Technical Reports Server (NTRS)

    Kurkowski, R. L.; Kuhn, P. M.; Stearns, L. P.

    1981-01-01

    The detection of clear-air turbulence (CAT) ahead of an aircraft in real-time by an infrared (IR) radiometer is discussed. It is noted that the alter time and reliability depend on the band-pass of the IR filter used and on the altitude of the aircraft. Results of flights tests indicate that a bandpass of 20 to 40 microns appears optimal for altering the aircraft crew to CAT at times before encounter of 2 to 9 min. Alert time increases with altitude, as the atmospheric absorption determining the horizontal weighting is reduced.

  14. Broadband Phase Spectroscopy over Turbulent Air Paths.

    PubMed

    Giorgetta, Fabrizio R; Rieker, Gregory B; Baumann, Esther; Swann, William C; Sinclair, Laura C; Kofler, Jon; Coddington, Ian; Newbury, Nathan R

    2015-09-04

    Broadband atmospheric phase spectra are acquired with a phase-sensitive dual-frequency-comb spectrometer by implementing adaptive compensation for the strong decoherence from atmospheric turbulence. The compensation is possible due to the pistonlike behavior of turbulence across a single spatial-mode path combined with the intrinsic frequency stability and high sampling speed associated with dual-comb spectroscopy. The atmospheric phase spectrum is measured across 2 km of air at each of the 70,000 comb teeth spanning 233  cm(-1) across hundreds of near-infrared rovibrational resonances of CO(2), CH(4), and H(2)O with submilliradian uncertainty, corresponding to a 10(-13) refractive index sensitivity. Trace gas concentrations extracted directly from the phase spectrum reach 0.7 ppm uncertainty, demonstrated here for CO(2). While conventional broadband spectroscopy only measures intensity absorption, this approach enables measurement of the full complex susceptibility even in practical open path sensing.

  15. Broadband Phase Spectroscopy over Turbulent Air Paths

    NASA Astrophysics Data System (ADS)

    Giorgetta, Fabrizio R.; Rieker, Gregory B.; Baumann, Esther; Swann, William C.; Sinclair, Laura C.; Kofler, Jon; Coddington, Ian; Newbury, Nathan R.

    2015-09-01

    Broadband atmospheric phase spectra are acquired with a phase-sensitive dual-frequency-comb spectrometer by implementing adaptive compensation for the strong decoherence from atmospheric turbulence. The compensation is possible due to the pistonlike behavior of turbulence across a single spatial-mode path combined with the intrinsic frequency stability and high sampling speed associated with dual-comb spectroscopy. The atmospheric phase spectrum is measured across 2 km of air at each of the 70 000 comb teeth spanning 233 cm-1 across hundreds of near-infrared rovibrational resonances of CO2 , CH4 , and H2O with submilliradian uncertainty, corresponding to a 10-13 refractive index sensitivity. Trace gas concentrations extracted directly from the phase spectrum reach 0.7 ppm uncertainty, demonstrated here for CO2 . While conventional broadband spectroscopy only measures intensity absorption, this approach enables measurement of the full complex susceptibility even in practical open path sensing.

  16. Airborne forward-pointing UV Rayleigh lidar for remote clear air turbulence detection: system design and performance.

    PubMed

    Vrancken, Patrick; Wirth, Martin; Ehret, Gerhard; Barny, Hervé; Rondeau, Philippe; Veerman, Henk

    2016-11-10

    A high-performance airborne UV Rayleigh lidar system was developed within the European project DELICAT. With its forward-pointing architecture, it aims at demonstrating a novel detection scheme for clear air turbulence (CAT) for an aeronautics safety application. Due to its occurrence in clear and clean air at high altitudes (aviation cruise flight level), this type of turbulence evades microwave radar techniques and in most cases coherent Doppler lidar techniques. The present lidar detection technique relies on air density fluctuation measurement and is thus independent of backscatter from hydrometeors and aerosol particles. The subtle air density fluctuations caused by the turbulent air flow demand exceptionally high stability of the setup and in particular of the detection system. This paper describes an airborne test system for the purpose of demonstrating this technology and turbulence detection method: a high-power UV Rayleigh lidar system is installed on a research aircraft in a forward-looking configuration for use in cruise flight altitudes. Flight test measurements demonstrate this unique lidar system being able to resolve air density fluctuations occurring in light-to-moderate CAT at 5 km or moderate CAT at 10 km distance. A scaling of the determined stability and noise characteristics shows that such performance is adequate for an application in commercial air transport.

  17. Tentative detection of clear-air turbulence using a ground-based Rayleigh lidar.

    PubMed

    Hauchecorne, Alain; Cot, Charles; Dalaudier, Francis; Porteneuve, Jacques; Gaudo, Thierry; Wilson, Richard; Cénac, Claire; Laqui, Christian; Keckhut, Philippe; Perrin, Jean-Marie; Dolfi, Agnès; Cézard, Nicolas; Lombard, Laurent; Besson, Claudine

    2016-05-01

    Atmospheric gravity waves and turbulence generate small-scale fluctuations of wind, pressure, density, and temperature in the atmosphere. These fluctuations represent a real hazard for commercial aircraft and are known by the generic name of clear-air turbulence (CAT). Numerical weather prediction models do not resolve CAT and therefore provide only a probability of occurrence. A ground-based Rayleigh lidar was designed and implemented to remotely detect and characterize the atmospheric variability induced by turbulence in vertical scales between 40 m and a few hundred meters. Field measurements were performed at Observatoire de Haute-Provence (OHP, France) on 8 December 2008 and 23 June 2009. The estimate of the mean squared amplitude of bidimensional fluctuations of lidar signal showed excess compared to the estimated contribution of the instrumental noise. This excess can be attributed to atmospheric turbulence with a 95% confidence level. During the first night, data from collocated stratosphere-troposphere (ST) radar were available. Altitudes of the turbulent layers detected by the lidar were roughly consistent with those of layers with enhanced radar echo. The derived values of turbulence parameters Cn2 or CT2 were in the range of those published in the literature using ST radar data. However, the detection was at the limit of the instrumental noise and additional measurement campaigns are highly desirable to confirm these initial results. This is to our knowledge the first successful attempt to detect CAT in the free troposphere using an incoherent Rayleigh lidar system. The built lidar device may serve as a test bed for the definition of embarked CAT detection lidar systems aboard airliners.

  18. CATS - A process-based model for turbulent turbidite systems at the reservoir scale

    NASA Astrophysics Data System (ADS)

    Teles, Vanessa; Chauveau, Benoît; Joseph, Philippe; Weill, Pierre; Maktouf, Fakher

    2016-09-01

    The Cellular Automata for Turbidite systems (CATS) model is intended to simulate the fine architecture and facies distribution of turbidite reservoirs with a multi-event and process-based approach. The main processes of low-density turbulent turbidity flow are modeled: downslope sediment-laden flow, entrainment of ambient water, erosion and deposition of several distinct lithologies. This numerical model, derived from (Salles, 2006; Salles et al., 2007), proposes a new approach based on the Rouse concentration profile to consider the flow capacity to carry the sediment load in suspension. In CATS, the flow distribution on a given topography is modeled with local rules between neighboring cells (cellular automata) based on potential and kinetic energy balance and diffusion concepts. Input parameters are the initial flow parameters and a 3D topography at depositional time. An overview of CATS capabilities in different contexts is presented and discussed.

  19. Bartonella spp. in cats from Buenos Aires, Argentina.

    PubMed

    Cicuttin, Gabriel L; Brambati, Diego F; De Gennaro, María F; Carmona, Fernando; Isturiz, María L; Pujol, Laura E; Belerenian, Guillermo C; Gil, Horacio

    2014-01-10

    In Argentina, data on the presence of members of the genus Bartonella is scarce. To increase knowledge about these zoonotic pathogens in this country, the presence and variability of Bartonella spp. was investigated in cats and dogs from Buenos Aires. Bartonella spp. was detected in 17.8% of cats, while all dogs tested negative by PCR and Reverse Line Blot. B. henselae was the most frequent species, being detected in 11.9% (14/101), while B. clarridgeiae was found in only 5.9% (6/101) of the cats. Afterwards, B. henselae isolates and positive blood samples were characterized by Multiple Locus Sequence Typing (MLST) and Multiple Locus Variable Number Tandem Repeats Analysis (MLVA). As result, four different MLST sequence types (ST) and eight MLVA profiles were identified. ST 1 was the most frequent variant found in cats, followed by ST 8. Interestingly, some of the MLVA profiles that were detected in this study have been previously associated with human disease, and represents a potential risk of infection. Veterinarians and physicians should consider the presence of these emerging pathogens in their diagnostic routine.

  20. Cats

    MedlinePlus

    ... Patients Infants and Young Children Publications & Materials Announcements Cats Recommend on Facebook Tweet Share Compartir Overview Diseases ... hand washing whenever you play or work with cats Wash your hands with soap and running water ...

  1. A domain analysis approach to clear-air turbulence forecasting using high-density in-situ measurements

    NASA Astrophysics Data System (ADS)

    Abernethy, Jennifer A.

    Pilots' ability to avoid clear-air turbulence (CAT) during flight affects the safety of the millions of people who fly commercial airlines and other aircraft, and turbulence costs millions in injuries and aircraft maintenance every year. Forecasting CAT is not straightforward, however; microscale features like the turbulence eddies that affect aircraft (100m) are below the current resolution of operational numerical weather prediction (NWP) models, and the only evidence of CAT episodes, until recently, has been sparse, subjective reports from pilots known as PIREPs. To forecast CAT, researchers use a simple weighted sum of top-performing turbulence indicators derived from NWP model outputs---termed diagnostics---based on their agreement with current PIREPs. However, a new, quantitative source of observation data---high-density measurements made by sensor equipment and software on aircraft, called in-situ measurements---is now available. The main goal of this thesis is to develop new data analysis and processing techniques to apply to the model and new observation data, in order to improve CAT forecasting accuracy. This thesis shows that using in-situ data improves forecasting accuracy and that automated machine learning algorithms such as support vector machines (SVM), logistic regression, and random forests, can match current performance while eliminating almost all hand-tuning. Feature subset selection is paired with the new algorithms to choose diagnostics that predict well as a group rather than individually. Specializing forecasts and choice of diagnostics by geographic region further improves accuracy because of the geographic variation in turbulence sources. This work uses random forests to find climatologically-relevant regions based on these variations and implements a forecasting system testbed which brings these techniques together to rapidly prototype new, regionalized versions of operational CAT forecasting systems.

  2. The physical and empirical basis for a specific clear-air turbulence risk index

    NASA Technical Reports Server (NTRS)

    Keller, J. L.

    1985-01-01

    An improved operational CAT detection and forecasting technique is developed and detailed. This technique is the specific clear air turbulence risk (SCATR) index. This index shows some promising results. The improvements seen using hand analyzed data, as a result of the more realistic representation of the vertical shear of the horizontal wind, are also realized in the data analysis used in the PROFS/CWP application. The SCATR index should improve as database enhancements such as profiler and VAS satellite data, which increase the resolution in space and time, are brought into even more sophisticated objective analysis schemes.

  3. Using Indirect Turbulence Measurements for Real-Time Parameter Estimation in Turbulent Air

    NASA Technical Reports Server (NTRS)

    Martos, Borja; Morelli, Eugene A.

    2012-01-01

    The use of indirect turbulence measurements for real-time estimation of parameters in a linear longitudinal dynamics model in atmospheric turbulence was studied. It is shown that measuring the atmospheric turbulence makes it possible to treat the turbulence as a measured explanatory variable in the parameter estimation problem. Commercial off-the-shelf sensors were researched and evaluated, then compared to air data booms. Sources of colored noise in the explanatory variables resulting from typical turbulence measurement techniques were identified and studied. A major source of colored noise in the explanatory variables was identified as frequency dependent upwash and time delay. The resulting upwash and time delay corrections were analyzed and compared to previous time shift dynamic modeling research. Simulation data as well as flight test data in atmospheric turbulence were used to verify the time delay behavior. Recommendations are given for follow on flight research and instrumentation.

  4. Ignition of hydrogen/air mixing layer in turbulent flows

    SciTech Connect

    Im, H.G.; Chen, J.H.; Law, C.K.

    1998-03-01

    Autoignition of a scalar hydrogen/air mixing layer in homogeneous turbulence is studied using direct numerical simulation. An initial counterflow of unmixed nitrogen-diluted hydrogen and heated air is perturbed by two-dimensional homogeneous turbulence. The temperature of the heated air stream is chosen to be 1,100 K which is substantially higher than the crossover temperature at which the rates of the chain branching and termination reactions become equal. Three different turbulence intensities are tested in order to assess the effect of the characteristic flow time on the ignition delay. For each condition, a simulation without heat release is also performed. The ignition delay determined with and without heat release is shown to be almost identical up to the point of ignition for all of the turbulence intensities tested, and the predicted ignition delays agree well within a consistent error band. It is also observed that the ignition kernel always occurs where hydrogen is focused, and the peak concentration of HO{sub 2} is aligned well with the scalar dissipation rate. The dependence of the ignition delay on turbulence intensity is found to be nonmonotonic. For weak to moderate turbulence the ignition is facilitated by turbulence via enhanced mixing, while for stronger turbulence, whose timescale is substantially smaller than the ignition delay, the ignition is retarded due to excessive scalar dissipation, and hence diffusive loss, at the ignition location. However, for the wide range of initial turbulence fields studied, the variation in ignition delay due to the corresponding variation in turbulence intensity appears to be quite small.

  5. A Numerical Study on Clear-Air Turbulence Occurred in South Korea on April 2, 2007

    NASA Astrophysics Data System (ADS)

    Kim, J.-H.; Chun, H.-Y.

    2009-04-01

    On 2 April 2007, 12 clear-air turbulence (CAT) cases were reported from pilot report (PIREP), including seven moderate-or-greater intensity, in Korea during 8 hours from 00 to 08 UTC. Those CAT encounters were distributed in three different regions in Korean peninsula: western coast, eastern mountain area, and Jeju Island. Characteristics and possible mechanisms of those CAT events in the different regions are investigated using a non-hydrostatic and fully compressible numerical model Weather Research Forecast (WRF). The model configuration consisted of five nested domains in the East Asian region with the finest 1-km horizontal grid spacing. Simulated wind and temperature fields on 27-km coarse domain at 00 UTC 4 April agree reasonably well with those observed in rawinsondes launched at 5 stations in Korea. In synoptic features, strong jet stream flows from the west to the east over Korean peninsula, and upper-level frontogenesis associated with strong meridional temperature gradients is intensified. Especially, deep tropopause folding is developed along strong jet core and upper-level front, and it is well coincident with the CAT encounters near the western coast region. Mountain waves over the eastern mountain area propagate to the region below the jet stream in which the static stability is relatively weak and vertical wind shear is strong. The mountain waves are amplified with height and locally breakdown near the CAT encounters in the eastern mountain area. Trapped lee waves are produced by flow over Mt. Halla in Jeju Island due to significant change of background stability passing through the isolated mountain. These lee waves perturb local wind and stability, promoting development of reduced Richardson number conducive to CAT encounters near Jeju Island. Detailed simulation results will be presented in the conference.

  6. Turbulence Effects on Open Air Multipaths.

    DTIC Science & Technology

    1981-05-01

    RECIPIENT- CATALOG NJM-.rl ASL-TR-0086 T-,’ 101 )- , . 4. TITLE (id Subttle) S. TT!E O F REPORT 6 tiEre)1, UCVERED TURBULENCE LFFECTS ON OPEN R D Final...was comparable in terms of beam epaiO.or3. litter, and wander to tn f]3riJation experienced in a sealed levacrab> absoroDon c-11. Th-i wa’ indeed...Measurements," Rev Sci Instrum, 50:86 ’ D . L. Fried, 1966, "Limiting Resolution Looking Down Through the Atmosphere," J Opt Soc Am, 56:1380 8 POWER METER

  7. Multiscale turbulence effects in supersonic jets exhausting into still air

    NASA Technical Reports Server (NTRS)

    Abdol-Hamid, Khaled S.; Wilmoth, Richard G.

    1987-01-01

    A modified version of the multiscale turbulence model of Hanjalic has been applied to the problem of supersonic jets exhausting into still air. In particular, the problem of shock-cell decay through turbulent interaction with the mixing layer has been studied for both mildly interacting and strongly resonant jet conditions. The modified Hanjalic model takes into account the nonequilibrium energy transfer between two different turbulent spectral scales. The turbulence model was incorporated into an existing shock-capturing, parabolized Navier-Stokes computational model in order to perform numerical experiments. The results show that the two-scale turbulence model provides significant improvement over one-scale models in the prediction of plume shock structure for underexpanded supersonic (Mach 2) and sonic (Mach 1) jets. For the supersonic jet, excellent agreement with experiment was obtained for the centerline shock-cell pressure decay up to 40 jet radii. For the sonic jet, the agreement with experiment was not so good, but the two-scale model still showed significant improvement over the one-scale model. It is shown that by relating some of the coefficients in the turbulent-transport equations to the relative time scale for transfer of energy between scales the two-scale model can provide predictions that bound the measured shock-cell decay rate for the sonic jet.

  8. Additional research on instabilities in atmospheric flow systems associated with clear air turbulence

    NASA Technical Reports Server (NTRS)

    Stoeffler, R. C.

    1972-01-01

    Analytical and experimental fluid mechanics studies were conducted to investigate instabilities in atmospheric flow systems associated with clear air turbulence. The experimental portion of the program was conducted using an open water channel which allows investigation of flows having wide ranges of shear and density stratification. The program was primarily directed toward studies of the stability of straight, stratified shear flows with particular emphasis on the effects of velocity profile on stability; on studies of three-dimensional effects on the breakdown region in shear layers; on the the interaction of shear flows with long-wave length internal waves; and on the stability of shear flows consisting of adjacent stable layers. The results of these studies were used to evaluate methods used in analyses of CAT encounters in the atmosphere involving wave-induced shear layer instabilities of the Kelvin-Helmholta type. A computer program was developed for predicting shear-layer instability and CAT induced by mountain waves. This technique predicts specific altitudes and locations where CAT would be expected.

  9. Generating and controlling homogeneous air turbulence using random jet arrays

    NASA Astrophysics Data System (ADS)

    Carter, Douglas; Petersen, Alec; Amili, Omid; Coletti, Filippo

    2016-12-01

    The use of random jet arrays, already employed in water tank facilities to generate zero-mean-flow homogeneous turbulence, is extended to air as a working fluid. A novel facility is introduced that uses two facing arrays of individually controlled jets (256 in total) to force steady homogeneous turbulence with negligible mean flow, shear, and strain. Quasi-synthetic jet pumps are created by expanding pressurized air through small straight nozzles and are actuated by fast-response low-voltage solenoid valves. Velocity fields, two-point correlations, energy spectra, and second-order structure functions are obtained from 2D PIV and are used to characterize the turbulence from the integral-to-the Kolmogorov scales. Several metrics are defined to quantify how well zero-mean-flow homogeneous turbulence is approximated for a wide range of forcing and geometric parameters. With increasing jet firing time duration, both the velocity fluctuations and the integral length scales are augmented and therefore the Reynolds number is increased. We reach a Taylor-microscale Reynolds number of 470, a large-scale Reynolds number of 74,000, and an integral-to-Kolmogorov length scale ratio of 680. The volume of the present homogeneous turbulence, the largest reported to date in a zero-mean-flow facility, is much larger than the integral length scale, allowing for the natural development of the energy cascade. The turbulence is found to be anisotropic irrespective of the distance between the jet arrays. Fine grids placed in front of the jets are effective at modulating the turbulence, reducing both velocity fluctuations and integral scales. Varying the jet-to-jet spacing within each array has no effect on the integral length scale, suggesting that this is dictated by the length scale of the jets.

  10. The indoor air and asthma: the role of cat allergens

    PubMed Central

    Kelly, Libby A.; Erwin, Elizabeth A.; Platts-Mills, Thomas A. E.

    2012-01-01

    Purpose of review The objective is to discuss recent progress in our understanding of the role of the indoor environment in asthma, focusing on the special role of cat allergens. Recent findings Sensitization to Fel d 1 is the dominant event in inhalant responses to cat; however, there are also IgE responses to the lipocalin (Fel d 4), to cat albumin (Fel d 2), and to the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal) on cat IgA (Fel d 5w) and other molecules. The dose response and routes of sensitization for these allergens are now thought to be diverse. It is important to remember that exposure outside a house with a cat is sufficient to cause sensitization. Furthermore, the only solid evidence about a role in asthma relates to Fel d 1. Recently, it has been shown that tolerance associated with early exposure to cats can persist to age 18 and that IgE to alpha-gal (on cat IgA) is not related to asthma. In addition, a recent study of anti-IgE reinforces the evidence that IgE antibodies to indoor allergens make a major contribution to asthma severity. Summary Exposure to Fel d 1 in a home with a cat is far higher than the levels necessary to induce an allergic (IgE antibody) response. In keeping with that, children may develop tolerance, which can be long-lived. In addition, there is increasing evidence that IgE antibodies to an inhalant allergen, such as Fel d 1, dust mite, or cockroach, are causally related to lung inflammation and asthma. PMID:22081090

  11. Mode S and ADS-B as a Source of Clear-Air Turbulence Measurements

    NASA Astrophysics Data System (ADS)

    Kopeć, Jacek; Kwiatkowski, Kamil; de Haan, Siebren; Malinowski, Szymon

    2016-04-01

    Clear-Air Turbulence (CAT) beside being the most common cause for commercial aircraft incidents in the cruise phase is a complex physical phenomenon. CAT is an effect of various underlying physical mechanisms such as different kinds of hydrodynamic instabilities or large scale forcing. In order to properly understand and correctly forecast it one needs a significant amount of observation data. Up to date the best available observations are the in-situ EDR (from eddy dissipation rate - a measure of turbulence intensity). Those observations are reported every ~1 min of flight (roughly every 15 km). Yet their availability is limited by the willingness of the airlines to cooperate in adjusting on-board software. However there is a class of data that can be accessed more freely. In this communication we present and discuss a feasibility analysis of the three methods of processing Mode S/ADS-B messages into viable turbulence measurements. The Mode S/ADS-B messages are unrestricted navigational data broadcast by most of the commercial aircraft. The unique characteristic of this data is a very high temporal resolution. This allows to employ processing which results in obtaining turbulence information characterized by spatial resolution comparable with the best available data sources. Moreover due to using Mode-S/ASS-B data, the number of aircraft that are providing observations increases significantly. The methods are either using simple positioning information available in the ADS-B or high-resolution wind information from the Mode S. The paper is largely based on the results of the methods application to the data originating from DELICAT flight campaign that took place in 2013. The flight campaign was conducted using NLR operated Cessna Citation II. The reference Mode-S/ADS-B data partly overlapping with the research flights were supplied by the KNMI. Analysis shows very significant potential of the Mode-S wind based methods. J. M. Kopeć, K. Kwiatkowski, S. de Haan, and

  12. Discovery about temperature fluctuations in turbulent air flows

    NASA Astrophysics Data System (ADS)

    1985-02-01

    The law of spatial fluctuations of temperature in a turbulent flow in the atmosphere was studied. The turbulent movement of air in the atmosphere manifests itself in random changes in wind velocity and in the dispersal of smoke. If a miniature thermometer with sufficient sensitivity and speed of response were placed in a air flow, its readings would fluctuate chaotically against the background of average temperature. This is Characteristic of practically every point of the flow. The temperature field forms as a result of the mixing of the air. A method using the relation of the mean square of the difference in temperatures of two points to the distance between these points as the structural characteristic of this field was proposed. It was found that the dissipation of energy in a flow and the equalization of temperatures are connected with the breaking up of eddies in a turbulent flow into smaller ones. Their energy in turn is converted into heat due to the viscosity of the medium. The law that has been discovered makes for a much broader field of application of physical methods of analyzing atmospheric phenomena.

  13. Wake Turbulence: An Obstacle to Increased Air Traffic Capacity

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Wingtip vortices were first described by British aerodynamicist F.W. Lanchester in 1907. A product of lift on a finite-span wing, these counterrotating masses of air trail behind an aircraft, gradually diffusing while convecting downward and moving about under mutual induction and the influence of wind and stratification. Should a smaller aircraft happen to be following the first aircraft, it could be buffeted and even flipped if it flew into the vortex, with dangerous consequences. Given the amount of air traffic in 1907, the wake vortex hazard was not initially much of a concern. The demand for air transportation continues to increase, and it is estimated that demand could double or even triple by 2025. One factor in the capacity of the air transportation system is wake turbulence and the consequent separation distances that must be maintained between aircraft to ensure safety.

  14. Calibration of NASA Turbulent Air Motion Measurement System

    NASA Technical Reports Server (NTRS)

    Barrick, John D. W.; Ritter, John A.; Watson, Catherine E.; Wynkoop, Mark W.; Quinn, John K.; Norfolk, Daniel R.

    1996-01-01

    A turbulent air motion measurement system (TAMMS) was integrated onboard the Lockheed 188 Electra airplane (designated NASA 429) based at the Wallops Flight Facility in support of the NASA role in global tropospheric research. The system provides air motion and turbulence measurements from an airborne platform which is capable of sampling tropospheric and planetary boundary-layer conditions. TAMMS consists of a gust probe with free-rotating vanes mounted on a 3.7-m epoxy-graphite composite nose boom, a high-resolution inertial navigation system (INS), and data acquisition system. A variation of the tower flyby method augmented with radar tracking was implemented for the calibration of static pressure position error and air temperature probe. Additional flight calibration maneuvers were performed remote from the tower in homogeneous atmospheric conditions. System hardware and instrumentation are described and the calibration procedures discussed. Calibration and flight results are presented to illustrate the overall ability of the system to determine the three-component ambient wind fields during straight and level flight conditions.

  15. Effects of pressure on syngas/air turbulent nonpremixed flames

    NASA Astrophysics Data System (ADS)

    Lee, Bok Jik; Im, Hong G.; Ciottoli, Pietro Paolo; Valorani, Mauro

    2016-11-01

    Large eddy simulations (LES) of turbulent non-premixed jet flames were conducted to investigate the effects of pressure on the syngas/air flame behavior. The software to solve the reactive Navier-Stokes equations was developed based on the OpenFOAM framework, using the YSLFM library for the flamelet-based chemical closure. The flamelet tabulation is obtained by means of an in-house code designed to solve unsteady flamelets of both ideal and real fluid mixtures. The validation of the numerical setup is attained by comparison of the numerical results with the Sandia/ETH-Zurich experimental database of the CO/H2/N2 non-premixed, unconfined, turbulent jet flame, referred to as "Flame A". Two additional simulations, at pressure conditions of 2 and 5 atm, are compared and analyzed to unravel computational and scientific challenges in characterizing turbulent flames at high pressures. A set of flamelet solutions, representative of the jet flames under review, are analyzed following a CSP approach. In particular, the Tangential Stretching Rate (TSR), representing the reciprocal of the most energetic time scale associated with the chemical source term, and its extension to reaction-diffusion systems (extended TSR), are adopted.

  16. Further experiments on the stability of laminar and turbulent hydrogen-air flames at reduced pressures

    NASA Technical Reports Server (NTRS)

    Fine, Burton

    1957-01-01

    Stability limits for laminar and turbulent hydrogen-air burner flames were measured as a function of pressure, burner diameter, and composition. On the basis of a simple flame model, turbulent flashback involved a smaller effective penetration distance than laminar flashback. No current theoretical treatment predicts the observed pressure and diameter dependence of laminar and turbulent blowoff.

  17. Microwave temperature profiler for clear air turbulence prediction

    NASA Technical Reports Server (NTRS)

    Gary, Bruce L. (Inventor)

    1992-01-01

    A method is disclosed for determining Richardson Number, Ri, or its reciprocal, RRi, for clear air prediction using measured potential temperature and determining the vertical gradient of potential temperature, d(theta)/dz. Wind vector from the aircraft instrumentation versus potential temperature, dW/D(theta), is determined and multiplies by d(theta)/dz to obtain dW/dz. Richardson number or its reciprocal is then determined from the relationship Ri = K(d theta)/dz divided by (dW/dz squared) for use in detecting a trend toward a threshold value for the purpose of predicting clear air turbulence. Other equations for this basic relationship are disclosed together with the combination of other atmospheric observables using multiple regression techniques.

  18. Clear turbulence forecasting - Towards a union of art and science

    NASA Technical Reports Server (NTRS)

    Keller, J. L.

    1985-01-01

    The development of clear air turbulence (CAT) forecasting over the last several decades is reviewed in the context of empirical and theoretical research into the nature of nonconvective turbulence in the free atmosphere, particularly at jet stream levels. Various qualitative CAT forecasting techniques are examined, and prospects for an effective quantitative index to aid aviation meteorologists in jet stream level turbulence monitoring and forecasting are examined. Finally, the use of on-board sensors for short-term warning is discussed.

  19. CAT altitude avoidance system

    NASA Technical Reports Server (NTRS)

    Gary, B. L. (Inventor)

    1982-01-01

    A method and apparatus are provided for indicating the altitude of the tropopause or of an inversion layer wherein clear air turbulence (CAT) may occur, and the likely severity of any such CAT, includes directing a passive microwave radiometer on the aircraft at different angles with respect to the horizon. The microwave radiation measured at a frequency of about 55 GHz represents the temperature of the air at an ""average'' range of about 3 kilometers, so that the sine of the angle of the radiometer times 3 kilometers equals the approximate altitude of the air whose temperature is measured. A plot of altitude (with respect to the aircraft) versus temperature of the air at that altitude, can indicate when an inversion layer is present and can indicate the altitude of the tropopause or of such an inversion layer. The plot can also indicate the severity of any CAT in an inversion layer. If CAT has been detected in the general area, then the aircraft can be flown at an altitude to avoid the tropopause or inversion layer.

  20. Flow on Magnetizable Particles in Turbulent Air Streams. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Davey, K. R.

    1979-01-01

    The flow of magnetizable particles in a turbulent air stream in the presence of an imposed magnetic field and the phenomenon of drag reduction produced by the introduction of particles in turbulent boundary layer are investigated. The nature of the particle magnetic force is discussed and the inherent difference between electric and magnetic precipitation is considered. The incorporation of turbulent diffusion theory with an imposed magnetic migration process both with and without inertia effects is examined.

  1. Mitigating the Effects of Atmospheric Turbulence: Towards More Useful Micro Air Vehicles

    DTIC Science & Technology

    2010-07-18

    outdoor turbulent environment. 25 REFERENCES AND BIBLIOGRAPHY Abdulrahim M., Watkins S., Segal R . and Sheridan J., “Dynamic Sensitivity to...Shortis M., Loxton B., Segal R . and Bil C., “Turbulence in the Atmospheric Wind: A Limiting Factor in MAV Operations”, 24th Bristol Unmanned Air

  2. [A case of bat rabies in a cat in the province of Buenos Aires, Argentina].

    PubMed

    Amasino, C F; Gury Dohmen, F; de Gaetano, J; Mena Segura, C; Palazzolo, A

    2003-12-01

    In the Central Laboratory of Public Health in Buenos Aires, rabies was detected in a cat that was brought in for diagnosis by its owners. The animal, which was displaying symptoms of the furious form of the disease, had attacked three people in the rural area of Chascomús, near the Rio de la Plata. All three of the people who had been bitten received the necessary treatment. The diagnosis was made using the fluorescent antibody test and the inoculation of mice and the results were communicated to the Zoonoses Division of the Ministry of Health. The virus was then typed at the Institute Pasteur of Buenos Aires using monoclonal antibodies, where it was found to be antigenic variant 4 of serotype 1, i.e., the type of virus usually found in insectivorous bats. This area has been free of the canine variant since 1984. This is the first known case in the province of Buenos Aires of a cat becoming infected with this type of virus. It confirms that there is a link between the air and terrestrial cycles of rabies in this area.

  3. Filamentation of femtosecond laser pulse influenced by the air turbulence at various propagation distances

    NASA Astrophysics Data System (ADS)

    Hu, Yuze; Nie, Jinsong; Sun, Ke; Wang, Lei

    2017-01-01

    The spatial and temporal features of femtosecond laser filamentation, which are induced by a laser with power several times higher than the critical power, influenced by strong air turbulence at various propagation distances have been studied numerically. First, a strong turbulence occurring right before focal lens induces a few counter-balanced energy spikes which prevent the filament generation. Second, with the turbulence right before the filamentation, side filaments formed in the periphery towards the outside area leads the filament to be slightly short. Third, with the turbulence right after the lens, numerous energy spikes of the wave profile arise, but they will merge into one filament gradually, leading to a delayed filamentation onset and a shorter filamentation length. The deformation of temporal pulse shape become more sensitive and the supercontinuum (SC) can be weakened more significantly when strong turbulence takes place in air more previously.

  4. Coal air turbine {open_quotes}CAT{close_quotes} program invention 604. Fourth quarter project report, July 1995--September 1995

    SciTech Connect

    Foster-Pegg, R.W.

    1995-10-31

    A coal air turbine `CAT` generates electric power and heat from coal combustion. The purpose of this project is the conceptual design of a `CAT` plant, and to make a comparison of the capital cost and and cost of power and steam from the `CAT` plant with power produced by alternate plants at the same site. Three configurations investigated include: condensing plant utilizing coal fuel and a condenser tower, or river, for cooling; a cogeneration plant utilizing coal and a steam turbine; and a cogeneration plant utilizing steam export and injection with waste coal fuel.

  5. Turbulent Boundary Layer in High Rayleigh Number Convection in Air

    NASA Astrophysics Data System (ADS)

    du Puits, Ronald; Li, Ling; Resagk, Christian; Thess, André; Willert, Christian

    2014-03-01

    Flow visualizations and particle image velocimetry measurements in the boundary layer of a Rayleigh-Bénard experiment are presented for the Rayleigh number Ra =1.4×1010. Our visualizations indicate that the appearance of the flow structures is similar to ordinary (isothermal) turbulent boundary layers. Our particle image velocimetry measurements show that vorticity with both positive and negative sign is generated and that the smallest flow structures are 1 order of magnitude smaller than the boundary layer thickness. Additional local measurements using laser Doppler velocimetry yield turbulence intensities up to I=0.4 as in turbulent atmospheric boundary layers. From our observations, we conclude that the convective boundary layer becomes turbulent locally and temporarily although its Reynolds number Re ≈200 is considerably smaller than the value 420 underlying existing phenomenological theories. We think that, in turbulent Rayleigh-Bénard convection, the transition of the boundary layer towards turbulence depends on subtle details of the flow field and is therefore not universal.

  6. Super Ensemble-based Aviation Turbulence Guidance (SEATG) for Air Traffic Management (ATM)

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Hoon; Chan, William; Sridhar, Banavar; Sharman, Robert

    2014-05-01

    Super Ensemble (ensemble of ten turbulence metrics from time-lagged ensemble members of weather forecast data)-based Aviation Turbulence Guidance (SEATG) is developed using Weather Research and Forecasting (WRF) model and in-situ eddy dissipation rate (EDR) observations equipped on commercial aircraft over the contiguous United States. SEATG is a sequence of five procedures including weather modeling, calculating turbulence metrics, mapping EDR-scale, evaluating metrics, and producing final SEATG forecast. This uses similar methodology to the operational Graphic Turbulence Guidance (GTG) with three major improvements. First, SEATG use a higher resolution (3-km) WRF model to capture cloud-resolving scale phenomena. Second, SEATG computes turbulence metrics for multiple forecasts that are combined at the same valid time resulting in an time-lagged ensemble of multiple turbulence metrics. Third, SEATG provides both deterministic and probabilistic turbulence forecasts to take into account weather uncertainties and user demands. It is found that the SEATG forecasts match well with observed radar reflectivity along a surface front as well as convectively induced turbulence outside the clouds on 7-8 Sep 2012. And, overall performance skill of deterministic SEATG against the observed EDR data during this period is superior to any single turbulence metrics. Finally, probabilistic SEATG is used as an example application of turbulence forecast for air-traffic management. In this study, a simple Wind-Optimal Route (WOR) passing through the potential areas of probabilistic SEATG and Lateral Turbulence Avoidance Route (LTAR) taking into account the SEATG are calculated at z = 35000 ft (z = 12 km) from Los Angeles to John F. Kennedy international airports. As a result, WOR takes total of 239 minutes with 16 minutes of SEATG areas for 40% of moderate turbulence potential, while LTAR takes total of 252 minutes travel time that 5% of fuel would be additionally consumed to entirely

  7. Internal gravity wave-atmospheric wind interaction - A cause of clear air turbulence.

    NASA Technical Reports Server (NTRS)

    Bekofske, K.; Liu, V. C.

    1972-01-01

    The interaction between an internal gravity wave (IGW) and a vertical wind shear is discussed as a possible cause in the production of clear air turbulence in the free atmosphere. It is shown that under certain typical condition the interaction of an IGW with a background wind shear near a critical level provides a mechanism for depositing sufficient momentum in certain regions of the atmosphere to significantly increase the local mean wind shear and to lead to the production of turbulence.

  8. Hydrogen-air turbulent flame propagation in the presence of microdroplets

    NASA Astrophysics Data System (ADS)

    Medvedev, S. P.; Khomik, S. V.; Maximova, O. G.; Agafonov, G. L.; Mikhalkin, V. N.; Betev, A. S.

    2016-11-01

    A technique has been developed for evaluating turbulent combustion characteristics in the presence of microdroplets obtained by vapor condensation in the course of rapid expansion. Experiments have been conducted to visualize spark-initiated flame propagation through hydrogen-air mixtures at various turbulent intensities, water-vapor volume fractions, and microdroplet concentrations.The influence of microdroplet suspensions on iginition and flame propagation is investigated.

  9. Flight Tests of the DELICAT Airborne LIDAR System for Remote Clear Air Turbulence Detection

    NASA Astrophysics Data System (ADS)

    Vrancken, Patrick; Wirth, Martin; Ehret, Gerhard; Witschas, Benjamin; Veerman, Henk; Tump, Robert; Barny, Hervé; Rondeau, Philippe; Dolfi-Bouteyre, Agnès; Lombard, Laurent

    2016-06-01

    An important aeronautics application of lidar is the airborne remote detection of Clear Air Turbulence which cannot be performed with onboard radar. We report on a DLR-developed lidar system for the remote detection of such turbulent areas in the flight path of an aircraft. The lidar, consisting of a high-power UV laser transmitter and a direct detection system, was installed on a Dutch research aircraft. Flight tests executed in 2013 demonstrated the performance of the lidar system to detect local subtle variations in the molecular backscatter coefficient indicating the turbulence some 10 to 15 km ahead.

  10. Influence of Gas Turbulence on the Instability of an Air-Water Mixing Layer.

    PubMed

    Matas, Jean-Philippe; Marty, Sylvain; Dem, Mohamed Seydou; Cartellier, Alain

    2015-08-14

    We present the first evidence of the direct influence of gas turbulence on the shear instability of a planar air-water mixing layer. We show with two different experiments that increasing the level of velocity fluctuations in the gas phase continuously increases the frequency of the instability, up to a doubling of frequency for the largest turbulence intensity investigated. A modified spatiotemporal stability analysis taking turbulence into account via a simple Reynolds stress closure provides the right trend and magnitude for this effect.

  11. Modeling exposure close to air pollution sources in naturally ventilated residences: association of turbulent diffusion coefficient with air change rate.

    PubMed

    Cheng, Kai-Chung; Acevedo-Bolton, Viviana; Jiang, Ruo-Ting; Klepeis, Neil E; Ott, Wayne R; Fringer, Oliver B; Hildemann, Lynn M

    2011-05-01

    For modeling exposure close to an indoor air pollution source, an isotropic turbulent diffusion coefficient is used to represent the average spread of emissions. However, its magnitude indoors has been difficult to assess experimentally due to limitations in the number of monitors available. We used 30-37 real-time monitors to simultaneously measure CO at different angles and distances from a continuous indoor point source. For 11 experiments involving two houses, with natural ventilation conditions ranging from <0.2 to >5 air changes per h, an eddy diffusion model was used to estimate the turbulent diffusion coefficients, which ranged from 0.001 to 0.013 m² s⁻¹. The model reproduced observed concentrations with reasonable accuracy over radial distances of 0.25-5.0 m. The air change rate, as measured using a SF₆ tracer gas release, showed a significant positive linear correlation with the air mixing rate, defined as the turbulent diffusion coefficient divided by a squared length scale representing the room size. The ability to estimate the indoor turbulent diffusion coefficient using two readily measurable parameters (air change rate and room dimensions) is useful for accurately modeling exposures in close proximity to an indoor pollution source.

  12. Gene frequencies in the cat population of Buenos Aires, Argentina, and the possible origin of this population.

    PubMed

    Kajon, A; Centrón García, D; Ruiz-García, M

    1992-01-01

    The phenotypes of 295 stray cats seen in the capital area of Buenos Aires, Argentina, between March and December of 1989 were recorded. The corresponding mutant allele frequencies were as follows: O = 0.28, a = 0.83, Ta = 0.01; tb = 0.31; d = 0.45; I = 0.40; S = 0.28; W = 0.02. The allele frequencies calculated at the O locus were consistent with those expected for a randomly breeding population according to the formula for the Hardy-Weinberg equilibrium. The analysis of the genetic distances between Buenos Aires and several European cat populations revealed that the Spanish and, especially, those with a proven more ancestral genetic constitution, are the most closely related. When a similar analysis was carried out, including other Latin American cat populations, those of Spanish origin were found to show the highest degree of relatedness. These findings suggest that the Buenos Aires cat population was not genetically structured following the "two-stepping-stone" model and support the hypothesis that differential gene flows play a transcendental role in understanding the genetic composition of domestic cat populations.

  13. Development of Interfacial Structure in a Confined Air-Water Cap-Turbulent and Churn-Turbulent Flow

    SciTech Connect

    X. Sun; S. Kim; L. Cheng; M. Ishii; S.G. Beus

    2001-10-31

    The objective of the present work is to study and model the interfacial structure development of air-water two-phase flow in a confined test section. Experiments of a total of 9 flow conditions in a cap-turbulent and churn-turbulent flow regimes are carried out in a vertical air-water upward two-phase flow experimental loop with a test section of 20-cm in width and 1-cm in gap. The miniaturized four-sensor conductivity probes are used to measure local two-phase parameters at three different elevations for each flow condition. The bubbles captured by the probes are categorized into two groups in view of the two-group interfacial area transport equation, i.e., spherical/distorted bubbles as Group 1 and cap/churn-turbulent bubbles as Group 2. The acquired parameters are time-averaged local void fraction, interfacial velocity, bubble number frequency, interfacial area concentration, and bubble Sauter mean diameter for both groups of bubbles. Also, the line-averaged and area-averaged data are presented and discussed. The comparisons of these parameters at different elevations demonstrate the development of interfacial structure along the flow direction due to bubble interactions.

  14. Development of Interfacial Structure in a Confined Air-Water Cap-Turbulent and Churn-Turbulent Flow

    SciTech Connect

    Xiaodong Sun; Seungjin Kim; Ling Cheng; Mamoru Ishii; Beus, Stephen G.

    2002-07-01

    The objective of the present work is to study and model the interfacial structure development of air-water two-phase flow in a confined test section. Experiments of a total of 9 flow conditions in cap-turbulent and churn-turbulent flow regimes are carried out in a vertical air-water upward two-phase flow experimental loop with a test section of 200-mm in width and 10-mm in gap. Miniaturized four-sensor conductivity probes are used to measure local two-phase parameters at three different elevations for each flow condition. The bubbles captured by the probes are categorized into two groups in view of the two-group interfacial area transport equation, i.e., spherical/distorted bubbles as Group 1 and cap/churn-turbulent bubbles as Group 2. The acquired parameters are time-averaged local void fraction, interfacial velocity, bubble number frequency, interfacial area concentration, and bubble Sauter mean diameter for both groups of bubbles. Also, the line-averaged and area-averaged data are presented and discussed. The comparisons of these parameters at different elevations demonstrate the development of interfacial structure along the flow direction due to bubble interactions. (authors)

  15. Experimental study of the structure of isotropic turbulence with intermediate range of Reynolds number. [sea-air interaction

    NASA Technical Reports Server (NTRS)

    Ling, S. C.; Saad, A.

    1977-01-01

    The energetic isotropic turbulence generated by a waterfall of low head was found to be developed in part through the unstable two-phase flow of entrained air bubbles. The resulting turbulent field had a turbulent Reynolds number in excess of 20,000 and maintained a self-similar structure throughout the decay period studied. The present study may provide some insight into the structure of turbulence produced by breaking waves over the ocean.

  16. The Effect of Persistent Vortices on Boundary Layer Behavior in Turbulent Flow along a Kelvin-Stuart Cat's Eyes Wavy Wall

    NASA Astrophysics Data System (ADS)

    Mehmedagic, Amir

    The vortex persistence theory predicts that the addition of a sufficiently strong, stationary vortex near a wall will reduce the wall fluxes in turbulent flows. To test the theory flow visualization and hot-wire experiments in a water tunnel at moderate Reynolds number reveal that a persistent vortex will relaminarize the boundary layer along wavy even in the presence of freestream turbulence. This result is consistent with Dawson who found similar boundary layer behavior using a von Karman separatrix shaped wavy wall, and Balle, who's results showed laminar wall heat fluxes under stationary vortices using the von Karman wavy wall. Based on Dawson's flow visualization, and following Balle's analogy, the separatrix of a Kelvin-Stuart Cat's Eyes flow pattern was replaced with a solid wavy wall to stabilize the vortices shed by an array of half-delta vortex generators just upstream of the leading edge of the wavy wall. The correct angle of the array allows for persistent vortices to traverse along the grooves of the wavy wall, and displacing the array even slightly yields different turbulent fluxes. The present flow visualization and hot-wire anemometry results suggest that using the cat's eyes wavy wall gives better relaminarization properties than the von Karman shaped wavy wall, which can have many real world applications.

  17. Application of ERTS data to the detection of thin cirrus and clean air turbulence

    NASA Technical Reports Server (NTRS)

    Tsuchiya, K. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The feasibility of detecting a thin cirrus and clear air turbulence from ERTS-1 MSS data is explored. The result of analyses indicates that a thin cirrus not shown in a conventional meteorological satellite picture can be revealed in ERTS-1 MSS pictures. Is also found that the core of jet stream can be located with high accuracy from ERTS-1 pictures and the possible area of clear air turbulence can be predicted if the data of the quality of ERTS-1 data are available in real time.

  18. Turbulence and wave breaking effects on air-water gas exchange

    PubMed

    Boettcher; Fineberg; Lathrop

    2000-08-28

    We present an experimental characterization of the effects of turbulence and breaking gravity waves on air-water gas exchange in standing waves. We identify two regimes that govern aeration rates: turbulent transport when no wave breaking occurs and bubble dominated transport when wave breaking occurs. In both regimes, we correlate the qualitative changes in the aeration rate with corresponding changes in the wave dynamics. In the latter regime, the strongly enhanced aeration rate is correlated with measured acoustic emissions, indicating that bubble creation and dynamics dominate air-water exchange.

  19. Lagrangian analysis of premixed turbulent combustion in hydrogen-air flames

    NASA Astrophysics Data System (ADS)

    Darragh, Ryan; Poludnenko, Alexei; Hamlington, Peter

    2016-11-01

    Lagrangian analysis has long been a tool used to analyze non-reacting turbulent flows, and has recently gained attention in the reacting flow and combustion communities. The approach itself allows one to separate local molecular effects, such as those due to reactions or diffusion, from turbulent advective effects along fluid pathlines, or trajectories. Accurate calculation of these trajectories can, however, be rather difficult due to the chaotic nature of turbulent flows and the added complexity of reactions. In order to determine resolution requirements and verify the numerical algorithm, extensive tests are described in this talk for prescribed steady, unsteady, and chaotic flows, as well as for direct numerical simulations (DNS) of non-reacting homogeneous isotropic turbulence. The Lagrangian analysis is then applied to DNS of premixed hydrogen-air flames at two different turbulence intensities for both single- and multi-step chemical mechanisms. Non-monotonic temperature and fuel-mass fraction evolutions are found to exist along trajectories passing through the flame brush. Such non-monotonicity is shown to be due to molecular diffusion resulting from large spatial gradients created by turbulent advection. This work was supported by the Air Force Office of Scientific Research (AFOSR) under Award No. FA9550-14-1-0273, and the Department of Defense (DoD) High Performance Computing Modernization Program (HPCMP) under a Frontier project award.

  20. Ocean Winds and Turbulent Air-Sea Fluxes Inferred From Remote Sensing

    NASA Technical Reports Server (NTRS)

    Bourassa, Mark A.; Gille, Sarah T.; Jackson, Daren L.; Roberts, J. Brent; Wick, Gary A.

    2010-01-01

    Air-sea turbulent fluxes determine the exchange of momentum, heat, freshwater, and gas between the atmosphere and ocean. These exchange processes are critical to a broad range of research questions spanning length scales from meters to thousands of kilometers and time scales from hours to decades. Examples are discussed (section 2). The estimation of surface turbulent fluxes from satellite is challenging and fraught with considerable errors (section 3); however, recent developments in retrievals (section 3) will greatly reduce these errors. Goals for the future observing system are summarized in section 4. Surface fluxes are defined as the rate per unit area at which something (e.g., momentum, energy, moisture, or CO Z ) is transferred across the air/sea interface. Wind- and buoyancy-driven surface fluxes are called surface turbulent fluxes because the mixing and transport are due to turbulence. Examples of nonturbulent processes are radiative fluxes (e.g., solar radiation) and precipitation (Schmitt et al., 2010). Turbulent fluxes are strongly dependent on wind speed; therefore, observations of wind speed are critical for the calculation of all turbulent surface fluxes. Wind stress, the vertical transport of horizontal momentum, also depends on wind direction. Stress is very important for many ocean processes, including upper ocean currents (Dohan and Maximenko, 2010) and deep ocean currents (Lee et al., 2010). On short time scales, this horizontal transport is usually small compared to surface fluxes. For long-term processes, transport can be very important but again is usually small compared to surface fluxes.

  1. Simulation Analysis of Air Flow and Turbulence Statistics in a Rib Grit Roughened Duct

    PubMed Central

    Vogiatzis, I. I.; Denizopoulou, A. C.; Ntinas, G. K.; Fragos, V. P.

    2014-01-01

    The implementation of variable artificial roughness patterns on a surface is an effective technique to enhance the rate of heat transfer to fluid flow in the ducts of solar air heaters. Different geometries of roughness elements investigated have demonstrated the pivotal role that vortices and associated turbulence have on the heat transfer characteristics of solar air heater ducts by increasing the convective heat transfer coefficient. In this paper we investigate the two-dimensional, turbulent, unsteady flow around rectangular ribs of variable aspect ratios by directly solving the transient Navier-Stokes and continuity equations using the finite elements method. Flow characteristics and several aspects of turbulent flow are presented and discussed including velocity components and statistics of turbulence. The results reveal the impact that different rib lengths have on the computed mean quantities and turbulence statistics of the flow. The computed turbulence parameters show a clear tendency to diminish downstream with increasing rib length. Furthermore, the applied numerical method is capable of capturing small-scale flow structures resulting from the direct solution of Navier-Stokes and continuity equations. PMID:25057511

  2. Modeling variable density turbulence in the wake of an air-entraining transom stern

    NASA Astrophysics Data System (ADS)

    Hendrickson, Kelli; Yue, Dick

    2015-11-01

    This work presents a priori testing of closure models for the incompressible highly-variable density turbulent (IHVDT) flows in the near wake region of a transom stern. This three-dimensional flow is comprised of convergent corner waves that originate from the body and collide on the ship center plane forming the ``rooster tail'' that then widens to form the divergent wave train. These violent free-surface flows and breaking waves are characterized by significant turbulent mass flux (TMF) at Atwood number At = (ρ2 -ρ1) / (ρ2 +ρ1) ~ 1 for which there is little guidance in turbulence closure modeling for the momentum and scalar transport along the wake. To whit, this work utilizes high-resolution simulations of the near wake of a canonical three-dimensional transom stern using conservative Volume-of-Fluid (cVOF), implicit Large Eddy Simulation (iLES), and Boundary Data Immersion Method (BDIM) to capture the turbulence and large scale air entrainment. Analysis of the simulation results across and along the wake for the TMF budget and turbulent anisotropy provide the physical basis of the development of multiphase turbulence closure models. Performance of isotropic and anisotropic turbulent mass flux closure models will be presented. Sponsored by the Office of Naval Research.

  3. Characteristics of vertical and lateral tunnel turbulence measured in air in the Langley Transonic Dynamics Tunnel

    NASA Technical Reports Server (NTRS)

    Sleeper, Robert K.; Keller, Donald F.; Perry, Boyd, III; Sandford, Maynard C.

    1993-01-01

    Preliminary measurements of the vertical and lateral velocity components of tunnel turbulence were obtained in the Langley Transonic Dynamics Tunnel test section using a constant-temperature anemometer equipped with a hot-film X-probe. For these tests air was the test medium. Test conditions included tunnel velocities ranging from 100 to 500 fps at atmospheric pressure. Standard deviations of turbulence velocities were determined and power spectra were computed. Unconstrained optimization was employed to determine parameter values of a general spectral model of a form similar to that used to describe atmospheric turbulence. These parameters, and others (notably break frequency and integral scale length), were determined at each test condition and compared with those of Dryden and Von Karman atmospheric turbulence spectra. When the data were discovered to be aliased, the spectral model was modified to account for and 'eliminate' the aliasing.

  4. Surface Properties of Turbulent Liquid Jets in Still Air

    NASA Astrophysics Data System (ADS)

    Sallam, Khaled; Faeth, Gerard

    2001-11-01

    The mechanisms of creating drops from ligaments along the free surface of turbulent round and plane liquid jets in gases during turbulent primary breakup were investigated experimentally using pulsed holography. Jet exit conditions were limited to non-cavitating water and ethanol flows and long length-to-diameter ratio constant area injector passages at conditions where direct effects of liquid viscosity were small. Measurements involved drop/ligament diameter ratio, ligament angle, ligament slenderness ratio at the time of breakup, ligament breakup time and ligament tip velocity. The results show that the main mode of ligament breakup is Rayleigh breakup with the initial disturbance amplitude comparable to the ligament size and with drops forming at the tip of the ligament. A less common mode of drop formation involved ligament separation at its base due to velocity fluctuations. Ligament velocities were enhanced compared to the expectations of velocity fluctuations in turbulent pipe flows due to the smaller inertial resistance of the gas compared to the liquid.

  5. Numerical investigation of a turbulent hydraulic jump: Interface statistics and air entrainment

    NASA Astrophysics Data System (ADS)

    Mortazavi, Milad; Kim, Dokyun; Mani, Ali; Moin, Parviz

    2011-11-01

    The objective of this study is to develop an understanding of formation of bubbles due to turbulence/interface interactions and nonlinear surface wave phenomena. As a model problem a statistically stationary turbulent hydraulic jump has been considered. Turbulent hydraulic jump with an inflow Froude number of 2 and Reynolds number of 88000-based on inflow height-has been numerically simulated. Based on typical air- water systems, a density ratio of 831 has been selected for our calculations. A refined level-set method is employed to track the detailed dynamics of the interface evolution. Comparison of flow statistics with experimental results of Murzyn et al. (Int. J. Multiphase Flow, 2005) will be presented. The probability density function of principal curvatures of the air- water interface and curvature distribution patterns in the chaotic regions are investigated. The importance of liquid impact events in bubble generation will be discussed. Supported by the Office of Naval Research, with Dr. Pat Purtell, program manager.

  6. Indirect air-sea interactions simulated with a coupled turbulence-resolving model

    NASA Astrophysics Data System (ADS)

    Esau, Igor

    2014-05-01

    A turbulence-resolving parallelized atmospheric large-eddy simulation model (PALM) has been applied to study turbulent interactions between the humid atmospheric boundary layer (ABL) and the salt water oceanic mixed layer (OML). The most energetic three-dimensional turbulent eddies in the ABL-OML system (convective cells) were explicitly resolved in these simulations. This study considers a case of shear-free convection in the coupled ABL-OML system. The ABL-OML coupling scheme used the turbulent fluxes at the bottom of the ABL as upper boundary conditions for the OML and the sea surface temperature at the top of the OML as lower boundary conditions for the ABL. The analysis of the numerical experiment confirms that the ABL-OML interactions involve both the traditional direct coupling mechanism and much less studied indirect coupling mechanism (Garrett Dyn Atmos Ocean 23:19-34, 1996). The direct coupling refers to a common flux-gradient representation of the air-sea exchange, which is controlled by the temperature difference across the air-water interface. The indirect coupling refers to thermal instability of the Rayleigh-Benard convection, which is controlled by the temperature difference across the entire mixed layer through formation of the large convective eddies or cells. The indirect coupling mechanism in these simulations explained up to 45 % of the ABL-OML co-variability on the turbulent scales. Despite relatively small amplitude of the sea surface temperature fluctuations, persistence of the OML cells organizes the ABL convective cells. Water downdrafts in the OML cells tend to be collocated with air updrafts in the ABL cells. The study concludes that the convective structures in the ABL and the OML are co-organized. The OML convection controls the air-sea turbulent exchange in the quasi-equilibrium convective ABL-OML system.

  7. Development of CO2 laser Doppler instrumentation for detection of clear air turbulence, volume 2: Appendices

    NASA Technical Reports Server (NTRS)

    Harris, C. E.; Jelalian, A. V.

    1979-01-01

    Analyses of the mounting and mount support systems of the clear air turbulence transmitters verify that satisfactory shock and vibration isolation are attained. The mount support structure conforms to flight crash safety requirements with high margins of safety. Restraint cables reinforce the mounts in the critical loaded forward direction limiting maximum forward system deflection to 1 1/4 inches.

  8. Effects of radiation on NO kinetics in turbulent hydrogen/air diffusion flames

    SciTech Connect

    Sivathanu, Y.R.; Gore, J.P.; Laurendeau, N.M.

    1997-07-01

    The authors describe a coupled radiation and NO kinetics calculation of turbulent hydrogen/air diffusion flame properties. Transport equations for mass, momentum, mixture fraction, enthalpy (sensible + chemical) including gas band radiation, and NO mass fraction are solved. NO kinetics is described by a one step thermal production mechanism. The local temperature is obtained by solving the enthalpy equation taking radiation loss from H{sub 2}O into consideration. Radiation/turbulence and chemical kinetics/turbulence interactions are treated using a clipped Gaussian probability density function (PDF) for the mixture fraction, and a delta PDF for the enthalpy. The source terms in the enthalpy and mass fraction of NO equations are treated using assumed PDF integration over the mixture fraction space. The results of the simulation are compared with existing measurements of the Emission Indices of NO (EINO) in turbulent H{sub 2}/air diffusion flames. The major conclusion of the paper is that coupled turbulence/radiation interactions should be taken into account while computing the EINO.

  9. Direct numerical simulation of turbulent non-premixed methane-air flames

    SciTech Connect

    Chen, J.H.; Card, J.M.; Day, M.; Mahalingam, S.

    1995-07-01

    Turbulent non-premixed stoichiometric methane-air flames have been studied using the direct numerical simulation approach. A global one- step mechanism is used to describe the chemical kinetics, and molecular transport is modeled with constant Lewis numbers for individual species. The effect of turbulence on the internal flame structure and extinction characteristics of methane-air flames is evaluated. The flame is wrinkled and in some regions extinguished by the turbulence, while the turbulence is weakened in the vicinity of the flame due to a combination of dilatation and a 25:1 increase in kinematic viscosity across the flame. Reignition followed by partially-premixed burning is observed in the present results. Local curvature effects are found to be important in determining the local stoichiometry of the flame, and hence, the location of the peak reaction rate relative to the stoichiometric surface. The results presented in this study demonstrate the feasibility of incorporating global-step kinetics for the oxidation of methane into direct numerical simulations of homogeneous turbulence to study the flame structure.

  10. Direct numerical simulations of turbulent non-premixed methane-air flames modeled with reduced kinetics

    NASA Technical Reports Server (NTRS)

    Card, J. M.; Chen, J. H.; Day, M.; Mahalingam, S.

    1994-01-01

    Turbulent non-premixed stoichiometric methane-air flames modeled with reduced kinetics have been studied using the direct numerical simulation approach. The simulations include realistic chemical kinetics, and the molecular transport is modeled with constant Lewis numbers for individual species. The effect of turbulence on the internal flame structure and extinction characteristics of methane-air flames is evaluated. Consistent with earlier DNS with simple one-step chemistry, the flame is wrinkled and in some regions extinguished by the turbulence, while the turbulence is weakened in the vicinity of the flame due to a combination of dilatation and an increase in kinematic viscosity. Unlike previous results, reignition is observed in the present simulations. Lewis number effects are important in determining the local stoichiometry of the flame. The results presented in this work are preliminary but demonstrate the feasibility of incorporating reduced kinetics for the oxidation of methane with direct numerical simulations of homogeneous turbulence to evaluate the limitations of various levels of reduction in the kinetics and to address the formation of thermal and prompt NO(x).

  11. Twisted photon entanglement through turbulent air across Vienna

    PubMed Central

    Krenn, Mario; Handsteiner, Johannes; Fink, Matthias; Fickler, Robert; Zeilinger, Anton

    2015-01-01

    Photons with a twisted phase front can carry a discrete, in principle, unbounded amount of orbital angular momentum (OAM). The large state space allows for complex types of entanglement, interesting both for quantum communication and for fundamental tests of quantum theory. However, the distribution of such entangled states over large distances was thought to be infeasible due to influence of atmospheric turbulence, indicating a serious limitation on their usefulness. Here we show that it is possible to distribute quantum entanglement encoded in OAM over a turbulent intracity link of 3 km. We confirm quantum entanglement of the first two higher-order levels (with OAM=± 1ℏ and ± 2ℏ). They correspond to four additional quantum channels orthogonal to all that have been used in long-distance quantum experiments so far. Therefore, a promising application would be quantum communication with a large alphabet. We also demonstrate that our link allows access to up to 11 quantum channels of OAM. The restrictive factors toward higher numbers are technical limitations that can be circumvented with readily available technologies. PMID:26578763

  12. Turbulent Combustion in Aluminum-air Clouds for Different Scale Explosion Fields

    NASA Astrophysics Data System (ADS)

    Kuhl, Allen; Balakrishnan, Kaushik; Bell, John; Beckner, Vincent

    2015-06-01

    We have studied turbulent combustion effects in explosions, and proposed heterogeneous continuum models for the turbulent combustion fields. Also we have proposed an induction-time model for the ignition of Al particle clouds, based on Arrhenius fits to the shock tube data of Boiko. Here we explore scaling issues associated with Al particle combustion in such explosions. This is a non-premixed combustion system; the global burning rate is controlled by rate of turbulent mixing of fuel (Al particles) with air. For similitude reasons, the turbulent mixing rates should scale with the explosion length and time scales. However, the induction time for ignition of Al particles depends on an Arrhenius function, which is independent of such scales. To study this, we have performed numerical simulations of turbulent combustion in unconfined Al-SDF (shock-dispersed-fuel) explosion fields at different scales. Three different charge masses were assumed: 1-g, 1-kg and 1-T Al-powder charges. We found that there are two combustion regimes: an ignition regime--where the burning rate decays a power law function of time, and a turbulent combustion regime--where the burning rate decays exponentially with time.

  13. Investigation of Ignition and Combustion Processes of Diesel Engines Operating with Turbulence and Air-storage Chambers

    NASA Technical Reports Server (NTRS)

    Petersen, Hans

    1938-01-01

    The flame photographs obtained with combustion-chamber models of engines operating respectively, with turbulence chamber and air-storage chambers or cells, provide an insight into the air and fuel movements that take place before and during combustion in the combustion chamber. The relation between air velocity, start of injection, and time of combustion was determined for the combustion process employing a turbulence chamber.

  14. Viral diagnostic criteria for Feline immunodeficiency virus and Feline leukemia virus infections in domestic cats from Buenos Aires, Argentina.

    PubMed

    Galdo Novo, Sabrina; Bucafusco, Danilo; Diaz, Leandro M; Bratanich, Ana Cristina

    A cross-sectional study was carried out on cats attending the Small Animal Hospital at the Faculty of Veterinary Sciences of the University of Buenos Aires to assess the prevalence and associated risk factors of Feline immunodeficiency virus (FIV) and Feline leukemia virus (FeLV) in the city of Buenos Aires, Argentina. Blood samples from 255 cats with symptoms compatible with FIV or FeLV infection, collected between 2009 and 2013 were analyzed by serology (immunochromatography, IA) and by hemi-nested PCR (n-PCR). The IA and n-PCR assays showed similar percentages of positivity for FIV while the n-PCR test was more sensitive for FeLV. Differences between the diagnostic tests and their choice according to the age of the animal are discussed. The clinical histories of ninety of the 255 cats showed blood profiles similar to others previously reported and revealed a higher risk of infection in male adult cats with outdoor access.

  15. Flight tests of a simple airborne device for predicting clear air turbulence encounters

    NASA Technical Reports Server (NTRS)

    Kurkowski, R. L.; Duller, C. E., III; Kuhn, P. M.

    1978-01-01

    An airborne clear-air turbulence detector is being flight-tested on board NASA's C-141 and Learjet aircraft. The device is an infrared (IR) sensor in the water vapor band and is designed to detect changes in vapor concentrations associated with turbulence in shear conditions. Warnings of about 5 min have been demonstrated at flight altitudes from 9.1 to 13.7 km (30,000 to 45,000 ft). Encounter predictions were obtained 80% of the time, and false alarms were given about 6% of the time. Several simple algorithms were studied for use as signal output analyzers and for alert triggering.

  16. NASA technical advances in aircraft occupant safety. [clear air turbulence detectors, fire resistant materials, and crashworthiness

    NASA Technical Reports Server (NTRS)

    Enders, J. H.

    1978-01-01

    NASA's aviation safety technology program examines specific safety problems associated with atmospheric hazards, crash-fire survival, control of aircraft on runways, human factors, terminal area operations hazards, and accident factors simulation. While aircraft occupants are ultimately affected by any of these hazards, their well-being is immediately impacted by three specific events: unexpected turbulence encounters, fire and its effects, and crash impact. NASA research in the application of laser technology to the problem of clear air turbulence detection, the development of fire resistant materials for aircraft construction, and to the improvement of seats and restraint systems to reduce crash injuries are reviewed.

  17. Turbulence

    NASA Astrophysics Data System (ADS)

    Frisch, Uriel

    1996-01-01

    Written five centuries after the first studies of Leonardo da Vinci and half a century after A.N. Kolmogorov's first attempt to predict the properties of flow, this textbook presents a modern account of turbulence, one of the greatest challenges in physics. "Fully developed turbulence" is ubiquitous in both cosmic and natural environments, in engineering applications and in everyday life. Elementary presentations of dynamical systems ideas, probabilistic methods (including the theory of large deviations) and fractal geometry make this a self-contained textbook. This is the first book on turbulence to use modern ideas from chaos and symmetry breaking. The book will appeal to first-year graduate students in mathematics, physics, astrophysics, geosciences and engineering, as well as professional scientists and engineers.

  18. Analysis of turbulent free jet hydrogen-air diffusion flames with finite chemical reaction rates

    NASA Technical Reports Server (NTRS)

    Sislian, J. P.

    1978-01-01

    The nonequilibrium flow field resulting from the turbulent mixing and combustion of a supersonic axisymmetric hydrogen jet in a supersonic parallel coflowing air stream is analyzed. Effective turbulent transport properties are determined using the (K-epsilon) model. The finite-rate chemistry model considers eight reactions between six chemical species, H, O, H2O, OH, O2, and H2. The governing set of nonlinear partial differential equations is solved by an implicit finite-difference procedure. Radial distributions are obtained at two downstream locations of variables such as turbulent kinetic energy, turbulent dissipation rate, turbulent scale length, and viscosity. The results show that these variables attain peak values at the axis of symmetry. Computed distributions of velocity, temperature, and mass fraction are also given. A direct analytical approach to account for the effect of species concentration fluctuations on the mean production rate of species (the phenomenon of unmixedness) is also presented. However, the use of the method does not seem justified in view of the excessive computer time required to solve the resulting system of equations.

  19. Interaction of Thermodiffusive Instabilities and Turbulence in Lean Hydrogen/Air Mixtures using Tabulated Chemistry

    NASA Astrophysics Data System (ADS)

    Schlup, Jason; Blanquart, Guillaume

    2015-11-01

    The combustion of lean hydrogen mixtures is prone to thermodiffusive instabilities due to the strongly non-unity fuel Lewis number. Simulations of the combustion process can aid in designing new burners to reduce operating risks associated with thermodiffusive instabilities; however, direct numerical simulations of large scale burners with detailed chemistry mechanisms are prohibitively expensive. The significant simulation time requires that computational costs decrease by using reduced order chemistry and turbulence modeling. In this work, a chemistry table, created with one-dimensional flames, is used to reduce the simulation cost. Direct numerical simulations of turbulent combustion with lean hydrogen/air mixtures are performed. Both statistically planar and spherically expanding flames are considered, and the turbulence level varies from laminar to fully turbulent flow conditions. The chosen equivalence ratio displays thermodiffusive instabilities in the wrinkled flame front. The influence of turbulence intensity on the flame instabilities are explored, and the results are compared to previous studies to determine the adequacy of the tabulated chemistry method for this set of simulation parameters.

  20. Surface properties of turbulent premixed propane/air flames at various Lewis numbers

    SciTech Connect

    Lee, T.W.; North, G.L.; Santavicca, D.A. )

    1993-06-01

    Surface properties of turbulent premixed flames including the wrinkled flame perimeter, fraction of the flame pocket perimeter, flame curvature, and orientation distributions have been measured for propane-air flames at Lewis numbers ranging from 0.98 to 1.86 and u[prime]/S[sub L] = 1.42-5.71. The wrinkled flame perimeter is found to be greater for the thermodiffusively unstable Lewis number (Le < 1) by up to 30% in comparison to the most stable condition (Le = 1.86) tested, while the fraction of the flame pocket perimeter shows a similar tendency to be greater for Le < 1. The flame curvature probability density functions are nearly symmetric with respect to the zero mean at all Lewis numbers throughout the range of u[prime]/S[sub L] tested, and show a much stronger dependence on the turbulence condition than on the Lewis number. Similarly, the flame orientation distributions show a trend from anisotropy toward a more uniform distribution with increasing u[prime]/S[sub L] at a similar rate for all Lewis numbers. Thus, for turbulent premixed propane/air flames for a practical range of Lewis number from 0.98 to 1.86, the effect of Lewis number is primarily to affect the flame structures and thereby flame surface areas and flame pocket areas, while the flame curvature and orientation statistics are essentially determined by the turbulence properties.

  1. Turbulent Fluxes and Pollutant Mixing during Wintertime Air Pollution Episodes in Complex Terrain.

    PubMed

    Holmes, Heather A; Sriramasamudram, Jai K; Pardyjak, Eric R; Whiteman, C David

    2015-11-17

    Cold air pools (CAPs) are stagnant stable air masses that form in valleys and basins in the winter. Low wintertime insolation limits convective mixing, such that pollutant concentrations can build up within the CAP when pollutant sources are present. In the western United States, wintertime CAPs often persist for days or weeks. Atmospheric models do not adequately capture the strength and evolution of CAPs. This is in part due to the limited availability of data quantifying the local turbulence during the formation, maintenance, and destruction of persistent CAPs. This paper presents observational data to quantify the turbulent mixing during two CAP episodes in Utah's Salt Lake Valley during February of 2004. Particulate matter (PM) concentration data and turbulence measurements for CAP and non-CAP time periods indicate that two distinct types of mixing scenarios occur depending on whether the CAP is dry or cloudy. Where cloudy, CAPs have enhanced vertical mixing due to top-down convection from the cloud layer. A comparison between the heat and momentum fluxes during 5 days of a dry CAP episode in February to those of an equivalent 5 day time period in March with no CAP indicates that the average turbulent kinetic energy during the CAP was suppressed by approximately 80%.

  2. Spectra of concentration of air pollution for turbulent convection

    SciTech Connect

    Patel, S.R.

    1996-12-31

    Very recently the study of formation and destruction of photochemical smog is increasing at both small and large scale. Also the transport of chemical species through the Planetary Boundary Layer (PBL) of the atmosphere is a key of the global change problem and will have to be parameterized more reliably than in the past. Further, in the air pollution modeling, the usual practice of neglecting the concentration correlation in the atmospheric photochemical reaction has recently been recognized as a source of serious error. So, it is important to study the various aspects of the concentration fluctuations (of air pollution) with chemical reaction. A model of the spectrum of concentration of air pollution with chemical reaction has been developed using the models of Hill and Hill and Clifford. The results obtained are applicable for arbitrary Schmidt number. Further, for the case of pure mixing (without chemical reaction) and the concentration replaced by temperature, the form of the spectra obtained here reduces to the form obtained by Hill and Clifford. This study also shows that, in the case of pure mixing, the concentration decays in a natural manner, but if the concentration selected is that of the chemical reactant, then the effect is that the dispersion of the concentration is much more rapid.

  3. Numerical simulation in finite elements of turbulent flows of viscous incompressible fluids in air intakes

    NASA Astrophysics Data System (ADS)

    Begue, C.; Periaux, J.; Perrier, P.; Pouletty, C.

    1985-11-01

    A self-adaptive finite-element method, coupled to a homogenization model of turbulence, is presented for the numerical simulation of unsteady turbulent flow of viscous fluids in air intakes. The nonlinear subproblem due to the convection is solved by an iterative algorithm, and the linear Stokes subproblem due to the diffusion is solved by a Hood-Taylor type iterative algorithm. An efficient and precise minielement approximation is used, and the adaptive mesh procedure is automatic in the calculation, using the physical criteria of rotation and divergence to determine the submeshing zones. The numerical method is demonstrated for the example of three-dimensional laminar flow around and in air intake at a Reynolds number of 200.

  4. Hot-wire anemometry for turbulence measurements in helium-air mixtures

    NASA Technical Reports Server (NTRS)

    Libby, P. A.; Larue, J. C.

    1979-01-01

    The use of extended hot-wire anemometry involving an interfering probe is shown to permit measurements of variable density turbulence such as arises in the mixing of helium and air. The methods of calibration and data reduction leading to time series in one or more velocity components, in the mass fraction of helium, and in the mixture density are described. Typical results in various flows to which the technique has been applied are discussed.

  5. Alternating-Current Equipment for the Measurement of Fluctuations of Air Speed in Turbulent Flow

    NASA Technical Reports Server (NTRS)

    Mock, W C , Jr

    1937-01-01

    Recent electrical and mechanical improvements have been made in the equipment developed at the National Bureau of Standards for measurement of fluctuations of air speed in turbulent flow. Data useful in the design of similar equipment are presented. The design of rectified alternating-current power supplies for such apparatus is treated briefly, and the effect of the power supplies on the performance of the equipment is discussed.

  6. Shear turbulence, Langmuir circulation and scalar transfer at an air-water interface

    NASA Astrophysics Data System (ADS)

    Hafsi, Amine; Tejada-Martinez, Andres; Veron, Fabrice

    2016-11-01

    DNS of an initially quiescent coupled air-water interface driven by an air-flow with free stream speed of 5 m/s generates gravity-capillary waves and small-scale (centimeter-scale) Langmuir circulation (LC) beneath the interface. In addition to LC, the waterside turbulence is characterized by shear turbulence with structures similar to classical "wall streaks" in wall-bounded flow. These streaks, denoted here as "shear streaks", consist of downwind-elongated vortices alternating in sign in the crosswind direction. The presence of interfacial waves causes interaction between these vortices giving rise to bigger vortices, namely LC. LES with momentum equation augmented with the Craik-Leibovich (C-L) vortex force is used to understand the roles of the shear streaks (i.e. the shear turbulence) and the LC in determining scalar flux from the airside to the waterside and vertical scalar transport beneath. The C-L force consists of the cross product between the Stokes drift velocity (induced by the interface waves) and the flow vorticity. It is observed that Stokes drift shear intensifies the shear streaks (with respect to flow without wave effects) leading to enhanced scalar flux at the air-water interface. LC leads to increased vertical scalar transport at depths below the interface.

  7. Improved Apparatus for the Measurement of Fluctuations of Air Speed in Turbulent Flow

    NASA Technical Reports Server (NTRS)

    Mock, W C , Jr; Dryden, H L

    1934-01-01

    This report describes recent improvements in the design of the equipment associated with the hot-wire anemometer for the measurement of fluctuating air speeds in turbulent air flow, and presents the results of some experimental investigations dealing with the response of the hot wire to speed fluctuations of various frequencies. Attempts at measuring the frequency of the fluctuations encountered in the Bureau of Standards' 54-inch wind tunnel are also reported. In addition, the difficulties encountered in the use of such apparatus and the precautions found helpful in avoiding them are discussed.

  8. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

    DOE PAGES

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; ...

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore » the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  9. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

    SciTech Connect

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall on the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.

  10. Flame front surface characteristics in turbulent premixed propane/air combustion

    SciTech Connect

    Guelder, O.L.; Smallwood, G.J.; Wong, R.; Snelling, D.R.; Smith, R.; Deschamps, B.M.; Sautet, J.C.

    2000-03-01

    The characteristics of the flame front surfaces in turbulent premixed propane/air flames were investigated. Flame front images were obtained using laser-induced fluorescence (LIF) of OH and Mie scattering on two Bunsen-type burners of 11.2-mm and 22.4-mm diameters. Nondimensional turbulence intensity, u{prime}/S{sub L}, was varied from 0.9 to 15, and the Reynolds number, based on the integral length scale, varied from 40 to 467. Approximately 100 images were recorded for each experimental condition. Fractal parameters (fractal dimension, inner and outer cutoffs) and corresponding standard deviations were determined by analysis of the flame front images using the caliper technique. The fractal dimensions derived from OH and Mie scattering images are almost identical. However, inner and outer cutoffs from OH images are consistently higher than those obtained from Mie scattering. The self-similar region of the flame front wrinkling is about a decade for all flames studied. In the nondimensional turbulence intensity range from 1 to 15, it was found that the mean fractal dimension is about 2.2 and it does not show any dependence on turbulence intensity. This contradicts the findings of the previous studies that showed that the fractal dimension asymptotically reaches to 2.35--2.37 when the nondimensional turbulence intensity u{prime}/S{sub L} exceeds 3. It is shown that the reason for this discrepancy is the image analysis method used in the previous studies. Examples are given to show the inadequacy of the circle method used in previous studies for extraction of fractal parameters from flame front images. The fractal parameters obtained so far, in this and previous studies, are not capable of correctly predicting the turbulent burning velocity using the available fractal area closure model.

  11. Control of turbulent boundary layer through air blowing due to external-flow resources

    NASA Astrophysics Data System (ADS)

    Kornilov, V. I.; Boiko, A. V.; Kavun, I. N.

    2015-07-01

    The possibility to control turbulent incompressible boundary layer using air blowing through a finely perforated wall presenting part of the streamlined flat-plate surface was examined. The control was exercised via an action on the state and characteristics of the near-wall flow exerted by controlled (through variation of external-pressure-flow velocity) blowing of air through an air intake installed on the idle side of the plate. A stable reduction of the local values of skin friction coefficient along the model, reaching 50 % at the end of the perforated area, has been demonstrated. The obtained experimental and calculated data are indicative of a possibility to model the process of turbulentboundary-layer control by air blowing due to external-flow resources.

  12. Analysis of turbulent free-jet hydrogen-air diffusion flames with finite chemical reaction rates

    NASA Technical Reports Server (NTRS)

    Sislian, J. P.; Glass, I. I.; Evans, J. S.

    1979-01-01

    A numerical analysis is presented of the nonequilibrium flow field resulting from the turbulent mixing and combustion of an axisymmetric hydrogen jet in a supersonic parallel ambient air stream. The effective turbulent transport properties are determined by means of a two-equation model of turbulence. The finite-rate chemistry model considers eight elementary reactions among six chemical species: H, O, H2O, OH, O2 and H2. The governing set of nonlinear partial differential equations was solved by using an implicit finite-difference procedure. Radial distributions were obtained at two downstream locations for some important variables affecting the flow development, such as the turbulent kinetic energy and its dissipation rate. The results show that these variables attain their peak values on the axis of symmetry. The computed distribution of velocity, temperature, and mass fractions of the chemical species gives a complete description of the flow field. The numerical predictions were compared with two sets of experimental data. Good qualitative agreement was obtained.

  13. Direct Numerical Simulations of Autoignition in Stratified Dimethyl-ether (DME)/Air Turbulent Mixtures

    SciTech Connect

    Bansal, Gaurav; Mascarenhas, Ajith; Chen, Jacqueline H.

    2014-10-01

    In our paper, two- and three-dimensional direct numerical simulations (DNS) of autoignition phenomena in stratified dimethyl-ether (DME)/air turbulent mixtures are performed. A reduced DME oxidation mechanism, which was obtained using rigorous mathematical reduction and stiffness removal procedure from a detailed DME mechanism with 55 species, is used in the present DNS. The reduced DME mechanism consists of 30 chemical species. This study investigates the fundamental aspects of turbulence-mixing-autoignition interaction occurring in homogeneous charge compression ignition (HCCI) engine environments. A homogeneous isotropic turbulence spectrum is used to initialize the velocity field in the domain. Moreover, the computational configuration corresponds to a constant volume combustion vessel with inert mass source terms added to the governing equations to mimic the pressure rise due to piston motion, as present in practical engines. DME autoignition is found to be a complex three-staged process; each stage corresponds to a distinct chemical kinetic pathway. The distinct role of turbulence and reaction in generating scalar gradients and hence promoting molecular transport processes are investigated. Then, by applying numerical diagnostic techniques, the different heat release modes present in the igniting mixture are identified. In particular, the contribution of homogeneous autoignition, spontaneous ignition front propagation, and premixed deflagration towards the total heat release are quantified.

  14. Direct Numerical Simulations of Autoignition in Stratified Dimethyl-ether (DME)/Air Turbulent Mixtures

    DOE PAGES

    Bansal, Gaurav; Mascarenhas, Ajith; Chen, Jacqueline H.

    2014-10-01

    In our paper, two- and three-dimensional direct numerical simulations (DNS) of autoignition phenomena in stratified dimethyl-ether (DME)/air turbulent mixtures are performed. A reduced DME oxidation mechanism, which was obtained using rigorous mathematical reduction and stiffness removal procedure from a detailed DME mechanism with 55 species, is used in the present DNS. The reduced DME mechanism consists of 30 chemical species. This study investigates the fundamental aspects of turbulence-mixing-autoignition interaction occurring in homogeneous charge compression ignition (HCCI) engine environments. A homogeneous isotropic turbulence spectrum is used to initialize the velocity field in the domain. Moreover, the computational configuration corresponds to amore » constant volume combustion vessel with inert mass source terms added to the governing equations to mimic the pressure rise due to piston motion, as present in practical engines. DME autoignition is found to be a complex three-staged process; each stage corresponds to a distinct chemical kinetic pathway. The distinct role of turbulence and reaction in generating scalar gradients and hence promoting molecular transport processes are investigated. Then, by applying numerical diagnostic techniques, the different heat release modes present in the igniting mixture are identified. In particular, the contribution of homogeneous autoignition, spontaneous ignition front propagation, and premixed deflagration towards the total heat release are quantified.« less

  15. Turbulent combustion in aluminum-air clouds for different scale explosion fields

    NASA Astrophysics Data System (ADS)

    Kuhl, Allen L.; Balakrishnan, Kaushik; Bell, John B.; Beckner, Vincent E.

    2017-01-01

    This paper explores "scaling issues" associated with Al particle combustion in explosions. The basic idea is the following: in this non-premixed combustion system, the global burning rate is controlled by rate of turbulent mixing of fuel (Al particles) with air. From similarity considerations, the turbulent mixing rates should scale with the explosion length and time scales. However, the induction time for ignition of Al particles depends on an Arrhenius function, which is independent of the explosion length and time. To study this, we have performed numerical simulations of turbulent combustion in unconfined Al-SDF (shock-dispersed-fuel) explosion fields at different scales. Three different charge masses were assumed: 1-g, 1-kg and 1-T Al-powder charges. We found that there are two combustion regimes: an ignition regime—where the burning rate decays as a power-law function of time, and a turbulent combustion regime—where the burning rate decays exponentially with time. This exponential dependence is typical of first order reactions and the more general concept of Life Functions that control the dynamics of evolutionary systems. Details of the combustion model are described. Results, including mean and rms profiles in combustion cloud and fuel consumption histories, are presented.

  16. Lidar sounding of the optical parameter of atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Gurvich, A. S.; Fortus, M. I.

    2016-03-01

    The operation of a lidar intended for clear air turbulence (CAT) positioning on the basis of the backscatter enhancement (BSE) effect is analyzed using a turbulence model with a power-law spectrum. Systematic distortions occurring due to a need to regularize the lidar positioning problem solution are estimated. It is shown that the effect of molecular viscosity of air on the positioning result can be neglected if the wave parameter, which characterizes the diffraction manifestation, is higher than 3. This corresponds to sounding ranges of more than 1 km for optical or UV lidars. The analysis results show that the BSE lidar positioning accuracy weakly depends on the exponent in the turbulence spectrum in regions of severe turbulence. The results can justify a physical experiment for the design of an aircraft system for the lidar detection of CAT regions ahead of the flight course.

  17. Clear air turbulence as a response to meso- and synoptic-scale dynamic processes

    NASA Technical Reports Server (NTRS)

    Keller, John L.

    1990-01-01

    The paper presents both the Roach equation for the rate of energy dissipation due to clear air turbulence and Richardson number tendencies in isentropic coordinates and examines the implications of these formulations to determine whether there is a dynamic interdependence between Ri and the nonturbulent deformation processes. The equation representing the ln(Ri) tendency is applied diagnostically to grids from an isentropic analysis of archived soundings. The evolution of the Richardson number fields over 12-hour time periods is examined using a mechanistic model. It is suggested that the application of the Roach equation for the turbulent dissipation rate should have a more restricted use. Analyses of the meso-alpha scale Richardson number and of the Richardson number tendency fields reveal a phase relationship consistent with the theoretical predictions.

  18. Air-sea fluxes and surface layer turbulence around a sea surface temperature front

    NASA Technical Reports Server (NTRS)

    Friehe, C. A.; Shaw, W. J.; Davidson, K. L.; Rogers, D. P.; Large, W. G.; Stage, S. A.; Crescenti, G. H.; Khalsa, S. J. S.; Greenhut, G. K.; Li, F.

    1991-01-01

    The observed effects of sharp changes in sea surface temperature (SST) on the air-sea fluxes, surface roughness, and the turbulence structure in the surface layer and the marine atmospheric boundary layer are discussed. In situ flux and turbulence observations were carried out from three aircraft and two ships within the FASINEX framework. Three other aircraft used remote sensors to measure waves, microwave backscatter, and lidar signatures of cloud tops. Descriptions of the techniques, intercomparison of aircraft and ship flux data, and use of different methods for analyzing the fluxes from the aircraft data are described. Changing synoptic weather on three successive days yielded cases of wind direction both approximately parallel and perpendicular to a surface temperature front. For the wind perpendicular to the front, wind over both cold-to-warm and warm-to-cold surface temperatures occurred. Model results consistent with the observations suggest that an internal boundary layer forms at the SST.

  19. Turbulent heat and mass transfers across a thermally stratified air-water interface

    NASA Technical Reports Server (NTRS)

    Papadimitrakis, Y. A.; Hsu, Y.-H. L.; Wu, J.

    1986-01-01

    Rates of heat and mass transfer across an air-water interface were measured in a wind-wave research facility, under various wind and thermal stability conditions (unless otherwise noted, mass refers to water vapor). Heat fluxes were obtained from both the eddy correlation and the profile method, under unstable, neutral, and stable conditions. Mass fluxes were obtained only under unstable stratification from the profile and global method. Under unstable conditions the turbulent Prandtl and Schmidt numbers remain fairly constant and equal to 0.74, whereas the rate of mass transfer varies linearly with bulk Richardson number. Under stable conditions the turbulent Prandtl number rises steadily to a value of 1.4 for a bulk Richardson number of about 0.016. Results of heat and mass transfer, expressed in the form of bulk aerodynamic coefficients with friction velocity as a parameter, are also compared with field data.

  20. Monte-Carlo computation of turbulent premixed methane/air ignition

    NASA Astrophysics Data System (ADS)

    Carmen, Christina Lieselotte

    The present work describes the results obtained by a time dependent numerical technique that simulates the early flame development of a spark-ignited premixed, lean, gaseous methane/air mixture with the unsteady spherical flame propagating in homogeneous and isotropic turbulence. The algorithm described is based upon a sub-model developed by an international automobile research and manufacturing corporation in order to analyze turbulence conditions within internal combustion engines. Several developments and modifications to the original algorithm have been implemented including a revised chemical reaction scheme and the evaluation and calculation of various turbulent flame properties. Solution of the complete set of Navier-Stokes governing equations for a turbulent reactive flow is avoided by reducing the equations to a single transport equation. The transport equation is derived from the Navier-Stokes equations for a joint probability density function, thus requiring no closure assumptions for the Reynolds stresses. A Monte-Carlo method is also utilized to simulate phenomena represented by the probability density function transport equation by use of the method of fractional steps. Gaussian distributions of fluctuating velocity and fuel concentration are prescribed. Attention is focused on the evaluation of the three primary parameters that influence the initial flame kernel growth-the ignition system characteristics, the mixture composition, and the nature of the flow field. Efforts are concentrated on the effects of moderate to intense turbulence on flames within the distributed reaction zone. Results are presented for lean conditions with the fuel equivalence ratio varying from 0.6 to 0.9. The present computational results, including flame regime analysis and the calculation of various flame speeds, provide excellent agreement with results obtained by other experimental and numerical researchers.

  1. MU radar and lidar observations of clear-air turbulence and mammatus underneath cirrus

    NASA Astrophysics Data System (ADS)

    Luce, H.; Nakamura, T.; Yamamoto, M.; Fukao, S.

    2009-04-01

    Mammatus are smooth hanging protuberances on the undersurface of a cloud (Glossary of Meteorology). Their mechanisms for formation and their role in the atmosphere are still not well-known. We obtained Rayleigh/Mie/Raman (RMR) lidar measurements of cirrus mammatus in the night of 07-08 June 2006 at Shigaraki Observatory (34.85°N, 136.10°E, Japan). Coincident observations from the VHF (46.5 MHz) MU radar in range imaging (FII) mode revealed the presence of downward developing turbulent layers and oscillatory vertical wind perturbations (+/-0.7 m/s) near the cirrus cloud base and in the mammatus environment. Moreover, simultaneous radiosonde data showed the presence of a dry and weakly stable layer underneath the cirrus. Our analysis suggests that turbulence and mammatus were generated by convective overturns due to evaporative cooling in the subcloud region. The cooling was likely the consequence of sublimation of ice crystals below the cloud base due to either precipitation or, more likely, spontaneous mixing of the saturated air and the dry air through the cloud-base detrainment instability (CDI) mechanism at the cloud base. Clear air downdrafts measured by the MU radar were associated with the descending mammatus lobes and clear air updrafts were observed between the lobes. Consequently, in addition to a possible negative buoyancy of the cloudy air, the cloudy air might have been pushed down by the downdrafts of the "upside-down" convective instability and pushed up by the updrafts to form mammatus lobes.

  2. Turbulent transport across an interface between dry and humid air in a stratified environment

    NASA Astrophysics Data System (ADS)

    Gallana, Luca; de Santi, Francesca; di Savino, Silvio; Iovieno, Michele; Ricchiardone, Renzo; Tordella, Daniela

    2014-11-01

    The transport of energy and water vapor across a thin layer which separates two decaying isotropic turbulent flows with different kinetic energy and humidity is considered. The interface is placed in a shearless stratified environment in temporal decay. This system reproduces a few aspects of small scale turbulent transport across a dry air/moist air interface in an atmospheric like context. In our incompressible DNS at Reλ = 250 , Boussinesq's approximation is used for momentum and energy transport while the vapor is modeled as a passive scalar (Kumar, Schumacher & Shaw 2014). We investigated different stratification levels with an initial Fr between 0.8 and 8 in presence of a kinetic energy ratio equal to 7. As the buoyancy term becomes of the same order of the inertial ones, a spatial redistribution of kinetic energy, dissipation and vapor concentration is observed. This eventually leads to the onset of a well of kinetic energy in the low energy side of the mixing layer which blocks the entrainment of dry air. Results are discussed and compared with laboratory and numerical experiments. A posteriori estimates of the eventual compression/expansion of fluid particles inside the interfacial mixing layer are given (Nance & Durran 1994).

  3. Fast Hydrogen-Air Flames for Turbulence Driven Deflagration to Detonation Transition

    NASA Astrophysics Data System (ADS)

    Chambers, Jessica; Ahmed, Kareem

    2016-11-01

    Flame acceleration to Detonation produces several combustion modes as the Deflagration-to-Detonation Transition (DDT) is initiated, including fast deflagration, auto-ignition, and quasi-detonation. Shock flame interactions and turbulence levels in the reactant mixture drive rapid flame expansion, formation of a leading shockwave and post-shock conditions. An experimental study to characterize the developing shock and flame front behavior of propagating premixed hydrogen-air flames in a square channel is presented. To produce each flame regime, turbulence levels and flame propagation velocity are controlled using perforated plates in several configurations within the experimental facility. High speed optical diagnostics including Schlieren and Particle Image Velocimetry are used to capture the flow field. In-flow pressure measurements acquired post-shock, detail the dynamic changes that occur in the compressed gas directly ahead of the propagating flame. Emphasis on characterizing the turbulent post-shock environment of the various flame regimes helps identify the optimum conditions to initiate the DDT process. The study aims to further the understanding of complex physical mechanisms that drive transient flame conditions for detonation initiation. American Chemical Society.

  4. Immunochemical approach to indoor aeroallergen quantitation with a new volumetric air sampler: studies with mite, roach, cat, mouse, and guinea pig antigens

    SciTech Connect

    Swanson, M.C.; Agarwal, M.K.; Reed, C.E.

    1985-11-01

    We describe a new high-volume air sampler for determining antigen concentrations in homes and illustrate its use for quantitating airborne house dust mite, cat, cockroach, mouse, and guinea pig antigens. The concentration of house dust-mite antigen was similar from houses in Rochester, Minn. and tenement apartments in Harlem, N. Y., but cockroach and mouse urinary proteins were present only in Harlem. The amount of cat or guinea pig antigen varied as expected with the number of pets in the home. In calm air the airborne concentration of mite and cat antigen was similar throughout the house but increased greatly in a bedroom when bedding was changed. In calm air most of the cat and mite antigens were associated with respirable particles less than 5 microns mean aerodynamic mass diameter, but in air sampled after the bedding was changed, more cat antigen was found in particles greater than 5 microns. The apparatus and technique described can provide objective data concerning the magnitude and the relative distribution and duration of suspended particles of defined sizes, which contain allergen activity.

  5. Richtmyer-Meshkov induced turbulent mixing of air-SF6 multimode discontinuous interfaces

    NASA Astrophysics Data System (ADS)

    Haas, Jean-François; Lassis, Alexandre; Montlaurent, Philippe; Rayer, Claude; Schwaederlé, Laurent

    2002-11-01

    We measure the Rayleigh-Taylor instability (RTI)-induced turbulent mixing initiated by the interaction of an incident shock wave (typically Mach 1.2 in air at atmospheric condition) with a discontinuous multimode air-SF6 interface and amplified by the subsequent shock and rarefaction waves reverberating between the mixing zone and the end plate. This experiment is carried out in a shock tube (square internal cross section 13 cm by 13 cm) and the length of the downstream section filled with SF6 is about 30 cm. Initially, the gases are separated by a nitrocellulose microfilm (0,5 µm thick) in sandwich between two fine wire grids imposing a non-linear three-dimensional perturbation of fundamental wave length 1 mm but of unknown amplitude (we estimate 0.1 to 0.3 mm). We visualize the flow with conventional schlieren and shadow systems and aim at obtaining instantaneous concentration maps using a 0,5 mm thick laser sheet (from a single pulse ruby laser providing 1 Joule during 50 ns) shining through the transparent endplate. We seed either the SF6 with olive oil droplets or the air with smoke from the combustion of incense. As previouly for a SF6-air interface, the evolution of the axial and transversal components of the velocity field will be obtained with a laser doppler velocimeter, in which case both gases are seeded. We may also present the final results of constant temperature hot wire anemometer measurements on the same flows in a Marseille shock tube which provide the evolution of the concentration. The experimental results may be compared to the calculations using turbulent modelling or two or three dimensional simulations.

  6. Velocity measurements within a shock and reshock induced air/SF6 turbulent mixing zone

    NASA Astrophysics Data System (ADS)

    Haas, Jean-Francois; Bouzgarrou, Ghazi; Bury, Yannick; Jamme, Stephane; Joly, Laurent; Shock-induced mixing Team

    2012-11-01

    A turbulent mixing zone (TMZ) is created in a shock tube (based in ISAE, DAEP) when a Mach 1.2 shock wave in air accelerates impulsively to 70 m/s an air/SF6 interface. The gases are initially separated by a 1 μm thick plastic microfilm maintained flat and parallel to the shock by two wire grids. The upper grid of square spacing 1.8 mm imposes the nonlinear initial perturbation for the Richtmyer-Meshkov instability (RMI). After interaction with a reshock and a rarefaction, the TMZ remains approximately stagnant but much more turbulent. High speed Schlieren visualizations enable the choice of abscissae for Laser Doppler Velocity (LDV) measurements. For a length of the SF6 section equal to 250 mm, the LDV abscissae are 43, 135 and 150 mm from the initial position of the interface. Because of numerous microfilm fragments in the flow and a limited number of olive oil droplets as seeding particles for the LDV, statistical convergence requires the superposition of a least 50 identical runs at each abscissa. The dependence of TMZ structure and velocity field on length of the SF6 section between 100 and 300 mm will be presented. This experimental investigation is carried out in support of modeling and multidimensional simulation efforts at CEA, DAM, DIF. Financial support from CEA is thanksfully appreciated by ISAE.

  7. Modelling low-Reynolds-number effects in the turbulent air flow over water waves

    NASA Astrophysics Data System (ADS)

    Meirink, Jan F.; Makin, Vladimir K.

    2000-07-01

    In studies of the turbulent air flow over water waves it is usually assumed that the effect of viscosity near the water surface is negligible, i.e. the Reynolds number, Re = u[low asterisk][lambda]/v, is considered to be high. However, for short waves or low wind speeds this assumption is not valid. Therefore, a second-order turbulence closure that takes into account viscous effects is used to simulate the air flow. The model shows reasonable agreement with laboratory measurements of wave-induced velocity profiles. Next, the dependence of the dimensionless energy flux from wind to waves, or growth rate, on Re is investigated. The growth rate of waves that are slow compared to the wind is found to increase strongly when Re decreases below 104, with a maximum around Re = 800. The numerical model predictions are in good agreement with analytical theories and laboratory observations. Results of the study are useful in field conditions for the short waves in the spectrum, which are particularly important for remote sensing applications.

  8. Turbulent Boundary Layer on a Finely Perforated Surface Under Conditions of Air Injection at the Expense of External Flow Resources

    NASA Astrophysics Data System (ADS)

    Kornilov, V. I.; Boiko, A. V.; Kavun, I. N.

    2015-11-01

    The characteristics of an incompressible turbulent boundary layer on a flat plate with air blown in though a finely perforated surface from an external confined flow through an input device, located on the "idle" side of the plate, have been investigated experimentally and numerically. A stable decrease in the local values of the coefficient of surface friction along the plate length that attains 85% at the end of the perforated portion is shown. The experimental and calculated data obtained point to the possibility of modeling, under earth conditions, the process of controlling a turbulent boundary layer with air injection by using the resources of an external confined flow.

  9. TECNAIRE winter field campaign: turbulent characteristics and their influence on air quality conditions

    NASA Astrophysics Data System (ADS)

    Yagüe, Carlos; Román Cascón, Carlos; Maqueda, Gregorio; Sastre, Mariano; Arrillaga, Jon A.; Artíñano, Begoña; Diaz-Ramiro, Elías; Gómez-Moreno, Francisco J.; Borge, Rafael; Narros, Adolfo; Pérez, Javier

    2016-04-01

    An urban field campaign was conducted at an air pollution hot spot in Madrid city (Spain) during winter 2015 (from 16th February to 2nd March). The zone selected for the study is a square (Plaza Fernández Ladreda) located in the southern part of the city. This area is an important intersection of several principal routes, and therefore a significant impact in the air quality of the area is found due to the high traffic density. Meteorological data (wind speed and direction, air temperature, relative humidity, pressure, precipitation and global solar radiation) were daily recorded as well as micrometeorological measurements obtained from two sonic anemometers. To characterize this urban atmospheric boundary layer (uABL), micrometeorological parameters (turbulent kinetic energy -TKE-, friction velocity -u∗- and sensible heat flux -H-) are calculated, considering 5-minute average for variance and covariance evaluations. Furthermore, synoptic atmospheric features were analyzed. As a whole, a predominant influence of high pressure systems was found over the Atlantic Ocean and western Spain, affecting Madrid, but during a couple of days (17th and 21st February) some atmospheric instability played a role. The influence of the synoptic situation and specially the evolution of the micrometeorological conditions along the day on air quality characteristics (Particulate Matter concentrations: PM10, PM2.5 and PM1, and NOx concentrations) are analyzed and shown in detail. This work has been financed by Madrid Regional Research Plan through TECNAIRE (P2013/MAE-2972).

  10. Weather in the Cockpit: Priorities, Sources, Delivery, and Needs in the Next Generation Air Transportation System

    DTIC Science & Technology

    2012-07-01

    discomfort. Extreme turbulence could cause physical injuries to pilot/ passengers who are not wearing seat belts. Clear Air Turbulence (CAT) CAT... passengers who are not wearing seat belts. Generally caused by wind shear in the atmosphere where no clouds are present. Mountain Waves Fast...ways in which our analyses could inform the design of information systems. NextGen, in its mature state, envisions pilots having control over

  11. Turbulent Transfer Coefficients and Calculation of Air Temperature inside Tall Grass Canopies in Land Atmosphere Schemes for Environmental Modeling.

    NASA Astrophysics Data System (ADS)

    Mihailovic, D. T.; Alapaty, K.; Lalic, B.; Arsenic, I.; Rajkovic, B.; Malinovic, S.

    2004-10-01

    A method for estimating profiles of turbulent transfer coefficients inside a vegetation canopy and their use in calculating the air temperature inside tall grass canopies in land surface schemes for environmental modeling is presented. The proposed method, based on K theory, is assessed using data measured in a maize canopy. The air temperature inside the canopy is determined diagnostically by a method based on detailed consideration of 1) calculations of turbulent fluxes, 2) the shape of the wind and turbulent transfer coefficient profiles, and 3) calculation of the aerodynamic resistances inside tall grass canopies. An expression for calculating the turbulent transfer coefficient inside sparse tall grass canopies is also suggested, including modification of the corresponding equation for the wind profile inside the canopy. The proposed calculations of K-theory parameters are tested using the Land Air Parameterization Scheme (LAPS). Model outputs of air temperature inside the canopy for 8 17 July 2002 are compared with micrometeorological measurements inside a sunflower field at the Rimski Sancevi experimental site (Serbia). To demonstrate how changes in the specification of canopy density affect the simulation of air temperature inside tall grass canopies and, thus, alter the growth of PBL height, numerical experiments are performed with LAPS coupled with a one-dimensional PBL model over a sunflower field. To examine how the turbulent transfer coefficient inside tall grass canopies over a large domain represents the influence of the underlying surface on the air layer above, sensitivity tests are performed using a coupled system consisting of the NCEP Nonhydrostatic Mesoscale Model and LAPS.


  12. An experimental validation of a turbulence model for air flow in a mining chamber

    NASA Astrophysics Data System (ADS)

    Branny, M.; Karch, M.; Wodziak, W.; Jaszczur, M.; Nowak, R.; Szmyd, J. S.

    2014-08-01

    In copper mines, excavation chambers are ventilated by jet fans. A fan is installed at the inlet of the dead-end chamber, which is usually 20-30m long. The effectiveness of ventilation depends on the stream range generated by the fan. The velocity field generated by the supply air stream is fully three-dimensional and the flow is turbulent. Currently, the parameters of 3D air flows are determined using the CFD approach. This paper presents the results of experimental testing and numerical simulations of airflow in a laboratory model of a blind channel, aired by a forced ventilation system. The aim of the investigation is qualitative and quantitative verification of computer modelling data. The analysed layout is a geometrically re-scaled and simplified model of a real object. The geometrical scale of the physical model is 1:10. The model walls are smooth, the channel cross-section is rectangular. Measurements were performed for the average airflow velocity in the inlet duct equal 35.4m/s, which gives a Reynolds number of about 180 000. The components of the velocity vector were measured using the Particle Image Velocimetry approach. The numerical procedures presented in this paper use two turbulence models: the standard k-ɛ model and the Reynolds Stress model. The experimental results have been compared against the results of numerical simulations. In the investigated domain of flow - extending from the air inlet to the blind wall of the chamber - we can distinguish two zones with recirculating flows. The first, reaching a distance of about lm from the inlet is characterized by intense mixing of air. A second vortex is formed into a distance greater than lm from the inlet. Such an image of the velocity field results from both the measurements and calculations. Based on this study, we can conclude that the RSM model provides better predictions than the standard k-ɛ model. Good qualitative agreement is achieved between Reynolds Stress model predictions and measured

  13. Turbulent mass flux closure modeling for variable density turbulence in the wake of an air-entraining transom stern

    NASA Astrophysics Data System (ADS)

    Hendrickson, Kelli; Yue, Dick

    2016-11-01

    This work presents the development and a priori testing of closure models for the incompressible highly-variable density turbulent (IHVDT) flow in the near wake region of a transom stern. This complex, three-dimensional flow includes three regions with distinctly different flow behavior: (i) the convergent corner waves that originate from the body and collide on the ship center plane; (ii) the "rooster tail" that forms from the collision; and (iii) the diverging wave train. The characteristics of these regions involve violent free-surface flows and breaking waves with significant turbulent mass flux (TMF) at Atwood number At = (ρ2 -ρ1) / (ρ2 +ρ1) 1 for which there is little guidance in turbulence closure modeling for the momentum and scalar transport along the wake. Utilizing datasets from high-resolution simulations of the near wake of a canonical three-dimensional transom stern using conservative Volume-of-Fluid (cVOF), implicit Large Eddy Simulation (iLES), and Boundary Data Immersion Method (BDIM), we develop explicit algebraic turbulent mass flux closure models that incorporate the most relevant physical processes. Performance of these models in predicting the turbulent mass flux in all three regions of the wake will be presented. Office of Naval Research.

  14. Experimental modeling of air blowing into a turbulent boundary layer using an external pressure flow

    NASA Astrophysics Data System (ADS)

    Kornilov, V. I.; Boiko, A. V.

    2016-10-01

    We have experimentally investigated the characteristics of an incompressible turbulent boundary layer on a plane plate upon the passive blowing of air through a fine-perforated surface and flushing it by supplying an external pressure flow through a wind tunnel using an intake device equipped with an attachment for draining the boundary layer on the inactive side of the plate. A stable decrease in the local values of the surface coefficient of friction, which reaches 80% at the end of the perforated region, has been detected over the length of the plate. The possibility of controlling surface friction by changing the velocity of the external flow and selecting the meshes and filters at the inlet to the flow passage has been demonstrated.

  15. Investigation of inhomogeneity and anisotropy in near ground layers of atmospheric air turbulence using image motion monitoring method

    NASA Astrophysics Data System (ADS)

    Mohammadi Razi, Ebrahim; Rasouli, Saifollah

    2017-01-01

    In this work the anisotropy and inhomogeneity of real atmospheric turbulence have been investigated using image motion monitoring and differential image motion monitoring methods. For this purpose the light beam of a point source is propagated through the atmospheric turbulence layers in horizontal path and then impinged to a telescope aperture. The telescope and point source were 350 m apart. In front of the telescope's aperture a mask consisting of four subapertures was installed. Image of the point source was formed on a sensitive CCD camera located at the focal plane of the telescope. By displacing CCD camera along the axis of telescope, four distinct images were recorded. Angle of arrival (AA) of each spot was calculated by image processing. Air turbulence causes AA to fluctuate. By comparing AA fluctuation variances of different spots in two directions isotropy and homogeneity of turbulence were studied. Results have shown that atmospheric turbulence in near ground layers is treated as an anisotropic and inhomogeneous medium. In addition, the inhomogeneity and anisotropy of turbulence decreases with the distance from earth surface.

  16. NASA Turbulence Technologies In-Service Evaluation: Delta Air Lines Report-Out

    NASA Technical Reports Server (NTRS)

    Amaral, Christian; Dickson, Steve; Watts, Bill

    2007-01-01

    Concluding an in-service evaluation of two new turbulence detection technologies developed in the Turbulence Prediction and Warning Systems (TPAWS) element of the NASA Aviation Safety and Security Program's Weather Accident Prevention Project (WxAP), this report documents Delta's experience working with the technologies, feedback gained from pilots and dispatchers concerning current turbulence techniques and procedures, and Delta's recommendations regarding directions for further efforts by the research community. Technologies evaluated included an automatic airborne turbulence encounter reporting technology called the Turbulence Auto PIREP System (TAPS), and a significant enhancement to the ability of modern airborne weather radars to predict and display turbulence of operational significance, called E-Turb radar.

  17. Computational fluid dynamics for modeling the turbulent natural convection in a double air-channel solar chimney system

    NASA Astrophysics Data System (ADS)

    Zavala-Guillén, I.; Xamán, J.; Álvarez, G.; Arce, J.; Hernández-Pérez, I.; Gijón-Rivera, M.

    2016-03-01

    This study reports the modeling of the turbulent natural convection in a double air-channel solar chimney (SC-DC) and its comparison with a single air-channel solar chimney (SC-C). Prediction of the mass flow and the thermal behavior of the SC-DC were obtained under three different climates of Mexico during one summer day. The climates correspond to: tropical savannah (Mérida), arid desert (Hermosillo) and temperate with warm summer (Mexico City). A code based on the Finite Volume Method was developed and a k-ω turbulence model has been used to model air turbulence in the solar chimney (SC). The code was validated against experimental data. The results indicate that during the day the SC-DC extracts about 50% more mass flow than the SC-C. When the SC-DC is located in Mérida, Hermosillo and Mexico City, the air-changes extracted along the day were 60, 63 and 52, respectively. The air temperature at the outlet of the chimney increased up to 33%, 38% and 61% with respect to the temperature it has at the inlet for Mérida, Hermosillo and Mexico City, respectively.

  18. DNS of a turbulent, self-igniting n-dodecane / air jet

    NASA Astrophysics Data System (ADS)

    Borghesi, Giulio; Chen, Jacqueline

    2016-11-01

    A direct numerical simulation of a turbulent, self-igniting temporal jet between n-dodecane and diluted air at p =25 bar has been conducted to clarify certain aspects of diesel engine combustion. The thermodynamics conditions were selected to result in a two-stage ignition event, in which low- and high-temperature chemical reactions play an equally important role during the ignition process. Jet parameters were tuned to yield a target ignition Damkohler number of 0.4, a value representative of conditions found in diesel spray flames. Chemical reactions were described by a 35-species reduced mechanism, including both the low- and high-temperature reaction pathways of n-dodecane. The present work focuses on the influence of low-temperature chemistry on the overall ignition transient. We also study the structure of the flames formed at the end of the autoignition transient. Recent studies on diluted dimethyl ether / air flames at pressure and temperature conditions similar to those investigated in this work revealed the existence of tetra- and penta-brachial flames, and it is of interest to determine whether similar flame structures also exist when diesel-like fuels are used.

  19. Influence of turbulent flow on the explosion parameters of micro- and nano-aluminum powder-air mixtures.

    PubMed

    Liu, Xueling; Zhang, Qi

    2015-12-15

    The environmental turbulence intensity has a significant influence on the explosion parameters of both micro- and nano-Al at the time of ignition. However, explosion research on turbulence intensity with respect to micro- and nano-Al powders is still insufficient. In this work, micro- and nano-aluminum powders were investigated via scanning electron microscopy (SEM), and their particle size distributions were measured using a laser diffraction analyzer under dispersing air pressures of 0.4, 0.6, and 0.8 MPa in a 20 L cylindrical, strong plexiglass vessel. The particle size distributions in three different mass ratio mixtures of micro- and nano-Al powders (micro-Al:nano-Al[massratio]=95:5, 90:10, and 85:15) were also measured. The results show that the agglomerate size of nano-Al powder is an order of magnitude larger than the nanoparticles' actual size. Furthermore, the turbulence intensity ranges (Urms) of the Al powder-air mixtures were measured using particle image velocimetry (PIV) under dispersing air pressures of 0.4, 0.6, and 0.8 MPa. The effect of turbulence intensity on the explosion characteristics of the micro- and nano-Al powders was investigated using a 20 L cylindrical explosion vessel. The results of micro-Al and nano-Al powder-air mixtures with a stoichiometric concentration of 337.00 g·m(-3) were discussed for the maximum explosion pressure, the maximum rate of pressure increase and the maximum effective burning velocity under the different turbulence intensity.

  20. Air-chemistry "turbulence": power-law scaling and statistical regularity

    NASA Astrophysics Data System (ADS)

    Hsu, H.-M.; Lin, C.-Y.; Guenther, A.; Tribbia, J. J.; Liu, S. C.

    2011-03-01

    With the intent to gain further knowledge on the spectral structures and statistical regularities of surface atmospheric chemistry, the chemical gases (NO, NO2, NOx, CO, SO2, and O3) and aerosol (PM10) measured at 74 air quality monitoring stations over the island of Taiwan are analyzed for the year of 2004 at hourly resolution. They represent a range of surface air quality with a mixed combination of geographic settings, and include urban/rural, coastal/inland, and plain/hill locations. In addition to the well-known semi-diurnal and diurnal oscillations, weekly, intermediate (20 ~ 30 days) and intraseasonal (30 ~ 100 days) peaks are also identified with the continuous wavelet transform (CWT). The spectra indicate power-law scaling regions for the frequencies higher than the diurnal and those lower than the diurnal with the average exponents of -5/3 and -1, respectively. These dual-exponents are corroborated with those with the detrended fluctuation analysis in the corresponding time-lag regions. After spectral coefficients from the CWT decomposition are grouped according to the spectral bands, and inverted separately, the PDFs of the reconstructed time series for the high-frequency band demonstrate the interesting statistical regularity, -3 power-law scaling for the heavy tails, consistently. Such spectral peaks, dual-exponent structures, and power-law scaling in heavy tails are intriguingly interesting, but their relations to turbulence and mesoscale variability require further investigations. This could lead to a better understanding of the processes controlling air quality.

  1. Air-chemistry "turbulence": power-law scaling and statistical regularity

    NASA Astrophysics Data System (ADS)

    Hsu, H.-M.; Lin, C.-Y.; Guenther, A.; Tribbia, J. J.; Liu, S. C.

    2011-08-01

    With the intent to gain further knowledge on the spectral structures and statistical regularities of surface atmospheric chemistry, the chemical gases (NO, NO2, NOx, CO, SO2, and O3) and aerosol (PM10) measured at 74 air quality monitoring stations over the island of Taiwan are analyzed for the year of 2004 at hourly resolution. They represent a range of surface air quality with a mixed combination of geographic settings, and include urban/rural, coastal/inland, plain/hill, and industrial/agricultural locations. In addition to the well-known semi-diurnal and diurnal oscillations, weekly, and intermediate (20 ~ 30 days) peaks are also identified with the continuous wavelet transform (CWT). The spectra indicate power-law scaling regions for the frequencies higher than the diurnal and those lower than the diurnal with the average exponents of -5/3 and -1, respectively. These dual-exponents are corroborated with those with the detrended fluctuation analysis in the corresponding time-lag regions. These exponents are mostly independent of the averages and standard deviations of time series measured at various geographic settings, i.e., the spatial inhomogeneities. In other words, they possess dominant universal structures. After spectral coefficients from the CWT decomposition are grouped according to the spectral bands, and inverted separately, the PDFs of the reconstructed time series for the high-frequency band demonstrate the interesting statistical regularity, -3 power-law scaling for the heavy tails, consistently. Such spectral peaks, dual-exponent structures, and power-law scaling in heavy tails are important structural information, but their relations to turbulence and mesoscale variability require further investigations. This could lead to a better understanding of the processes controlling air quality.

  2. Experimental Validation of a Forward Looking Interferometer for Detection of Clear Air Turbulence due to Mountain Waves

    NASA Technical Reports Server (NTRS)

    Schaffner, Philip R.; Daniels, Taumi S.; West, Leanne L.; Gimmestad, Gary G.; Lane, Sarah E.; Burdette, Edward M.; Smith, William L.; Kireev, Stanislav; Cornman, Larry; Sharman, Robert D.

    2012-01-01

    The Forward-Looking Interferometer (FLI) is an airborne sensor concept for detection and estimation of potential atmospheric hazards to aircraft. The FLI concept is based on high-resolution Infrared Fourier Transform Spectrometry technologies that have been developed for satellite remote sensing. The FLI is being evaluated for its potential to address multiple hazards, during all phases of flight, including clear air turbulence, volcanic ash, wake vortices, low slant range visibility, dry wind shear, and icing. In addition, the FLI is being evaluated for its potential to detect hazardous runway conditions during landing, such as wet or icy asphalt or concrete. The validation of model-based instrument and hazard simulation results is accomplished by comparing predicted performance against empirical data. In the mountain lee wave data collected in the previous FLI project, the data showed a damped, periodic mountain wave structure. The wave data itself will be of use in forecast and nowcast turbulence products such as the Graphical Turbulence Guidance and Graphical Turbulence Guidance Nowcast products. Determining how turbulence hazard estimates can be derived from FLI measurements will require further investigation.

  3. Modeling 3D conjugate heat and mass transfer for turbulent air drying of Chilean papaya in a direct contact dryer

    NASA Astrophysics Data System (ADS)

    Lemus-Mondaca, Roberto A.; Vega-Gálvez, Antonio; Zambra, Carlos E.; Moraga, Nelson O.

    2017-01-01

    A 3D model considering heat and mass transfer for food dehydration inside a direct contact dryer is studied. The k- ɛ model is used to describe turbulent air flow. The samples thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. FVM, SIMPLE algorithm based on a FORTRAN code are used. Results unsteady velocity, temperature, moisture, kinetic energy and dissipation rate for the air flow are presented, whilst temperature and moisture values for the food also are presented. The validation procedure includes a comparison with experimental and numerical temperature and moisture content results obtained from experimental data, reaching a deviation 7-10 %. In addition, this turbulent k- ɛ model provided a better understanding of the transport phenomenon inside the dryer and sample.

  4. The Calern atmospheric turbulence station

    NASA Astrophysics Data System (ADS)

    Chabé, Julien; Ziad, Aziz; Fantéï-Caujolle, Yan; Aristidi, Éric; Renaud, Catherine; Blary, Flavien; Marjani, Mohammed

    2016-07-01

    From its long expertise in Atmospheric Optics, the Observatoire de la Côte d'Azur and the J.L. Lagrange Laboratory have equipped the Calern Observatory with a station of atmospheric turbulence measurement (CATS: Calern Atmospheric Turbulence Station). The CATS station is equipped with a set of complementary instruments for monitoring atmospheric turbulence parameters. These new-generation instruments are autonomous within original techniques for measuring optical turbulence since the first meters above the ground to the borders of the atmosphere. The CATS station is also a support for our training activities as part of our Masters MAUCA and OPTICS, through the organization of on-sky practical works.

  5. Correlation of flame speed with stretch in turbulent premixed methane/air flames

    SciTech Connect

    Chen, J.H.; Im, H.G.

    1998-03-01

    Direct numerical simulations of two-dimensional unsteady premixed methane/air flames are performed to determine the correlation of flame speed with stretch over a wide range of curvatures and strain rates generated by intense two-dimensional turbulence. Lean and stoichiometric premixtures are considered with a detailed C{sub 1}-mechanism for methane oxidation. The computed correlation shows the existence of two distinct stable branches. It further shows that exceedingly large negative values of stretch can be obtained solely through curvature effects which give rise to an overall nonlinear correlation of the flame speed with stretch. Over a narrower stretch range, {minus}1 {le} Ka {le} 1, which includes 90% of the sample, the correlation is approximately linear, and hence, the asymptotic theory for stretch is practically applicable. Overall, one-third of the sample has negative stretch. In this linear range, the Markstein number associated with the positive branch is determined and is consistent with values obtained from comparable steady counterflow computations. In addition to this conventional positive branch, a negative branch is identified. This negative branch occurs when a flame cusp, with a center of curvature in the burnt gases, is subjected to intense compressive strain, resulting in a negative displacement speed. Negative flame speeds are also encountered for extensive tangential strain rates exceeding a Karlovitz number of unity, a value consistent with steady counterflow computations.

  6. Relationships between stratospheric clear air turbulence and synoptic meteorological parameters over the western United States between 12-20 km altitude

    NASA Technical Reports Server (NTRS)

    Scoggins, J. R.; Clark, T. L.; Possiel, N. C.

    1975-01-01

    Procedures for forecasting clear air turbulence in the stratosphere over the western United States from rawinsonde data are described and results presented. Approaches taken to relate meteorological parameters to regions of turbulence and nonturbulence encountered by the XB-70 during 46 flights at altitudes between 12-20 km include: empirical probabilities, discriminant function analysis, and mountainwave theory. Results from these techniques were combined into a procedure to forecast regions of clear air turbulence with an accuracy of 70-80 percent. A computer program was developed to provide an objective forecast directly from the rawinsonde sounding data.

  7. The study of droplet-laden turbulent air-flow over waved water surface by direct numerical simulation

    NASA Astrophysics Data System (ADS)

    Druzhinin, Oleg A.; Troitskaya, Yuliya I.; Zilitinkevich, Sergej S.

    2016-04-01

    The detailed knowledge of the interaction of wind with surface water waves is necessary for correct parameterization of turbulent exchange at the air-sea interface in prognostic models. At sufficiently strong winds, sea-spray-generated droplets interfere with the wind-waves interaction. The results of field experiments and laboratory measurements (Andreas et al., JGR 2010) show that mass fraction of air-borne spume water droplets increases with the wind speed and their impact on the carrier air-flow may become significant. Phenomenological models of droplet-laden marine atmospheric boundary layer (Kudryavtsev & Makin, Bound.-Layer Met. 2011) predict that droplets significantly increase the wind velocity and suppress the turbulent air stress. The results of direct numerical simulation (DNS) of a turbulent particle-laden Couette flow over a flat surface show that inertial particles may significantly reduce the carrier flow vertical momentum flux (Richter & Sullivan, GRL 2013). The results also show that in the range of droplet sizes typically found near the air-sea interface, particle inertial effects are significant and dominate any particle-induced stratification effects. However, so far there has been no attempt to perform DNS of a droplet-laden air-flow over waved water surface. In this report, we present results of DNS of droplet-laden, turbulent Couette air-flow over waved water surface. The carrier, turbulent Couette-flow configuration in DNS is similar to that used in previous numerical studies (Sullivan et al., JFM 2000, Shen et al., JFM 2010, Druzhinin et al., JGR 2012). Discrete droplets are considered as non-deformable solid spheres and tracked in a Lagrangian framework, and their impact on the carrier flow is modeled with the use of a point-force approximation. The droplets parameters in DNS are matched to the typical known spume-droplets parameters in laboratory and field experiments. The DNS results show that both gravitational settling of droplets and

  8. [Air quality in schools - classroom levels of carbon dioxide (CO2), volatile organic compounds (VOC), aldehydes, endotoxins and cat allergen].

    PubMed

    Fromme, H; Heitmann, D; Dietrich, S; Schierl, R; Körner, W; Kiranoglu, M; Zapf, A; Twardella, D

    2008-02-01

    Children are assumed to be more vulnerable to health hazards and spend a large part of their time in schools. To assess the exposure situation in this microenvironment, we evaluated the indoor air quality in winter 2004/5 in 92 classrooms, and in 75 classrooms in summer 2005 in south Bavaria, Germany. Indoor air climate parameters (temperature, relative humidity), carbon dioxide (CO2) and various volatile organic compounds, aldehydes and ketones were measured. Additionally, cat allergen (Fel d1) and endotoxin (LAL-test) were analysed in the settled dust of school rooms. Data on room and building characteristics were collected by use of a standardised form. Only data collected during teaching hours were considered in analysis. The median indoor CO2 concentration in the classrooms ranged in the winter and summer period from 598 to 4 172 ppm and 480 to 1 875 ppm, respectively. While during the winter period in 92% of the classrooms the CO2 daily medians went above 1 000 ppm, the percentage of classrooms with increased CO2 concentration fell to 28% in summer. In winter, in 60% of classes the daily median CO2 concentration exceeded 1 500 ppm, while in summer this threshold was reached by only 9%. A high concentration of CO2 was associated with a high number of pupils, a low room surface area and a low room volume. The levels of total volatile organic compounds (TVOC) in classrooms ranged between 110 and 1 000 microg/m3 (median in winter 345 microg/m3, in summer 260 microg/m3). Acetone, formaldehyde and acetaldehyde were measured in concentrations from 14.0 to 911 microg/m3, from 3.1 to 46.1 microg/m3, and from 2.9 to 78 microg/m3, respectively. The other aldehydes were detected in minor amounts only. The median Fel d1 level in winter was 485 ng/g dust (20 to 45 160 ng/g) and in summer it was 417 ng/g (40-7 470 ng/g). We observed no marked differences between the two sampling periods and between smooth floors and rooms with carpeted floors. No differences were found

  9. High-Reynolds-number turbulent-boundary-layer wall pressure fluctuations with skin-friction reduction by air injection.

    PubMed

    Winkel, Eric S; Elbing, Brian R; Ceccio, Steven L; Perlin, Marc; Dowling, David R

    2008-05-01

    The hydrodynamic pressure fluctuations that occur on the solid surface beneath a turbulent boundary layer are a common source of flow noise. This paper reports multipoint surface pressure fluctuation measurements in water beneath a high-Reynolds-number turbulent boundary layer with wall injection of air to reduce skin-friction drag. The experiments were conducted in the U.S. Navy's Large Cavitation Channel on a 12.9-m-long, 3.05-m-wide hydrodynamically smooth flat plate at freestream speeds up to 20 ms and downstream-distance-based Reynolds numbers exceeding 200 x 10(6). Air was injected from one of two spanwise slots through flush-mounted porous stainless steel frits (approximately 40 microm mean pore diameter) at volume flow rates from 17.8 to 142.5 l/s per meter span. The two injectors were located 1.32 and 9.78 m from the model's leading edge and spanned the center 87% of the test model. Surface pressure measurements were made with 16 flush-mounted transducers in an "L-shaped" array located 10.7 m from the plate's leading edge. When compared to no-injection conditions, the observed wall-pressure variance was reduced by as much as 87% with air injection. In addition, air injection altered the inferred convection speed of pressure fluctuation sources and the streamwise coherence of pressure fluctuations.

  10. Spatiotemporally resolved characteristics of a gliding arc discharge in a turbulent air flow at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas; Aldén, Marcus; Larsson, Anders; Kusano, Yukihiro; Li, Zhongshan

    2017-01-01

    A gliding arc discharge was generated in a turbulent air flow at atmospheric pressure driven by a 35 kHz alternating current (AC) electric power. The spatiotemporally resolved characteristics of the gliding arc discharge, including glow-type discharges, spark-type discharges, short-cutting events and transitions among the different types of discharges, were investigated using simultaneously optical and electrical diagnostics. The glow-type discharge shows sinusoidal-like voltage and current waveforms with a peak current of hundreds of milliamperes. The frequency of the emission intensity variation of the glow-type discharge is the same as that of the electronic power dissipated in the plasma column. The glow-type discharge can transfer into a spark discharge characterized by a sharp peak current of several amperes and a sudden increase of the brightness in the plasma column. Transitions can also be found to take place from spark-type discharges to glow-type discharges. Short-cutting events were often observed as the intermediate states formed during the spark-glow transition. Three different types of short-cutting events have been observed to generate new current paths between two plasma channel segments, and between two electrodes, as well as between the channel segment and the electrodes, respectively. The short-cut upper part of the plasma column that was found to have no current passing through can be detected several hundreds of microseconds after the short-cutting event. The voltage recovery rate, the period of AC voltage-driving signal, the flow rates and the rated input powers were found to play an important role in affecting the transitions among the different types of discharges.

  11. Measurements of soot, OH, and PAH concentrations in turbulent ethylene/air jet flames

    SciTech Connect

    Lee, Seong-Young; Turns, Stephen R.; Santoro, Robert J.

    2009-12-15

    This paper presents results from an investigation of soot formation in turbulent, non-premixed, C{sub 2}H{sub 4}/air jet flames. Tests were conducted using a H{sub 2}-piloted burner with fuel issuing from a 2.18 mm i.d. tube into quiescent ambient air. A range of test conditions was studied using the initial jet velocity (16.2-94.1 m/s) as a parameter. Fuel-jet Reynolds numbers ranged from 4000 to 23,200. Planar laser-induced incandescence (LII) was employed to determine soot volume fractions, and laser-induced fluorescence (LIF) was used to measure relative hydroxyl radical (OH) concentrations and polycyclic aromatic hydrocarbons (PAHs) concentrations. Extensive information on the structure of the soot and OH fields was obtained from two-dimensional imaging experiments. Quantitative measurements were obtained by employing the LII and LIF techniques independently. Imaging results for soot, OH, and PAH show the existence of three soot formation/oxidation regions: a rapid soot growth region, in which OH and soot particles lie in distinctly different radial locations; a mixing-dominated region controlled by large-scale motion; and a soot-oxidation region in which the OH and soot fields overlap spatially, resulting in the rapid oxidation of soot particles. Detailed quantitative analyzes of soot volume fractions and OH and soot zone thicknesses were performed along with the temperature measurement using the N{sub 2}-CARS system. Measurements of OH and soot zone thicknesses show that the soot zone thickness increases linearly with axial distance in the soot formation region, whereas the OH zone thickness is nearly constant in this region. The OH zone thickness then rapidly increases with downstream distance and approximately doubles in the soot-oxidation region. Probability density functions also were obtained for soot volume fractions and OH concentrations. These probability density functions clearly define the spatial relationships among the OH, PAH concentrations, the

  12. Prevalence of Toxoplasma gondii antibodies in cats in the western part of Great Buenos Aires, Argentina, 1993.

    PubMed

    Fernández, F; Ouviña, G; Clot, E; Fernandes Guido, R; Codoni, C

    1995-08-01

    The serological prevalence of Toxoplasma gondii was determined, using indirect haemagglutination assay, in the sera of 169 cats. Classification by age, sex, alimentary, hunting and roaming habits was made in conjunction with the number of cats living in each house. An important prevalence was detected (19.5%) from 1 year of age and statistical significance was found in those animals that had predatory habits or lived in groups.

  13. Power spectral measurements of clear-air turbulence to long wavelengths for altitudes up to 14,000 meters

    NASA Technical Reports Server (NTRS)

    Murrow, H. N.; Mccain, W. E.; Rhyne, R. H.

    1982-01-01

    Measurements of three components of clear air atmospheric turbulence were made with an airplane incorporating a special instrumentation system to provide accurate data resolution to wavelengths of approximately 12,500 m (40,000 ft). Flight samplings covered an altitude range from approximately 500 to 14,000 m (1500 to 46,000 ft) in various meteorological conditions. Individual autocorrelation functions and power spectra for the three turbulence components from 43 data runs taken primarily from mountain wave and jet stream encounters are presented. The flight location (Eastern or Western United States), date, time, run length, intensity level (standard deviation), and values of statistical degrees of freedom for each run are provided in tabular form. The data presented should provide adequate information for detailed meteorological correlations. Some time histories which contain predominant low frequency wave motion are also presented.

  14. Simultaneous measurements of air-sea gas transfer velocity and near surface turbulence at low to moderate winds (Invited)

    NASA Astrophysics Data System (ADS)

    Wang, B.; Liao, Q.; Fillingham, J. H.; Bootsma, H. A.

    2013-12-01

    Parameterization of air-sea gas transfer velocity was routinely made with wind speed. Near surface turbulent dissipation rate has been shown to have better correlation with the gas transfer velocity in a variety of aquatic environments (i.e., the small eddy model) while wind speed is low to moderate. Wind speed model may underestimate gas transfer velocity at low to moderate winds when the near surface turbulence is produced by other environmental forcing. We performed a series of field experiments to measure the CO2 transfer velocity, and the statistics of turbulence immediately below the air-water interface using a novel floating PIV and chamber system. The small eddy model was evaluated and the model coefficient was found to be a non-constant, and it varies with the local turbulent level (figure 1). Measure results also suggested an appropriate scaling of the vertical dissipation profile immediately below the interface under non-breaking conditions, which can be parameterized by the wind shear, wave height and wave age (figure 2). Figure 1. Relation between the coefficient of the small eddy model and dissipation rate. The data also include Chu & Jirka (2003) and Vachon et al. (2010). The solid regression line: α = 0.188log(ɛ)+1.158 Figure 2. Non-dimensional dissipation profiles. Symbols: measured data with the floating PIV. Solid line: regression of measured data with a -0.79 decaying rate. Dash line with -2 slope: Terray et al. (1996) relation. Dash line with two layer structure: Siddiqui & Loewen (2007) relation.

  15. TOTAL: a rocket-borne instrument for high resolution measurements of neutral air turbulence during DYANA

    NASA Astrophysics Data System (ADS)

    Hillert, W.; Lübken, F.-J.; Lehmacher, G.

    1994-12-01

    An improved version of a rocket-borne instrument ('TOTAL'), optimized for high resolution measurements of relative density variations, was successfully employed during the DYANA campaign in winter 1990. Both the inertial-convective subrange and the viscous-diffusive subrange of turbulence were observed in the power spectra derived from density fluctuations. An extended spectral model which comprises both subranges has been used to analyse the data. In this paper we present altitude profiles of turbulent parameters, such as turbulent energy dissipation rates ɛ and turbulent diffusion coefficients K, which were derived from a total of eight successfully launched instruments at high (Andoya, 69°N) and middle (Biscarosse, 44°N) latitudes. The limitations of the measurement technique as well as instrumental errors are discussed. The results mainly show small values of ɛ and K throughout the whole campaign period. The turbopause was found at an altitude of 95 ± 3 km.

  16. Controlled simulation of optical turbulence in a temperature gradient air chamber

    NASA Astrophysics Data System (ADS)

    Toselli, Italo; Wang, Fei; Korotkova, Olga

    2016-05-01

    Atmospheric turbulence simulator is built and characterized for in-lab optical wave propagation with controlled strength of the refractive-index fluctuations. The temperature gradients are generated by a sequence of heat guns with controlled individual strengths. The temperature structure functions are measured in two directions transverse to propagation path with the help of a thermocouple array and used for evaluation of the corresponding refractive-index structure functions of optical turbulence.

  17. Urban Turbulence and Wind Gusts for Micro Air Vehicle Bio-inspired Designs

    DTIC Science & Technology

    2011-03-01

    Kundu , P. K. Fluid Mechanics , Academic Press, Inc.: San Diego, CA, 1990, pp. 638. Nelson, M. A.; Pardyjak, E. R.; Klewicki, J. C.; Pol, S. U...the fluid . It is heavily influenced by boundary conditions. There is no official definition of turbulence. Most modern textbooks just list some of...the properties of turbulent flow ( Kundu , 1990; Shivamoggi, 1998) such as the following: • Large fluctuations about the mean values • Enhanced rates

  18. Reprint of: A numerical modelling of gas exchange mechanisms between air and turbulent water with an aquarium chemical reaction

    NASA Astrophysics Data System (ADS)

    Nagaosa, Ryuichi S.

    2014-08-01

    This paper proposes a new numerical modelling to examine environmental chemodynamics of a gaseous material exchanged between the air and turbulent water phases across a gas-liquid interface, followed by an aquarium chemical reaction. This study uses an extended concept of a two-compartment model, and assumes two physicochemical substeps to approximate the gas exchange processes. The first substep is the gas-liquid equilibrium between the air and water phases, A(g)⇌A(aq), with Henry's law constant H. The second is a first-order irreversible chemical reaction in turbulent water, A(aq)+H2O→B(aq)+H+ with a chemical reaction rate κA. A direct numerical simulation (DNS) technique has been employed to obtain details of the gas exchange mechanisms and the chemical reaction in the water compartment, while zero velocity and uniform concentration of A is considered in the air compartment. The study uses the different Schmidt numbers between 1 and 8, and six nondimensional chemical reaction rates between 10(≈0) to 101 at a fixed Reynolds number. It focuses on the effects of the Schmidt number and the chemical reaction rate on fundamental mechanisms of the gas exchange processes across the interface.

  19. A numerical modelling of gas exchange mechanisms between air and turbulent water with an aquarium chemical reaction

    NASA Astrophysics Data System (ADS)

    Nagaosa, Ryuichi S.

    2014-01-01

    This paper proposes a new numerical modelling to examine environmental chemodynamics of a gaseous material exchanged between the air and turbulent water phases across a gas-liquid interface, followed by an aquarium chemical reaction. This study uses an extended concept of a two-compartment model, and assumes two physicochemical substeps to approximate the gas exchange processes. The first substep is the gas-liquid equilibrium between the air and water phases, A(g)⇌A(aq), with Henry's law constant H. The second is a first-order irreversible chemical reaction in turbulent water, A(aq)+H2O→B(aq)+H+ with a chemical reaction rate κA. A direct numerical simulation (DNS) technique has been employed to obtain details of the gas exchange mechanisms and the chemical reaction in the water compartment, while zero velocity and uniform concentration of A is considered in the air compartment. The study uses the different Schmidt numbers between 1 and 8, and six nondimensional chemical reaction rates between 10(≈0) to 101 at a fixed Reynolds number. It focuses on the effects of the Schmidt number and the chemical reaction rate on fundamental mechanisms of the gas exchange processes across the interface.

  20. Characterization of flame front surfaces in turbulent premixed methane/air combustion

    SciTech Connect

    Smallwood, G.J.; Guelder, Oe.L.; Snelling, D.R.; Deschamps, B.M.; Goekalp, I.

    1995-06-01

    A detailed experimental investigation of the application of fractal geometry concepts in determining the turbulent burning velocity in the wrinkled flame regime of turbulent premixed combustion was conducted. The fractal dimension and cutoff scales were determined for six different turbulent flames in the wrinkled flame regime, where the turbulence intensity, turbulent length scale, and equivalence ratio were varied. Unlike previous reports, it has proved possible to obtain the fractal dimension and inner and outer cutoffs from individual flame images. From this individual data, the pdf distributions of all three fractal parameters, along with the distribution of the predicted increase in surface area, may be determined. The analysis of over 300 flame images for each flame condition provided a sufficient sample size to accurately define the pdf distributions and their means. However, the predicted S{sub T}/S{sub L}, calculated using fractal parameters, was significantly below the measured values. For conical flames, a geometrical modification factor was employed to predict S{sub T}/S{sub L}, however, this did little to improve the predictions. There appeared to be no dependence of the predicted S{sub T}/S{sub L} on the approach flow turbulence. The cutoffs did not seem to vary significantly with any of the length scales in the approach flow turbulence, although the fractal dimension did appear to have a weak dependence on u{prime}/S{sub L} and Re{sub {lambda}}. The probable reasons that fractal geometry does not correctly predict S{sub T}/S{sub L} are that S{sub T}/S{sub L} = A{sub w}/A{sub 0} does not hold in wrinkled turbulent premixed flames, that the flame front surface cannot be described by a single scaling exponent, or that these are not wrinkled flames. S{sub T} = turbulent burning velocity, S{sub L} = laminar burning velocity, A{sub w} = wrinkled flame surface area, and A{sub 0} = flow cross section area.

  1. Using Empirical Mode Decomposition to Filter Out Non-turbulent Contributions to Air-Sea Fluxes

    NASA Astrophysics Data System (ADS)

    Martins, Luís Gustavo N.; Miller, Scott D.; Acevedo, Otávio C.

    2017-04-01

    A methodology based on Empirical mode decomposition (EMD) was used to filter out non-turbulent motions from measurements of atmospheric turbulence over the sea, aimed at reducing their contribution to eddy-covariance (EC) estimates of turbulent fluxes. The proposed methodology has two main objectives: (1) to provide more robust estimates of the fluxes of momentum, heat and CO_2; and (2) to reduce the number of flux intervals rejected due to non-stationarity criteria when using traditional EC data processing techniques. The method was applied to measurements from a 28-day cruise (HALOCAST 2010) in the Eastern Pacific region. Empirical mode decomposition was applied to 4-h long time series data and used to determine the cospectral gap time scale, T_{gap}. Intrinsic modes of oscillation with characteristic periods longer than the gap scale due to non-turbulent motions were assumed and filtered out. Turbulent fluxes were then calculated for sub-intervals of length T_{gap} from the filtered 4-h time series. In the HALOCAST data, the gap scale was successfully identified in 89% of the 4-h periods and had a mean of 37 s. The EMD approach resulted in the rejection of 11% of the flux intervals, which was much less than the 68% rejected when using standard filtering methods based on data non-stationarity. For momentum and sensible heat fluxes, the averaged difference in flux magnitude between the traditional and EMD approaches was small (3 and 1%, respectively). For the CO_2 flux, the magnitude of EMD flux estimates was on average 16% less than fluxes estimated from linear detrended 10-min time series. These results provide evidence that the EMD method can be used to reduce the effects of non-turbulent correlations from flux estimates.

  2. Comparing air-sea turbulent fluxes in reanalyses and climate models - a new framework

    NASA Astrophysics Data System (ADS)

    Gulev, S.; Tilinina, N.; Belyaev, K.

    2013-12-01

    Reanalyses fluxes and flux-related variables at high temporal resolution are widely used for forcing ocean general circulation models, case studies and estimation of regional energy budgets. We suggest a new approach for comparative assessment of fluxes in reanalyses and models based on application of modified Fisher-Tippett (MFT) distribution to turbulent heat fluxes. Two comparisons were performed - using direct surface turbulent flux output from different products (NCEP, NCEP-DOE, NCEP-CFSR, MERRA, JRA-25, ERA-Interim) and applying a single parameterization (COARE-3) to the reanalysis state variables. These allow for distinguishing between the impact of reanalysis surface parameterizations and variables onto surface turbulent fluxes. Statistical properties of surface turbulent fluxes were intercompared in terms of the MFT distribution parameters (scale and location) and extreme flux estimates derived from the distribution tails. In all reanalyses extreme turbulent heat fluxes amount to 1500-2000 W/m2 (for the 99th percentile) and can exceed 2000 W/m2 for higher percentiles in the western boundary current extension (WBCE) regions. Different reanalyses show significantly different shape of MFT distribution, implying considerable differences in the estimates of extreme fluxes. The highest extreme turbulent latent heat fluxes are diagnosed in NCEP-DOE, ERA-Interim and NCEP-CFSR reanalyses with the smallest being in MERRA. These differences may not necessarily reflect the differences in mean values. Analysis shows that differences in statistical properties of the state variables are the major source of differences in the shape of PDF of fluxes and in the estimates of extreme fluxes while the contribution of computational schemes used in different reanalyses is minor. The strongest differences in the characteristics of probability distributions of surface fluxes between different reanalyses are found in the Southern Ocean. Importantly, climate models considerably

  3. A field study of air flow and turbulent features of advection fog

    NASA Technical Reports Server (NTRS)

    Connell, J. D.

    1979-01-01

    The setup and initial operation of a set of specialized meteorological data collection hardware are described. To study the life cycle of advection fogs at a lake test site, turbulence levels in the fog are identified, and correlated with the temperature gradients and mean wind profiles. A meteorological tower was instrumented to allow multiple-level measurements of wind and temperature on a continuous basis. Additional instrumentation was: (1)hydrothermograph, (2)microbarograph, (3)transmissometers, and (4)a boundary layer profiler. Two types of fogs were identified, and important differences in the turbulence scales were noted.

  4. Further Experiments on the Flow and Heat Transfer in a Heated Turbulent Air Jet

    NASA Technical Reports Server (NTRS)

    Corrsin, Stanley; Uberoi, Mahinder S

    1949-01-01

    Measurements have been made of the mean total-head and temperature fields in a round turbulent jet with various initial temperatures. The results show that the jet spreads more rapidly as its density becomes lower than that of the receiving medium, even when the difference is not sufficiently great to cause measurable deviations from the constant-density, dimensionless, dynamic-pressure profile function. Rough analytical considerations have given the same relative spread. The effective "turbulent Prandtl number" for a section of the fully developed jet was found to be equal to the true (laminar) Prandtl number within the accuracy of measurement. (author)

  5. Measurement of spatiotemporal phase statistics in turbulent air flow using high-speed digital holographic interferometry.

    PubMed

    Lycksam, Henrik; Sjödahl, Mikael; Gren, Per

    2010-03-10

    We describe a method of measuring spatiotemporal (ST) structure and covariance functions of the phase fluctuations in a collimated light beam propagated through a region of refractive index turbulence. The measurements are performed in a small wind tunnel, in which a turbulent temperature field is created using heated wires at the inlet of the test section. A collimated sheet of light is sent through the channel, and the phase fluctuations across the sheet are measured. The spatial phase structure function can be estimated from a series of images captured at an arbitrary frame rate by spatial phase unwrapping, whereas the ST structure function requires a time resolved measurement and a full three-dimensional unwrapping. The measured spatial phase structure function shows agreement with the Kolmogorov theory with a pronounced inertial subrange, which is taken as a validation of the method. Because of turbulent mixing in the boundary layers close to the walls of the channel, the flow will not obey the Taylor hypothesis of frozen turbulence. This can be clearly seen in the ST structure function calculated in a coordinate system that moves along with the bulk flow. At zero spatial separation, this function should always be zero according to the Taylor hypothesis, but due to the mixing effect there will be a growth in the structure function with increasing time difference depending on the rate of mixing.

  6. Sound propagation in narrow tubes including effects of viscothermal and turbulent damping with application to charge air coolers

    NASA Astrophysics Data System (ADS)

    Knutsson, Magnus; Åbom, Mats

    2009-02-01

    Charge air coolers (CACs) are used on turbocharged internal combustion engines to enhance the overall gas-exchange performance. The cooling of the charged air results in higher density and thus volumetric efficiency. It is also important for petrol engines that the knock margin increases with reduced charge air temperature. A property that is still not very well investigated is the sound transmission through a CAC. The losses, due to viscous and thermal boundary layers as well as turbulence, in the narrow cooling tubes result in frequency dependent attenuation of the transmitted sound that is significant and dependent on the flow conditions. Normally, the cross-sections of the cooling tubes are neither circular nor rectangular, which is why no analytical solution accounting for a superimposed mean flow exists. The cross-dimensions of the connecting tanks, located on each side of the cooling tubes, are large compared to the diameters of the inlet and outlet ducts. Three-dimensional effects will therefore be important at frequencies significantly lower than the cut-on frequencies of the inlet/outlet ducts. In this study the two-dimensional finite element solution scheme for sound propagation in narrow tubes, including the effect of viscous and thermal boundary layers, originally derived by Astley and Cummings [Wave propagation in catalytic converters: Formulation of the problem and finite element scheme, Journal of Sound and Vibration 188 (5) (1995) 635-657] is used to extract two-ports to represent the cooling tubes. The approximate solutions for sound propagation, accounting for viscothermal and turbulent boundary layers derived by Dokumaci [Sound transmission in narrow pipes with superimposed uniform mean flow and acoustic modelling of automobile catalytic converters, Journal of Sound and Vibration 182 (5) (1995) 799-808] and Howe [The damping of sound by wall turbulent shear layers, Journal of the Acoustical Society of America 98 (3) (1995) 1723-1730], are

  7. Experimental investigation into infrasonic emissions from atmospheric turbulence.

    PubMed

    Shams, Qamar A; Zuckerwar, Allan J; Burkett, Cecil G; Weistroffer, George R; Hugo, Derek R

    2013-03-01

    Clear air turbulence (CAT) is the leading cause of in-flight injuries and in severe cases can result in fatalities. The purpose of this work is to design and develop an infrasonic array network for early warning of clear air turbulence. The infrasonic system consists of an infrasonic three-microphone array, compact windscreens, and data management system. Past experimental efforts to detect acoustic emissions from CAT have been limited. An array of three infrasonic microphones, operating in the field at NASA Langley Research Center, on several occasions received signals interpreted as infrasonic emissions from CAT. Following comparison with current lidar and other past methods, the principle of operation, the experimental methods, and experimental data are presented for case studies and confirmed by pilot reports. The power spectral density of the received signals was found to fit a power law having an exponent of -6 to -7, which is found to be characteristics of infrasonic emissions from CAT, in contrast to findings of the past.

  8. Coal air turbine {open_quotes}CAT{close_quotes} program, Invention 604. Third quarter project report, April 1995--June 1995

    SciTech Connect

    Foster-Pegg, R.W.

    1995-07-31

    The primary objective of this {open_quotes}CAT{close_quotes} project is to complete a conceptual design of this unique new combination of existing technology with cost estimates to show that the {open_quotes}CAT{close_quotes} system offers the economic incentive with low technical risk for a plant to be built which will demonstrate its viability. The technologies involved in the components of a {open_quotes}CAT{close_quotes} plant are proven, and the integration of the components into a complete plant is the only new development activity involved. Industry and the Federal General Services Administration (GSA), require the demonstration of a {open_quotes}commercial plant{close_quotes} before the viability of a new concept is accepted. To satisfy this requirement and construction of a plant of commercially viable size in excess of 15 MW if cogeneration and above 30 MW if all power, is proposed. This plant will produce economical power and heat for the owner. The plant will operate a full commercial life and continue as an operating demonstration of the viability of the technology, gathering long term life and maintenance data, all adding to the credibility of the concept.

  9. Interpretation of combined wind profiler and aircraft-measured tropospheric winds and clear air turbulence

    NASA Technical Reports Server (NTRS)

    Thomson, D. W.; Syrett, William J.; Fairall, C. W.

    1991-01-01

    In the first experiment, it was found that wind profilers are far better suited for the detailed examination of jet stream structure than are weather balloons. The combination of good vertical resolution with not previously obtained temporal resolution reveals structural details not seen before. Development of probability-derived shear values appears possible. A good correlation between pilot reports of turbulence and wind shear was found. In the second experiment, hourly measurements of wind speed and direction obtained using two wind profiling Doppler radars during two prolonged jet stream occurrences over western Pennsylvania were analyzed. In particular, the time-variant characteristics of derived shear profiles were examined. Profiler data dropouts were studied in an attempt to determine possible reasons for the apparently reduced performance of profiling radar operating beneath a jet stream. Richardson number and wind shear statistics were examined along with pilot reports of turbulence in the vicinity of the profiler.

  10. Prevalence of Toxocara cati and other parasites in cats' faeces collected from the open spaces of public institutions: Buenos Aires, Argentina.

    PubMed

    Sommerfelt, I E; Cardillo, N; López, C; Ribicich, M; Gallo, C; Franco, A

    2006-09-10

    Toxocarosis is a worldwide parasitic infection that affects both cats and dogs. Toxocara cati (Schrank, 1788) syn. Toxocara mystax (Zeder, 1800) prevalence was studied in faeces from stray cats collected from the open spaces of public institutions of Buenos Aires city, both building and surrounding open spaces are fenced off. Of the 465 samples obtained from March to June of 2005, 58.3% were found to have parasite eggs. The following parasites were identified from the 271 positive samples: T. cati (61.2%), Cystoisospora spp. (20.3%), Trichuris spp. (17.0%), Toxascaris leonina (15.1%), Ancylostoma spp. (14%) and Aelurostrongylus abstrusus (2.6%). T. cati prevalence was 35.7% (95% confidence interval: 31.2-40.1), with a 42.2% single isolations. The most frequent combination was T. cati and Cystoisospora spp. (9%). More than half the areas studied showed over 40% prevalence. Seventy-one percent of the collected samples were fresh with a variable moist consistency and 29% were older with a dry consistency. A statistically significant association was found between sample consistency and presence of parasites (chi2 = 10.81; p = 0.001) as also between sample consistency and presence of T. cati (chi2 = 11.27; p = 0.0007). Moist consistencies were significantly different from the rest: consistency (wet or dry) versus parasites (z = 1.95; p = 0.02) (95% confidence interval: 0.004-0.203); consistency (wet or dry) versus T. cati (z = 3.25; p = 0.0006) (95% confidence interval: 0.075-0.254). The cat population that inhabits these public green spaces contaminates the environment, thus transforming them into dangerous spaces with a variable rate for the human population that spends time in these places.

  11. Numerical Study of Unsteady Properties of Ethylene/Air Turbulent Jet Diffusion Flame with Detached Eddy Simulation

    NASA Astrophysics Data System (ADS)

    Ma, Sugang; Zhong, Fengquan; Zhang, Xinyu

    2016-12-01

    In this paper, unsteady process of ignition and combustion of turbulent plane-jet diffusion flame of ethylene/air is numerically simulated with detached eddy simulation (DES) and a reduced kinetic mechanism of ethylene. The kinetic mechanism consisting of 25 species and 131 steps is reduced from a 25 species/131 steps detailed mechanism via the method of error-propagation-based directed relation graph (DRGEP). The DES results of averaged temperature profiles at varied downstream locations are compared with the DNS results of Yoo et al. and satisfactory agreement between them is found. Ignition and combustion of ethylene plane-jet diffusion flame is simulated and dynamic changes of temperature field and OH radical are obtained. The present numerical study shows that DES method with a qualified reduced mechanism of hydrocarbon fuels can effectively simulate temporal and spatial evolution of ignition and combustion process.

  12. Cat Batiks.

    ERIC Educational Resources Information Center

    Buban, Marcia H.

    1998-01-01

    Discusses an art activity where fourth-grade students created backgrounds using melted paraffin and a variety of paints for their cat batik/collage. Explains that after the students created their backgrounds, they assembled their paper cats for the collage using smaller shapes glued together and wax to add texture for fur. (CMK)

  13. Modeling of turbulent supersonic H2-air combustion with a multivariate beta PDF

    NASA Technical Reports Server (NTRS)

    Baurle, R. A.; Hassan, H. A.

    1993-01-01

    Recent calculations of turbulent supersonic reacting shear flows using an assumed multivariate beta PDF (probability density function) resulted in reduced production rates and a delay in the onset of combustion. This result is not consistent with available measurements. The present research explores two possible reasons for this behavior: use of PDF's that do not yield Favre averaged quantities, and the gradient diffusion assumption. A new multivariate beta PDF involving species densities is introduced which makes it possible to compute Favre averaged mass fractions. However, using this PDF did not improve comparisons with experiment. A countergradient diffusion model is then introduced. Preliminary calculations suggest this to be the cause of the discrepancy.

  14. Correlation of turbulent burning velocities of ethanol-air, measured in a fan-stirred bomb up to 1.2 MPa

    SciTech Connect

    Bradley, D.; Lawes, M.; Mansour, M.S.

    2011-01-15

    The turbulent burning velocity is defined by the mass rate of burning and this also requires that the associated flame surface area should be defined. Previous measurements of the radial distribution of the mean reaction progress variable in turbulent explosion flames provide a basis for definitions of such surface areas for turbulent burning velocities. These inter-relationships. in general, are different from those for burner flames. Burning velocities are presented for a spherical flame surface, at which the mass of unburned gas inside it is equal to the mass of burned gas outside it. These can readily be transformed to burning velocities based on other surfaces. The measurements of the turbulent burning velocities presented are the mean from five different explosions, all under the same conditions. These cover a wide range of equivalence ratios, pressures and rms turbulent velocities for ethanol-air mixtures. Two techniques are employed, one based on measurements of high speed schlieren images, the other on pressure transducer measurements. There is good agreement between turbulent burning velocities measured by the two techniques. All the measurement are generalised in plots of burning velocity normalised by the effective unburned gas rms velocity as a function of the Karlovitz stretch factor for different strain rate Markstein numbers. For a given value of this stretch factor a decrease in Markstein number increases the normalised burning velocity. Comparisons are made with the findings of other workers. (author)

  15. X-33 Rev-F Turbulent Aeroheating Results From Test 6817 in NASA Langley 20-Inch Mach 6 Air Tunnel and Comparisons With Computations

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.; Horvath, Thomas J.; Berry, Scott A.

    2003-01-01

    Measurements and predictions of the X-33 turbulent aeroheating environment have been performed at Mach 6, perfect-gas air conditions. The purpose of this investigation was to compare measured turbulent aeroheating levels on smooth models, models with discrete trips, and models with arrays of bowed panels (which simulate bowed thermal protections system tiles) with each other and with predictions from two Navier-Stokes codes, LAURA and GASP. The wind tunnel testing was conducted at free stream Reynolds numbers based on length of 1.8 x 10(exp 6) to 6.1 x 10(exp 6) on 0.0132 scale X-33 models at a = 40-deg. Turbulent flow was produced by the discrete trips and by the bowed panels at ill but the lowest Reynolds number, but turbulent flow on the smooth model was produced only at the highest Reynolds number. Turbulent aeroheating levels on each of the three model types were measured using global phosphor thermography and were found to agree to within .he estimated uncertainty (plus or minus 15%) of the experiment. Computations were performed at the wind tunnel free stream conditions using both codes. Turbulent aeroheating levels predicted using the LAURA code were generally 5%-10% lower than those from GASP, although both sets of predictions fell within the experimental accuracy of the wind tunnel data.

  16. Astronomy CATS

    NASA Astrophysics Data System (ADS)

    Brissenden, Gina; Prather, Edward E.; Impey, Chris

    2012-08-01

    The Center for Astronomy Education's (CAE's) NSF-funded Collaboration of Astronomy Teaching Scholars (CATS) Program is a grassroots multi-institutional effort to increase the capacity for astronomy education research and improve science literacy in the United States.Our primary target population is the 500,000 college students who each year enroll in an introductory general education (a breadth requirement for non-science majors) Earth, Astronomy, and Space Science (EASS) course (Fraknoi 2001, AGI 2006).An equally important population for our efforts is the individuals who are, or will be, teaching these students. In this chapter, we will briefly discuss the goals of CAE and CATS, the varied personnel that make up the CATS collective, the diverse projects we've undertaken, and the many challenges we have had to work through to make CATS a success.

  17. A Newly Distributed Satellite-based Global Air-sea Surface Turbulent Fluxes Data Set -- GSSTF2b

    NASA Astrophysics Data System (ADS)

    Shie, C.; Nelkin, E.; Ardizzone, J.; Savtchenko, A.; Chiu, L. S.; Adler, R. F.; Lin, I.; Gao, S.

    2010-12-01

    Accurate sea surface turbulent flux measurements are crucial to understanding the global water and energy cycle changes. Remote sensing is a valuable tool for global monitoring of these flux measurements. The GSSTF (Goddard Satellite-based Surface Turbulent Fluxes) algorithm was thus developed and applied to remote sensing research and applications. The recently revived and produced daily global (1ox1o) GSSTF2b (Version-2b) dataset (July 1987-December 2008) is currently under processing for an official distribution by NASA GES DISC (Goddard Earth Sciences Data and Information Services Center) due by the end of this month (September, 2010). Like its predecessor product GSSTF2, GSSTF2b is expected to provide the scientific community a longer-period and useful turbulent surface flux dataset for global energy and water cycle research, as well as regional and short period data analyses. We have recently been funded by the NASA/MEaSUREs Program to resume processing of the GSSTF with an objective of continually producing an up-to-date uniform and reliable dataset of sea surface turbulent fluxes, derived from improved input remote sensing data and model reanalysis, which would continue to be useful for global energy and water flux research and applications. The daily global (1ox1o) GSSTF2b dataset has lately been produced using upgraded and improved input datasets such as the Special Sensor Microwave Imager (SSM/I) Version-6 (V6) product (including brightness temperature [Tb], total precipitable water [W], and wind speed [U]) and the NCEP/DOE Reanalysis-2 (R2) product (including sea skin temperature [SKT], 2-meter air temperature [T2m], and sea level pressure [SLP]). The input datasets previously used for producing the GSSTF2 product were the SSM/I Version-4 (V4) product and the NCEP Reanalysis-1 (R1) product. The newly produced GSSTF2b was found to generally agree better with available ship measurements obtained from several field experiments in 1999 than its counterpart

  18. Turbulence detection using radiosondes: plugging the gaps in the observation of turbulence

    NASA Astrophysics Data System (ADS)

    Marlton, Graeme; Harrison, Giles; Williams, Paul; Nicoll, Keri

    2014-05-01

    Turbulence costs the airline industry tens of millions of dollars each year, through damage to aircraft and injury to passengers. Clear-air turbulence (CAT) is particularly problematic, as it cannot be detected using remote sensing methods and we lack consistent observations to validate forecast models. Here we describe two specially adapted meteorological radiosondes that are used to measure turbulence. The first sensor consists of a Hall-effect magnetometer, which uses the Earth's magnetic field as a reference point, allowing the motion of the sonde to be measured. The second consists of an accelerometer that measures the accelerations the balloon encounters. A solar radiation sensor is mounted at the top of the package, to determine whether the sonde is in cloud. Results from multiple flights over Reading, UK in different conditions, show both sensors detecting turbulent regions near jet boundaries and above cloud tops, with the accelerometer recording values in excess of 6g in these regions. Case studies will show how these observations can be used to test the performance of a selection of empirical turbulence diagnostics initialised from ERA-interim data.

  19. Accounting for observational uncertainties in the evaluation of low latitude turbulent air-sea fluxes simulated in a suite of IPSL model versions

    NASA Astrophysics Data System (ADS)

    Servonnat, Jerome; Braconnot, Pascale; Gainusa-Bogdan, Alina

    2015-04-01

    Turbulent momentum and heat (sensible and latent) fluxes at the air-sea interface are key components of the whole energetic of the Earth's climate and their good representation in climate models is of prime importance. In this work, we use the methodology developed by Braconnot & Frankignoul (1993) to perform a Hotelling T2 test on spatio-temporal fields (annual cycles). This statistic provides a quantitative measure accounting for an estimate of the observational uncertainty for the evaluation of low-latitude turbulent air-sea fluxes in a suite of IPSL model versions. The spread within the observational ensemble of turbulent flux data products assembled by Gainusa-Bogdan et al (submitted) is used as an estimate of the observational uncertainty for the different turbulent fluxes. The methodology holds on a selection of a small number of dominating variability patterns (EOFs) that are common to both the model and the observations for the comparison. Consequently it focuses on the large-scale variability patterns and avoids the possibly noisy smaller scales. The results show that different versions of the IPSL couple model share common large scale model biases, but also that there the skill on sea surface temperature is not necessarily directly related to the skill in the representation of the different turbulent fluxes. Despite the large error bars on the observations the test clearly distinguish the different merits of the different model version. The analyses of the common EOF patterns and related time series provide guidance on the major differences with the observations. This work is a first attempt to use such statistic on the evaluation of the spatio-temporal variability of the turbulent fluxes, accounting for an observational uncertainty, and represents an efficient tool for systematic evaluation of simulated air-seafluxes, considering both the fluxes and the related atmospheric variables. References Braconnot, P., and C. Frankignoul (1993), Testing Model

  20. An approach to mineral particle-air bubble interaction in turbulent flow of flotation cell

    SciTech Connect

    Lu, S.; Song, S.; Gou, J.; Pan, Y.

    1995-12-31

    The calculated potential energies of interaction between hydrophobic particle of three minerals (rhodochrosite, quartz and talc) and air bubble show that the energy of hydrophobic interaction is the dominant factor for their attachment. An attachment rate equation, integrating particle-bubble collision and adhesion by introducing a capture efficiency, has been put forward. It was found that the hydrophobic particle-bubble aggregates can not be disconnected in the bulk zone of flotation cell, whereas in the impeller zone the breakup may occur, particularly for the coarser particles captured by bubble. Finally, the flotation rate constant was estimated theoretically and verified by experiments.

  1. Predicting the Turbulent Air-Sea Surface Fluxes, Including Spray Effects, from Weak to Strong Winds

    DTIC Science & Technology

    2012-09-30

    from Moon et al. (2007) and Mueller and Veron (2009) are not much different from our main straight-line result (6) for UN10 above 20 m/s...model the air-sea drag as a consequence of just wind-wave coupling. That is, Moon et al. (2007) and Mueller and Veron (2009) modeled the surface stress... Veron evidently realized that they were predicting u* to be a linear function of UN10 in high winds.) In other words, exotic processes like sea

  2. Turbulent Mixing and Combustion for High-Speed Air-Breathing Propulsion Application

    DTIC Science & Technology

    2007-08-12

    AIR-BREATHING PROPULSION APPLICATIONS P . E. Dimotakis, Principal Investigator John K. Northrop Professor ofAeronautics and Professor of Applied Physics...performance of the device is the overall pressure coefficient, C = 2(pe- p )/(pU12), where pe and pi are the exit and inlet pressures, respectively. In...1 . O. 1 o-o p ) Fig. 6 Instantaneous passive scalar isosurfaces for a M, 0.5 top stream. 7 Fig. 7 Computed pressure coefficient on the top (solid line

  3. Finite-Difference Solution for Laminar or Turbulent Boundary Layer Flow over Axisymmetric Bodies with Ideal Gas, CF4, or Equilibrium Air Chemistry

    NASA Technical Reports Server (NTRS)

    Hamilton, H. Harris, II; Millman, Daniel R.; Greendyke, Robert B.

    1992-01-01

    A computer code was developed that uses an implicit finite-difference technique to solve nonsimilar, axisymmetric boundary layer equations for both laminar and turbulent flow. The code can treat ideal gases, air in chemical equilibrium, and carbon tetrafluoride (CF4), which is a useful gas for hypersonic blunt-body simulations. This is the only known boundary layer code that can treat CF4. Comparisons with experimental data have demonstrated that accurate solutions are obtained. The method should prove useful as an analysis tool for comparing calculations with wind tunnel experiments and for making calculations about flight vehicles where equilibrium air chemistry assumptions are valid.

  4. Cat scratch disease (image)

    MedlinePlus

    Cat scratch disease is an infectious illness associated with cat scratches, bites, or exposure to cat saliva, causing chronic swelling of the lymph nodes. Cat scratch disease is possibly the most common cause of chronic ...

  5. Cat and Dog Bites

    MedlinePlus

    ... Prevention and Wellness Staying Healthy Pets and Animals Cat and Dog Bites Cat and Dog Bites Pets and AnimalsPrevention and WellnessStaying Healthy Share Cat and Dog Bites Cat and dog bites are ...

  6. Correlation of Flame Speed with Stretch in Turbulent Premixed Methane/Air Flames

    NASA Astrophysics Data System (ADS)

    Chen, Jacqueline H.; Im, Hong G.

    1997-11-01

    Flame speed correlation with stretch is obtained from direct numerical simulations of lean to stoichiometric methane/air flames over a broad range of Karlovitz numbers. The correlation is interpreted in terms of local tangential strain rate and curvature effects. DNS results show that there exist two distinct branches in the correlation curve depending on the sign of the displacement speed. For small Karlovitz numbers with positive displacement speed, the estimated Markstein length from the DNS results agrees well with that obtained from steady strained laminar flame calculations as well as with experimental studies. Larger values of Karlovitz numbers observed in the DNS results are found to be mainly due to the effect of strong curvatures; for those cases the correlation shows nonlinear behavior. The sensitivity of the correlation to the definition of the flame front and the statistical importance of particular branches in the correlation are also discussed.

  7. Filamentation of femtosecond light pulses in the air: Turbulent cells versus long-range clusters

    SciTech Connect

    Skupin, S.; Berge, L.; Mejean, G.; Yu, J.; Kasparian, J.; Salmon, E.; Wolf, J.P.; Rodriguez, M.; Woeste, L.; Bourayou, R.; Sauerbrey, R.

    2004-10-01

    The filamentation of ultrashort pulses in air is investigated theoretically and experimentally. From the theoretical point of view, beam propagation is shown to be driven by the interplay between random nucleation of small-scale cells and relaxation to long waveguides. After a transient stage along which they vary in location and in amplitude, filaments triggered by an isotropic noise are confined into distinct clusters, called 'optical pillars', whose evolution can be approximated by an averaged-in-time two-dimensional (2D) model derived from the standard propagation equations for ultrashort pulses. Results from this model are compared with space- and time-resolved numerical simulations. From the experimental point of view, similar clusters of filaments emerge from the defects of initial beam profiles delivered by the Teramobile laser facility. Qualitative features in the evolution of the filament patterns are reproduced by the 2D reduced model.

  8. Accounting for observation uncertainties in an evaluation metric of low latitude turbulent air-sea fluxes: application to the comparison of a suite of IPSL model versions

    NASA Astrophysics Data System (ADS)

    Servonnat, Jérôme; Găinuşă-Bogdan, Alina; Braconnot, Pascale

    2016-11-01

    Turbulent momentum and heat (sensible heat and latent heat) fluxes at the air-sea interface are key components of the whole energetic of the Earth's climate. The evaluation of these fluxes in the climate models is still difficult because of the large uncertainties associated with the reference products. In this paper we present an objective metric accounting for reference uncertainties to evaluate the annual cycle of the low latitude turbulent fluxes of a suite of IPSL climate models. This metric consists in a Hotelling T 2 test between the simulated and observed field in a reduce space characterized by the dominant modes of variability that are common to both the model and the reference, taking into account the observational uncertainty. The test is thus more severe when uncertainties are small as it is the case for sea surface temperature (SST). The results of the test show that for almost all variables and all model versions the model-reference differences are not zero. It is not possible to distinguish between model versions for sensible heat and meridional wind stress, certainly due to the large observational uncertainties. All model versions share similar biases for the different variables. There is no improvement between the reference versions of the IPSL model used for CMIP3 and CMIP5. The test also reveals that the higher horizontal resolution fails to improve the representation of the turbulent surface fluxes compared to the other versions. The representation of the fluxes is further degraded in a version with improved atmospheric physics with an amplification of some of the biases in the Indian Ocean and in the intertropical convergence zone. The ranking of the model versions for the turbulent fluxes is not correlated with the ranking found for SST. This highlights that despite the fact that SST gradients are important for the large-scale atmospheric circulation patterns, other factors such as wind speed, and air-sea temperature contrast play an

  9. Laboratory investigations of the heat and momentum transfer in the stably stratified air turbulent boundary layer above the wavy surface

    NASA Astrophysics Data System (ADS)

    Sergeev, Daniil; Troitskaya, Yuliya; Vdovin, Maxim

    2015-04-01

    the spray of droplets generation, especially heat transfer. The work was supported by RFBR grants (14-05-91767, 14-08-31740, 15-35-20953) and RSF grant 14-17-00667 and by President grant for young scientists MK-3550.2014.5 References: 1. Emanuel, K. A. Sensitivity of tropical cyclones to surface exchange coefficients and a revised steady-state model incorporating eye dynamics // J. Atmos. Sci., 52(22), 3969-3976,1995. 2. Brian K. Haus, Dahai Jeong, Mark A. Donelan, Jun A. Zhang, and Ivan Savelyev Relative rates of sea-air heat transfer and frictional drag in very high winds // GEOPHYSICAL RESEARCH LETTERS, VOL. 37, L07802, doi:10.1029/2009GL042206, 2010 3. Yu. I. Troitskaya, D.A. Sergeev, A.A. Kandaurov, G.A Baidakov, M.A. Vdovin, V.I. Kazakov Laboratory and theoretical modeling of air-sea momentum transfer under severe wind conditions // JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 117, C00J21, 13 PP., 2012 doi:10.1029/2011JC007778 4. Yu.I.Troitskaya, D.A.Sergeev, A.A.Kandaurov, M.I. Vdovin, A.A. Kandaurov, E.V.Ezhova, S.S.Zilitinkevich Momentum and buoyancy exchange in a turbulent air boundary layer over a wavy water surface. Part 2. Wind wave spectra // Nonlinear. Geoph. Processes, Vol. 20, P. 841-856, 2013.

  10. Controlling Air Traffic (Simulated) in the Presence of Automation (CATS PAu) 1995: A Study of Measurement Techniques for Situation Awareness in Air Traffic Control

    NASA Technical Reports Server (NTRS)

    French, Jennifer R.

    1995-01-01

    As automated systems proliferate in aviation systems, human operators are taking on less and less of an active role in the jobs they once performed, often reducing what should be important jobs to tasks barely more complex than monitoring machines. When operators are forced into these roles, they risk slipping into hazardous states of awareness, which can lead to reduced skills, lack of vigilance, and the inability to react quickly and competently when there is a machine failure. Using Air Traffic Control (ATC) as a model, the present study developed tools for conducting tests focusing on levels of automation as they relate to situation awareness. Subjects participated in a two-and-a-half hour experiment that consisted of a training period followed by a simulation of air traffic control similar to the system presently used by the FAA, then an additional simulation employing automated assistance. Through an iterative design process utilizing numerous revisions and three experimental sessions, several measures for situational awareness in a simulated Air Traffic Control System were developed and are prepared for use in future experiments.

  11. The effect of different inlet conditions of air in a rectangular channel on convection heat transfer: Turbulence flow

    SciTech Connect

    Kurtbas, Irfan

    2008-10-15

    Theoretical and empirical correlations for duct flow are given for hydrodynamically and thermally developed flow in most of previous studies. However, this is commonly not a realistic inlet configuration for heat exchanger, in which coolant flow generally turns through a serpentine shaped passage before entering heat sinks. Accordingly, an experimental investigation was carried out to determine average heat transfer coefficients in uniformly heated rectangular channel with 45 and 90 turned flow, and with wall mounted a baffle. The channel was heated through bottom side with the baffle. In present work, a detailed study was conducted for three different height of entry channel (named as the ratio of the height of entry channel to the height of test section (anti H{sub c}=h{sub c}/H)) by varying Reynolds number (Re{sub Dh}). Another variable parameter was the ratio of the baffle height to the channel height (anti H{sub b}=h{sub b}/H). Only one baffle was attached on the bottom (heating) surface. The experimental procedure was validated by comparing the data for the straight channel with no baffle. Reynolds number (Re{sub Dh}) was varied from 2800 to 30,000, so the flow was considered as only turbulent regime. All experiments were conduced with air accordingly; Prandtl number (Pr) was approximately fixed at 0.71. The results showed that average Nusselt number for {theta}=45 and {theta}=90 were 9% and 30% higher, respectively, than that of the straight channel without baffle. Likewise, the pressure drop increased up to 4.4 to 5.3 times compare to the straight channel. (author)

  12. Aircraft Dynamic Modeling in Turbulence

    NASA Technical Reports Server (NTRS)

    Morelli, Eugene A.; Cunninham, Kevin

    2012-01-01

    A method for accurately identifying aircraft dynamic models in turbulence was developed and demonstrated. The method uses orthogonal optimized multisine excitation inputs and an analytic method for enhancing signal-to-noise ratio for dynamic modeling in turbulence. A turbulence metric was developed to accurately characterize the turbulence level using flight measurements. The modeling technique was demonstrated in simulation, then applied to a subscale twin-engine jet transport aircraft in flight. Comparisons of modeling results obtained in turbulent air to results obtained in smooth air were used to demonstrate the effectiveness of the approach.

  13. The study of the effect of the surface wave on turbulent stably-stratified boundary layer air-flow by direct numerical simulation

    NASA Astrophysics Data System (ADS)

    Druzhinin, Oleg; Troitskaya, Yliya; Zilitinkevich, Sergej

    2015-04-01

    Detailed knowledge of the interaction of surface water waves with the wind flow is of primary importance for correct parameterization of turbulent momentum and heat fluxes which define the energy and momentum transfer between the atmosphere and hydrosphere. The objective of the present study is to investigate the properties of the stably stratified turbulent boundary-layer (BL) air-flow over waved water surface by direct numerical simulation (DNS) at a bulk Reynolds number varying from 15000 to 80000 and the surface-wave slope up to ka = 0.2. The DNS results show that the BL-flow remains in the statistically stationary, turbulent regime if the Reynolds number (ReL) based on the Obukhov length scale and friction velocity is sufficiently large (ReL > 100). In this case, mean velocity and temperature vertical profiles are well predicted by log-linear asymptotic solutions following from the Monin-Obukhov similarity theory provided the velocity and temperature roughness parameters, z0U and z0T, are appropriately prescribed. Both z0U and z0T increase for larger surface-wave slope. DNS results also show that turbulent momentum and heat fluxes and turbulent velocity and temperature fluctuations are increased for larger wave slope (ka) whereas the mean velocity and temperature derivatives remain practically the same for different ka. Thus, we conclude that the source of turbulence enhancement in BL-flow are perturbations induced by the surface wave, and not the shear instability of the bulk flow. On the other hand, if stratification is sufficiently strong, and the surface-wave slope is sufficiently small, the BL-flow over waved surface relaminarizes in the bulk of the domain. However, if the surface-wave slope exceeds a threshold value, the velocity and temperature fluctuations remain finite in the vicinity of the critical-layer level, where the surface-wave phase velocity coincides with the mean flow velocity. We call this new stably-stratified BL-flow regime observed in

  14. CAT-generating mechanisms

    NASA Technical Reports Server (NTRS)

    Wurtele, Morton G.

    1987-01-01

    The development of instability configurations; the transition from unstable growth of these configurations into turbulence; a description of the nature of that turbulence; the question of decay of turbulence; and the existence of what is called fossil turbulence are discussed.

  15. Cat scratch disease

    MedlinePlus

    ... t scratch and bite. Don't allow a cat to lick your skin, eyes, mouth, or open wounds or scratches. Use flea control measures to lower the risk your cat develops the disease. Don't touch feral cats. ...

  16. Analysis of the Chemically-Reactive Mixing Region Between a Turbulent Rocket Exhaust and a Confined Air Stream

    DTIC Science & Technology

    1965-03-03

    experimental results of Zakkay, et al , (HO it was concluded that the turbulent Schmidt and Lewis numbers ranged from 0.3 to 2.3 and 0.U to 1.0...The experimental investigation of Zakkay, et al ., was conducted to determine the turbulent mixing of coaxial Jets for both subsonic and supersonic flow...CO, G02, N2, HC1, Al , Al ^, and one additional inert species which remained as an inpuE" selection^ The phenomenological model employed for the

  17. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  18. Calculation of Turbulent Expansion Processes

    NASA Technical Reports Server (NTRS)

    Tollmien, Walter

    1945-01-01

    On the basis of certain formulas recently established by L. Prandtl for the turbulent interchange of momentum in stationary flows, various cases of "free turbulence" - that is, of flows without boundary walls - are treated in the present report. Prandtl puts the apparent shearing stress introduced by the turbulent momentum interchange. This present report deals first with the mixing of an air stream of uniform velocity with the adjacent still air, than with the expansion or diffusion of an air jet in the surrounding air space.

  19. Modeling and Simulation of Turbulent Flows through a Solar Air Heater Having Square-Sectioned Transverse Rib Roughness on the Absorber Plate

    PubMed Central

    Yadav, Anil Singh; Bhagoria, J. L.

    2013-01-01

    Solar air heater is a type of heat exchanger which transforms solar radiation into heat energy. The thermal performance of conventional solar air heater has been found to be poor because of the low convective heat transfer coefficient from the absorber plate to the air. Use of artificial roughness on a surface is an effective technique to enhance the rate of heat transfer. A CFD-based investigation of turbulent flow through a solar air heater roughened with square-sectioned transverse rib roughness has been performed. Three different values of rib-pitch (P) and rib-height (e) have been taken such that the relative roughness pitch (P/e = 14.29) remains constant. The relative roughness height, e/D, varies from 0.021 to 0.06, and the Reynolds number, Re, varies from 3800 to 18,000. The results predicted by CFD show that the average heat transfer, average flow friction, and thermohydraulic performance parameter are strongly dependent on the relative roughness height. A maximum value of thermohydraulic performance parameter has been found to be 1.8 for the range of parameters investigated. Comparisons with previously published work have been performed and found to be in excellent agreement. PMID:24222752

  20. A new framework for estimation and comparative assessment of air-sea turbulent fluxes in reanalyses and climate models

    NASA Astrophysics Data System (ADS)

    Gulev, Sergey; Tilinina, Natalia; Belyaev, Konstantin

    2013-04-01

    Reanalyses fluxes and flux-related variables at high temporal resolution are widely used forcing ocean general circulation models, for the case studies and estimation of regional energy budgets. In order to evaluate surface fluxes in modern era reanalyses and climate models we suggest a new approach based on two parametric modified Fisher-Tippett (MFT) distribution applied to turbulent heat fluxes. Two comparisons were performed - using direct surface turbulent flux output from different products (NCEP, NCEP-DOE, NCEP-CFSR, MERRA, JRA-25, ERA-Interim) and applying a single parameterization (COARE-3) to the reanalysis state variables. These allow for distinguishing between the impact of reanalysis surface parameterizations and variables onto surface turbulent fluxes. Statistical properties of surface turbulent fluxes were intercompared in terms of the distribution parameters (scale and location) and extreme fluxes derived from distribution tails. In all reanalyses extreme turbulent heat fluxes amount to 1500-2000 W/m2 (for the 99th percentile) and can exceed 2000 W/m2 for higher percentiles in the western boundary current extension (WBCE) regions. Different reanalyses show significantly different shape of MFT distribution, implying considerable differences in the estimates of extreme fluxes. The highest extreme turbulent latent heat fluxes are diagnosed in NCEP-DOE, ERA-Interim and NCEP-CFSR reanalyses with the smallest being in MERRA. These differences may not necessarily reflect the differences in mean values. Analysis show that differences in statistical properties of the state variables are the major source of differences in the shape of PDF and estimates of extreme fluxes while the contribution of computational schemes used in different reanalyses is minor. The strongest differences in the characteristics of probability distributions of surface fluxes between different reanalyses is found in the Southern Ocean. Importantly, climate models, being capable of

  1. Characterizing glottal jet turbulence.

    PubMed

    Alipour, Fariborz; Scherer, Ronald C

    2006-02-01

    Air pressure associated with airflow from the lungs drives the vocal folds into oscillation and allows the air to exit the glottis as a turbulent jet, even though laminar flow may enter the glottis from the trachea. The separation of the turbulence from the deterministic portion of the glottal jet was investigated in the excised canine larynx model. The present study is methodological in that the main goal was to examine three methods of obtaining reasonable representations of both the deterministic signal and the residual turbulence portion: (a) smoothing, (b) wavelet denoising, and (c) ensemble averaging. Ensemble averaging resulted in a deterministic signal that disregarded gross cyclic alterations while exaggerating the turbulence intensity. Wavelet denoising can perform an excellent analysis and synthesis of the glottal velocity, but was problematic in determining which levels of analysis to choose to represent both the deterministic and turbulence appropriately. Smoothing appeared to be the most appropriate for phonation velocities because it preserved gross cyclic variations important to perturbations and modulations, while extracting turbulence at what appears to be reasonable levels.

  2. Cat Scratch Disease

    MedlinePlus

    Cat scratch disease (CSD) is an illness caused by the bacterium Bartonella henselae. Almost half of all cats carry the infection ... symptoms of CSD, call your doctor. Centers for Disease Control and Prevention

  3. Cat-Scratch Disease

    MedlinePlus

    ... Patients Infants and Young Children Publications & Materials Announcements Cat-Scratch Disease Recommend on Facebook Tweet Share Compartir ( ... play and learn how to attack prey. How cats and people become infected Kitten playing with a ...

  4. Evolution of the air/SF6 turbulent mixing zone for different lengths of SF6: shock tube visualizations and 3D simulations

    NASA Astrophysics Data System (ADS)

    Haas, Jean-Francois; Griffond, Jerome; Souffland, Denis; Bouzgarrou, Ghazi; Bury, Yannick; Jamme, Stephane

    2015-11-01

    A turbulent mixing zone (TMZ) is created in a vertical shock tube (based in ISAE DAEP) when a Mach 1.2 shock wave in air accelerates impulsively to 70 m/s an air/SF6 interface. The gases are initially separated by a thin nitrocellulose membrane maintained flat and parallel to the shock by two wire grids. The upper grid (SF6 side) of square mesh spacing hu 1.8 or 12.1 mm is expected to seed perturbation for the Richtmyer-Meshkov instability (RMI) while the lower grid with hl 1 mm is needed to prevent the membrane from bulging prior to the shot. The experiments were carried out for different lengths L of SF6 between the initial interface and the shock tube's end plate: 10, 15, 20, 25 and 30 cm. The time resolved Schlieren image processing based on space and frequency filtering yields similar evolution for the TMZ thickness. Before reshock, the thickness grows initially fast then slows down and reaches different values (10 to 14 mm) according to L. Soon after reshock, the TMZ thickness growths rate is 21 mm/ms independently of L and hu. Numerical Schlieren images generated from 3D numerical simulations (performed at CEA DAM IDF) are analyzed as the experimental ones for L 15 and 25 cm and for hu 1.8 and 12.1 mm. The very weak experimental dependence on hu is not obtained by simulation as expected from dimensional reasoning. This discrepancy remains paradoxical.

  5. Cat-Scratch Disease

    MedlinePlus

    ... have diabetes or those who have acquired immunodeficiency syndrome (AIDS).Cat-scratch disease is also called cat-scratch fever. ... You can also get the bacteria in your eyes if you pet a cat that has the bacteria on its fur and ...

  6. CATS Featured Articles

    Atmospheric Science Data Center

    2017-01-31

      CATS Featured Articles       A Slice of Cirrus: Image of ... just hours before by the Cloud-Aerosol Transport System (CATS) onboard the International Space Station. Nighttime View of Raung Volcanic Plume : Natural Hazards  - The CATS instrument slices through darkness to reveal the vertical structure of a ...

  7. Turbulence forecasting

    NASA Technical Reports Server (NTRS)

    Chandler, C. L.

    1987-01-01

    In order to forecast turbulence, one needs to have an understanding of the cause of turbulence. Therefore, an attempt is made to show the atmospheric structure that often results when aircraft encounter moderate or greater turbulence. The analysis is based on thousands of hours of observations of flights over the past 39 years of aviation meteorology.

  8. The Turbulent Boundary Layer Near the Air-Water Interface on a Surface-Piercing Flat Plate

    NASA Astrophysics Data System (ADS)

    Washuta, Nathan; Masnadi, Naeem; Duncan, James H.

    2015-11-01

    Turbulent fluctuations in the vicinity of the water free surface along a flat, vertically oriented surface-piercing plate are studied experimentally using a laboratory-scale experiment. In this experiment, a meter-wide stainless steel belt travels horizontally in a loop around two rollers with vertically oriented axes, which are separated by 7.5 meters. This belt device is mounted inside a large water tank with the water level set just below the top edge of the belt. The belt, rollers, and supporting frame are contained within a sheet metal box to keep the device dry except for one 6-meter-long straight test section between rollers. The belt is launched from rest with a 3- g acceleration in order to quickly reach steady state velocity. This creates a temporally evolving boundary layer analogous to the spatially evolving boundary layer created along a flat-sided ship moving at the same velocity, with a length equivalent to the length of belt that has passed the measurement region since the belt motion began. Cinematic Stereo PIV measurements are performed in planes parallel to the free surface by imaging the flow from underneath the tank in order to study the modification of the boundary layer flow field due to the effects of the water free surface. The support of the Office of Naval Research under grant N000141110029 is gratefully acknowledged.

  9. Transfer function characteristics of bluff-body stabilized, conical V-shaped premixed turbulent propane-air flames

    SciTech Connect

    Chaparro, Andres; Landry, Eric; Cetegen, Baki M.

    2006-04-15

    The response of bluff-body stabilized conical V-shaped premixed flames to periodic upstream velocity oscillations was characterized as a function of oscillation frequency, mean flow velocity, and equivalence ratio. The flame heat release response to the imposed velocity oscillations was determined from the CH* chemiluminescence captured by two photomultiplier (PMT) detectors at a wavelength of 430 nm. One of the PMTs viewed flame radiation in a 10-mm horizontal slice, 50 mm above the bluff-body. The second PMT observed the overall flame radiation. The flame transfer function characteristics were determined from the spectral analysis of the velocity and PMT signals. It was found that the flame heat release amplitude response is confined to low-frequency excitation below a Strouhal number of 4. The phase relationship of the transfer function for these turbulent flames was evaluated using the signal from the spatially masked PMT. The transfer function estimate based on these data exhibits second-order characteristics with a phase lag between the velocity and heat release signals. The localized heat-release response contains frequencies that are multiples of the excitation frequency, suggesting splitting and tilting of flame structures as well as some nonlinear effects. Increase of flame equivalence ratio from lean toward stoichiometric resulted in slight amplification of the high-frequency response. (author)

  10. Combined effect of grid turbulence and unsteady wake on film effectiveness and heat transfer coefficient of a gas turbine blade with air and CO{sub 2} film injection

    SciTech Connect

    Ekkad, S.V.; Mehendale, A.B.; Han, J.C.; Lee, C.P.

    1997-07-01

    Experiments were performed to study the combined effect of grid turbulence and unsteady wake on film effectiveness and heat transfer coefficient of a turbine blade model. Tests were done on a five-blade linear cascade at the chord Reynolds number of 3.0 {times} 10{sup 5} at cascade inlet. Several combinations of turbulence grids, their locations, and unsteady wake strengths were used to generate various upstream turbulence conditions. The test blade had three rows of film holes in the leading edge region and two rows each on the pressure and suction surfaces. Air and CO{sub 2} were used as injectants. Results show that Nusselt numbers for a blade with film injection are much higher than that without film holes. An increase in mainstream turbulence level causes an increase in Nusselt numbers and a decrease in film effectiveness over most of the blade surface, for both density injectants, and at all blowing ratios. A free-stream turbulence superimposed on an unsteady wake significantly affects Nusselt numbers and film effectiveness compared with only an unsteady wake condition.

  11. Prediction of hydrodynamics and chemistry of confined turbulent methane-air flames with attention to formation of oxides of nitrogen

    NASA Technical Reports Server (NTRS)

    Elghobashi, S.; Spalding, D. B.; Srivatsa, S. K.

    1977-01-01

    A formulation of the governing partial differential equations for fluid flow and reacting chemical species in a tubular combustor is presented. A numerical procedure for the solution of the governing differential equations is described, and models for chemical equilibrium and chemical kinetics calculations are presented. The chemical equilibrium model is used to characterize the hydrocarbon reactions. The chemical kinetics model is used to predict the concentrations of the oxides of nitrogen. The combustor consists of a cylindrical duct of varying cross sections with concentric streams of gaseous fuel and air entering the duct at one end. Four sample cases with specified inlet and boundary conditions are considered, and the results are discussed

  12. Turbulent Navier-Stokes Flow Analysis of an Advanced Semispan Diamond-Wing Model in Tunnel and Free Air at High-Lift Conditions

    NASA Technical Reports Server (NTRS)

    Ghaffari, Farhad; Biedron, Robert T.; Luckring, James M.

    2002-01-01

    Turbulent Navier-Stokes computational results are presented for an advanced diamond wing semispan model at low-speed, high-lift conditions. The numerical results are obtained in support of a wind-tunnel test that was conducted in the National Transonic Facility at the NASA Langley Research Center. The model incorporated a generic fuselage and was mounted on the tunnel sidewall using a constant-width non-metric standoff. The computations were performed at to a nominal approach and landing flow conditions.The computed high-lift flow characteristics for the model in both the tunnel and in free-air environment are presented. The computed wing pressure distributions agreed well with the measured data and they both indicated a small effect due to the tunnel wall interference effects. However, the wall interference effects were found to be relatively more pronounced in the measured and the computed lift, drag and pitching moment. Although the magnitudes of the computed forces and moment were slightly off compared to the measured data, the increments due the wall interference effects were predicted reasonably well. The numerical results are also presented on the combined effects of the tunnel sidewall boundary layer and the standoff geometry on the fuselage forebody pressure distributions and the resulting impact on the configuration longitudinal aerodynamic characteristics.

  13. Cat scratch encephalopathy.

    PubMed

    Silver, B E; Bean, C S

    1991-06-01

    Cat scratch disease is usually benign, self-limited and without sequelae. Margileth has established four clinical criteria, three of which must be satisfied to make the diagnosis: 1) a history of animal exposure, usually kitten, with primary skin or ocular lesions; 2) regional chronic adenopathy without other apparent cause; 3) a positive cat scratch disease antigen skin test; and 4) lymph node biopsy demonstrating noncaseating granulomas and germinal center hyperplasia. Central nervous system involvement in cat scratch disease has been previously reported, although it is extremely uncommon. In a several-month period, we encountered two cases of cat scratch disease complicated by encephalopathy. The intents of this paper are twofold: 1) to briefly review the current literature on cat scratch disease, 2) to demonstrate that cat scratch disease complicated by encephalopathy presents acutely with seizures, posturing and coma and resolves rapidly with supportive care.

  14. Computerised Axial Tomography (CAT)

    DTIC Science & Technology

    1990-06-01

    OF COMPUTERISED AXIAL TOMOGRAPHY Paragraph 1.1 ORIGIN, DEVELOPMENT AND MARKET OF CAT Paragraph 1.2 EQUIPMENT Chapter 2 OPERATIONAL PRINCIPLE OF A CT...DEVELOPMENT OF THE COMPUTERISED AXIAL TOMOGRAPHY 1.1 Origin, development and marketing of the CAT The origin of the CAT goes back to 1961 when...count on wide commercial possibilities, in the international market . In particular, EMI entered, very forcefully, the American market , always

  15. Cat-scratch Disease.

    PubMed

    Klotz, Stephen A; Ianas, Voichita; Elliott, Sean P

    2011-01-15

    Cat-scratch disease is a common infection that usually presents as tender lymphadenopathy. It should be included in the differential diagnosis of fever of unknown origin and any lymphadenopathy syndrome. Asymptomatic, bacteremic cats with Bartonella henselae in their saliva serve as vectors by biting and clawing the skin. Cat fleas are responsible for horizontal transmission of the disease from cat to cat, and on occasion, arthropod vectors (fleas or ticks) may transmit the disease to humans. Cat-scratch disease is commonly diagnosed in children, but adults can present with it as well. The causative microorganism, B. henselae, is difficult to culture. Diagnosis is most often arrived at by obtaining a history of exposure to cats and a serologic test with high titers (greater than 1:256) of immunoglobulin G antibody to B. henselae. Most cases of cat-scratch disease are self-limited and do not require antibiotic treatment. If an antibiotic is chosen, azithromycin has been shown in one small study to speed recovery. Infrequently, cat-scratch disease may present in a more disseminated form with hepatosplenomegaly or meningoencephalitis, or with bacillary angiomatosis in patients with AIDS.

  16. Prediction of hydrodynamics and chemistry of confined turbulent methane-air frames in a two concentric tube combustor

    NASA Technical Reports Server (NTRS)

    Markatos, N. C.; Spalding, D. B.; Srivatsa, S. K.

    1978-01-01

    A formulation of the governing partial differential equations for fluid flow and reacting chemical species in a two-concentric-tube combustor is presented. A numerical procedure for the solution of the governing differential equations is described and models for chemical-equilibrium and chemical-kinetics calculations are presented. The chemical-equilibrium model is used to characterize the hydrocarbon reactions. The chemical-kinetics model is used to predict the concentrations of the oxides of nitrogen. The combustor considered consists of two coaxial ducts. Concentric streams of gaseous fuel and air enter the inlet duct at one end; the flow then reverses and flows out through the outer duct. Two sample cases with specified inlet and boundary conditions are considered and the results are discussed.

  17. Turbulence in Natural Environments

    NASA Astrophysics Data System (ADS)

    Banerjee, Tirtha

    Problems in the area of land/biosphere-atmosphere interaction, hydrology, climate modeling etc. can be systematically organized as a study of turbulent flow in presence of boundary conditions in an increasing order of complexity. The present work is an attempt to study a few subsets of this general problem of turbulence in natural environments- in the context of neutral and thermally stratified atmospheric surface layer, the presence of a heterogeneous vegetation canopy and the interaction between air flow and a static water body in presence of flexible protruding vegetation. The main issue addressed in the context of turbulence in the atmospheric surface layer is whether it is possible to describe the macro-states of turbulence such as mean velocity and turbulent velocity variance in terms of the micro-states of the turbulent flow, i.e., a distribution of turbulent kinetic energy across a multitude of scales. This has been achieved by a `spectral budget approach' which is extended for thermal stratification scenarios as well, in the process unifying the seemingly different and unrelated theories of turbulence such as Kolmogorov's hypothesis, Heisenberg's eddy viscosity, Monin Obukhov Similarity Theory (MOST) etc. under a common framework. In the case of a more complex scenario such as presence of a vegetation canopy with edges and gaps, the question that is addressed is in what detail the turbulence is needed to be resolved in order to capture the bulk flow features such as recirculation patterns. This issue is addressed by a simple numerical framework and it has been found out that an explicit prescription of turbulence is not necessary in presence of heterogeneities such as edges and gaps where the interplay between advection, pressure gradients and drag forces are sufficient to capture the first order dynamics. This result can be very important for eddy-covariance flux calibration strategies in non-ideal environments and the developed numerical model can be

  18. Cause of heart murmurs in 57 apparently healthy cats.

    PubMed

    Dirven, M J M; Cornelissen, J M M; Barendse, M A M; van Mook, M C; Sterenborg, J A E M

    2010-11-15

    Heart murmurs are caused by turbulent blood flow or by vibration of cardiac structures. Turbulent blood flow may originate from structural heart disease or from physiological phenomena. The aims of this study were to establish the cause of heart murmurs in apparently healthy adult cats and to determine whether a heart murmur is a reliable indicator of heart disease. In this retrospective study, we reviewed the medical records of cats in which a heart murmur was detected during physical examination by one of the authors in the period January 2008 to December 2009. Cats younger than 6 months and those with systemic disease were excluded. Timing, grade, and point of maximum intensity of the murmur were determined by one observer (MD) before 2D-, M-mode and Doppler echocardiography. Fifty-seven cats (median age 76 months, range 6-194) were included, 30 neutered females and 27 neutered males. All murmurs were systolic and varied in intensity from 2/6 to 5/6. The point of maximum intensity was the left or right parasternal region in 34/57 (61%) of murmurs. Murmurs were caused by dynamic left ventricular outflow tract obstruction in 25/57 (44%) cats, dynamic right ventricular outflow tract obstruction in 9/57 (16%) cats, and combined dynamic left and right outflow tract obstruction in 11/57 (19%) cats. In 5 (9%) cats the cause of the murmur could not be identified. Heart disease was present in 50 (88%) cats, namely, left ventricular hypertrophy in 44 (77%) and congenital defects in 6 (11%) cats. In conclusion, most heart murmurs in apparently healthy cats are detected in the left or right parasternal region and are caused by dynamic left and right ventricular outflow tract obstruction. Because most cats (88%) with a heart murmur had heart disease in this study, if a heart murmur is detected in an apparently healthy cat, echocardiography is recommended to determine the cause of the heart murmur and the presence of heart disease.

  19. Containerless Ripple Turbulence

    NASA Technical Reports Server (NTRS)

    Putterman, Seth; Wright, William; Duval, Walter; Panzarella, Charles

    2002-01-01

    interaction. Furthermore, the steady state distribution of energy again follows a Kolmogorov scaling law; in this case the ripple energy is distributed according to 1/k (sup 7/4). Again, in parallel with vortex turbulence ripple turbulence exhibits intermittency. The problem of ripple turbulence presents an experimental opportunity to generate data in a controlled, benchmarked system. In particular the surface of a sphere is an ideal environment to study ripple turbulence. Waves run around the sphere and interact with each other, and the effect of walls is eliminated. In microgravity this state can be realized for over 2 decades of frequency. Wave turbulence is a physically relevant problem in its own right. It has been studied on the surface of liquid hydrogen and its application to Alfven waves in space is a source of debate. Of course, application of wave turbulence perspectives to ocean waves has been a major success. The experiment which we plan to run in microgravity is conceptually straightforward. Ripples are excited on the surface of a spherical drop of fluid and then their amplitude is recorded with appropriate photography. A key challenge is posed by the need to stably position a 10cm diameter sphere of water in microgravity. Two methods are being developed. Orbitec is using controlled puffs of air from at least 6 independent directions to provided the positioning force. This approach has actually succeeded to position and stabilize a 4cm sphere during a KC 135 segment. Guigne International is using the radiation pressure of high frequency sound. These transducers have been organized into a device in the shape of a dodecahedron. This apparatus 'SPACE DRUMS' has already been approved for use for combustion synthesis experiments on the International Space Station. A key opportunity presented by the ripple turbulence data is its use in driving the development of codes to simulate its properties.

  20. Containerless Ripple Turbulence

    NASA Astrophysics Data System (ADS)

    Putterman, Seth; Wright, William; Duval, Walter; Panzarella, Charles

    2002-11-01

    interaction. Furthermore, the steady state distribution of energy again follows a Kolmogorov scaling law; in this case the ripple energy is distributed according to 1/k 7/4. Again, in parallel with vortex turbulence ripple turbulence exhibits intermittency. The problem of ripple turbulence presents an experimental opportunity to generate data in a controlled, benchmarked system. In particular the surface of a sphere is an ideal environment to study ripple turbulence. Waves run around the sphere and interact with each other, and the effect of walls is eliminated. In microgravity this state can be realized for over 2 decades of frequency. Wave turbulence is a physically relevant problem in its own right. It has been studied on the surface of liquid hydrogen and its application to Alfven waves in space is a source of debate. Of course, application of wave turbulence perspectives to ocean waves has been a major success. The experiment which we plan to run in microgravity is conceptually straightforward. Ripples are excited on the surface of a spherical drop of fluid and then their amplitude is recorded with appropriate photography. A key challenge is posed by the need to stably position a 10cm diameter sphere of water in microgravity. Two methods are being developed. Orbitec is using controlled puffs of air from at least 6 independent directions to provided the positioning force. This approach has actually succeeded to position and stabilize a 4cm sphere during a KC 135 segment. Guigne International is using the radiation pressure of high frequency sound. These transducers have been organized into a device in the shape of a dodecahedron. This apparatus 'SPACE DRUMS' has already been approved for use for combustion synthesis experiments on the International Space Station. A key opportunity presented by the ripple turbulence data is its use in driving the development of codes to simulate its properties.

  1. That Fat Cat

    ERIC Educational Resources Information Center

    Lambert, Phyllis Gilchrist

    2012-01-01

    This activity began with a picture book, Nurit Karlin's "Fat Cat On a Mat" (HarperCollins; 1998). The author and her students started their project with a 5-inch circular template for the head of their cats. They reviewed shapes as they drew the head and then added the ears and nose, which were triangles. Details to the face were added when…

  2. State of cat genomics.

    PubMed

    O'Brien, Stephen J; Johnson, Warren; Driscoll, Carlos; Pontius, Joan; Pecon-Slattery, Jill; Menotti-Raymond, Marilyn

    2008-06-01

    Our knowledge of cat family biology was recently expanded to include a genomics perspective with the completion of a draft whole genome sequence of an Abyssinian cat. The utility of the new genome information has been demonstrated by applications ranging from disease gene discovery and comparative genomics to species conservation. Patterns of genomic organization among cats and inbred domestic cat breeds have illuminated our view of domestication, revealing linkage disequilibrium tracks consequent of breed formation, defining chromosome exchanges that punctuated major lineages of mammals and suggesting ancestral continental migration events that led to 37 modern species of Felidae. We review these recent advances here. As the genome resources develop, the cat is poised to make a major contribution to many areas in genetics and biology.

  3. Comparative study of aural microflora in healthy cats, allergic cats and cats with systemic disease.

    PubMed

    Pressanti, Charline; Drouet, Clémence; Cadiergues, Marie-Christine

    2014-12-01

    Twenty healthy cats (group 1) with clinically normal ears, 15 cats with systemic disease (group 2) and 15 allergic cats (group 3) were included in a prospective study. The experimental unit was the ear. A clinical score was established for each ear canal after otoscopic examination. Microbial population was assessed on cytological examination of smears performed with the cotton-tipped applicator smear technique. Fungal population was significantly more prominent in allergic cats (P <0.001) and in diseased cats compared with healthy cats (P <0.02). Bacterial population was significantly higher in allergic cats than in healthy cats (P <0.001) and cats suffering from systemic disease (P <0.001). Bacterial overgrowth was also higher in cats with systemic disease than healthy cats. In cats from group 2, only fungal overgrowth was associated with otitis severity. In group 3, only bacterial overgrowth was associated with otitis severity.

  4. Atmospheric Turbulence Research at DFVLR

    DTIC Science & Technology

    1988-07-01

    the chairmanship of Dr G.Coupry. Ce rapport fournit une synthese des travaux effecues au DFVLR sur Ia turbulence atmospherique , avec une description des...Turbulent trarsport in the convective bundary layer. Proc. EUPASAP Sympos. on Aircraft Measurements in Relation to Air pollution , Garmscd, -.- 9. Sept...convective boundayr layer structure for usne in pollution dispersion model . J. Climate App1. Meteorol., 25, 1609-1624. Wygaard. J.C., 1986-: Measrment

  5. Quantum Turbulence

    NASA Astrophysics Data System (ADS)

    Tsubota, Makoto

    2008-11-01

    The present article reviews the recent developments in the physics of quantum turbulence. Quantum turbulence (QT) was discovered in superfluid 4He in the 1950s, and the research has tended toward a new direction since the mid 90s. The similarities and differences between quantum and classical turbulence have become an important area of research. QT is comprised of quantized vortices that are definite topological defects, being expected to yield a model of turbulence that is much simpler than the classical model. The general introduction of the issue and a brief review on classical turbulence are followed by a description of the dynamics of quantized vortices. Then, we discuss the energy spectrum of QT at very low temperatures. At low wavenumbers, the energy is transferred through the Richardson cascade of quantized vortices, and the spectrum obeys the Kolmogorov law, which is the most important statistical law in turbulence; this classical region shows the similarity to conventional turbulence. At higher wavenumbers, the energy is transferred by the Kelvin-wave cascade on each vortex. This quantum regime depends strongly on the nature of each quantized vortex. The possible dissipation mechanism is discussed. Finally, important new experimental studies, which include investigations into temperature-dependent transition to QT, dissipation at very low temperatures, QT created by vibrating structures, and visualization of QT, are reviewed. The present article concludes with a brief look at QT in atomic Bose-Einstein condensates.

  6. Giardia infection in cats.

    PubMed

    Janeczko, Stephanie; Griffin, Brenda

    2010-08-01

    The protozoon Giardia duodenalis is a common gastrointestinal parasite of cats. While most Giardia-infected cats are asymptomatic, acute small bowel diarrhea, occasionally with concomitant weight loss, may occur. Giardia poses a diagnostic challenge, but newer tests, including a commercially available ELISA kit, have improved clinicians' ability to obtain an accurate diagnosis. Several treatment options have been reported, and although none has been shown to be universally effective, most cases can be successfully managed with drug therapy, supportive measures, and environmental control. Current recommendations suggest that combination therapy with fenbendazole and metronidazole may be the safest, most effective treatment option for symptomatic cats.

  7. Cat tongue Velcro

    NASA Astrophysics Data System (ADS)

    Noel, Alexis; Martinez, Andrea; Jung, Hyewon; Tsai, Ting-Wen; Hu, David

    2016-11-01

    A cat's tongue is covered in an array of spines called papillae. These spines are thought to be used in grooming and rasping meat from bones of prey, although no mechanism has been given. We use high-speed video to film a cat removing cat food deeply wedged into a 3-D printed fur mat. We show that the spines on the tongue act as Velcro for particles. The tongue itself is highly elastic. As the cat presses it against a substrate, the tongue flattens and the spines separate. When the tongue is removed from the substrate the spines come together, wedging particles between them. This elasticity-driven entrapment permits the surface of the tongue to act as a carrier for hard to reach particles, and to increase the efficacy of grooming and feeding.

  8. Wall Turbulence.

    ERIC Educational Resources Information Center

    Hanratty, Thomas J.

    1980-01-01

    This paper gives an account of research on the structure of turbulence close to a solid boundary. Included is a method to study the flow close to the wall of a pipe without interferring with it. (Author/JN)

  9. Wave turbulence

    NASA Astrophysics Data System (ADS)

    Nazarenko, Sergey

    2015-07-01

    Wave turbulence is the statistical mechanics of random waves with a broadband spectrum interacting via non-linearity. To understand its difference from non-random well-tuned coherent waves, one could compare the sound of thunder to a piece of classical music. Wave turbulence is surprisingly common and important in a great variety of physical settings, starting with the most familiar ocean waves to waves at quantum scales or to much longer waves in astrophysics. We will provide a basic overview of the wave turbulence ideas, approaches and main results emphasising the physics of the phenomena and using qualitative descriptions avoiding, whenever possible, involved mathematical derivations. In particular, dimensional analysis will be used for obtaining the key scaling solutions in wave turbulence - Kolmogorov-Zakharov (KZ) spectra.

  10. Fatal big cat attacks.

    PubMed

    Cohle, S D; Harlan, C W; Harlan, G

    1990-09-01

    Two cases of fatal attacks by large cats are presented. In the first case, a 30-year-old female zoo worker was attacked by a jaguar that had escaped its cage. In the second case, a 2-year-old girl was fatally injured by her father's pet leopard. The pattern of injuries in these cases is nearly identical to those of these cats' prey in the wild.

  11. Control of the Periodic Turbulent Flow over a Semicircular Airfoil with the Use of the Slot Suction of the Air from a Circular Vortex Cell at Small Angles of Attack

    NASA Astrophysics Data System (ADS)

    Isaev, S. I.; Baranov, P. A.; Sudakov, A. G.; Usachev, A. E.

    2016-11-01

    It is shown that, in the case where, into the back wall of a semicircular airfoil with an angle of attack of 5°, a vortex cell of diameter 0.2 in fractions of the airfoil chord is built in and the mean-mass rate of slot suction of the air from this cell is larger than 0.15 of the incident-flow velocity, the pattern of the turbulent flow over the airfoil is transformed, and, at an optimum suction rate of 0.75, the lift coefficient of the airfoil reaches a maximum value of the order of 1.7 at an aerodynamic efficiency of 10.

  12. Using random forests to diagnose aviation turbulence.

    PubMed

    Williams, John K

    Atmospheric turbulence poses a significant hazard to aviation, with severe encounters costing airlines millions of dollars per year in compensation, aircraft damage, and delays due to required post-event inspections and repairs. Moreover, attempts to avoid turbulent airspace cause flight delays and en route deviations that increase air traffic controller workload, disrupt schedules of air crews and passengers and use extra fuel. For these reasons, the Federal Aviation Administration and the National Aeronautics and Space Administration have funded the development of automated turbulence detection, diagnosis and forecasting products. This paper describes a methodology for fusing data from diverse sources and producing a real-time diagnosis of turbulence associated with thunderstorms, a significant cause of weather delays and turbulence encounters that is not well-addressed by current turbulence forecasts. The data fusion algorithm is trained using a retrospective dataset that includes objective turbulence reports from commercial aircraft and collocated predictor data. It is evaluated on an independent test set using several performance metrics including receiver operating characteristic curves, which are used for FAA turbulence product evaluations prior to their deployment. A prototype implementation fuses data from Doppler radar, geostationary satellites, a lightning detection network and a numerical weather prediction model to produce deterministic and probabilistic turbulence assessments suitable for use by air traffic managers, dispatchers and pilots. The algorithm is scheduled to be operationally implemented at the National Weather Service's Aviation Weather Center in 2014.

  13. Cell volume regulation in the perfused liver of a freshwater air-breathing cat fish Clarias batrachus under aniso-osmotic conditions: roles of inorganic ions and taurine.

    PubMed

    Goswami, Carina; Saha, Nirmalendu

    2006-12-01

    The roles of various inorganic ions and taurine, an organic osmolyte, in cell volume regulation were investigated in the perfused liver of a freshwater air-breathing catfish Clarias batrachus under aniso-osmotic conditions. There was a transient increase and decrease of liver cell volume following hypotonic (-80 mOsmol/l) and hypertonic (+80 mOsmol/l) exposures,respectively, which gradually decreased/increased near to the control level due to release/uptake of water within a period of 25-30 min. Liver volume decrease was accompanied by enhanced efflux of K+ (9.45 +/- 0.54 micromol/g liver) due to activation of Ba(2+)- and quinidine-sensitive K(+) channel, and to a lesser extent due to enhanced efflux of Cl(-) (4.35+/- 0.25 micromol/g liver) and Na+ (3.68+/- 0.37 micromol/g liver). Conversely, upon hypertonic exposure, there was amiloride-and ouabain-sensitive uptake of K+ (9.78+/- 0.65 micromol/g liver), and also Cl(-) (3.72 +/- 0.25 micromol/g liver).The alkalization/acidification of the liver effluents under hypo-/hypertonicity was mainly due to movement of various ions during volume regulatory processes. Taurine,an important organic osmolyte, appears also to play a very important role in hepatocyte cell volume regulation in the walking catfish as evidenced by the fact that hypo- and hyper-osmolarity caused transient efflux (5.68 +/- 0.38 micromol/g liver) and uptake (6.38 +/- 0.45 micromol/g liver) of taurine, respectively. The taurine efflux was sensitive to 4,4' -di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS, an anion channel blocker), but the uptake was insensitive to DIDS, thus indicating that the release and uptake of taurine during volume regulatory processes are unidirectional. Although the liver of walking catfish possesses the RVD and RVI mechanisms, it is to be noted that liver cells remain partly swollen and shrunken during anisotonic exposures,thereby possibly causing various volume-sensitive metabolic changes in the liver as reported earlier.

  14. Premixed autoignition in compressible turbulence

    NASA Astrophysics Data System (ADS)

    Konduri, Aditya; Kolla, Hemanth; Krisman, Alexander; Chen, Jacqueline

    2016-11-01

    Prediction of chemical ignition delay in an autoignition process is critical in combustion systems like compression ignition engines and gas turbines. Often, ignition delay times measured in simple homogeneous experiments or homogeneous calculations are not representative of actual autoignition processes in complex turbulent flows. This is due the presence of turbulent mixing which results in fluctuations in thermodynamic properties as well as chemical composition. In the present study the effect of fluctuations of thermodynamic variables on the ignition delay is quantified with direct numerical simulations of compressible isotropic turbulence. A premixed syngas-air mixture is used to remove the effects of inhomogeneity in the chemical composition. Preliminary results show a significant spatial variation in the ignition delay time. We analyze the topology of autoignition kernels and identify the influence of extreme events resulting from compressibility and intermittency. The dependence of ignition delay time on Reynolds and turbulent Mach numbers is also quantified. Supported by Basic Energy Sciences, Dept of Energy, United States.

  15. Influence of avenue-trees on air quality at the urban neighborhood scale. Part I: quality assurance studies and turbulent Schmidt number analysis for RANS CFD simulations.

    PubMed

    Gromke, Christof; Blocken, Bert

    2015-01-01

    Flow and dispersion of traffic pollutants in a generic urban neighborhood with avenue-trees were investigated with Computational Fluid Dynamics (CFD). In Part I of this two-part contribution, quality assessment and assurance for CFD simulations in urban and vegetation configurations were addressed,before in Part II flow and dispersion in a generic urban neighborhood with multiple layouts of avenue trees were studied. In a first step, a grid sensitivity study was performed that inferred that a cell count of 20 per building height and 12 per canyon width is sufficient for reasonable grid insensitive solutions. Next, the performance of the realizable k-ε turbulence model in simulating urban flows and of the applied vegetation model in simulating flow and turbulence in trees was validated. Finally, based on simulations of street canyons with and without avenue-trees, an appropriate turbulent Schmidt number or modeling dispersion in the urban neighborhood was determined as Sc(t) =0.5.

  16. Soliton turbulence

    NASA Technical Reports Server (NTRS)

    Tchen, C. M.

    1986-01-01

    Theoretical and numerical works in atmospheric turbulence have used the Navier-Stokes fluid equations exclusively for describing large-scale motions. Controversy over the existence of an average temperature gradient for the very large eddies in the atmosphere suggested that a new theoretical basis for describing large-scale turbulence was necessary. A new soliton formalism as a fluid analogue that generalizes the Schrodinger equation and the Zakharov equations has been developed. This formalism, processing all the nonlinearities including those from modulation provided by the density fluctuations and from convection due to the emission of finite sound waves by velocity fluctuations, treats large-scale turbulence as coalescing and colliding solitons. The new soliton system describes large-scale instabilities more explicitly than the Navier-Stokes system because it has a nonlinearity of the gradient type, while the Navier-Stokes has a nonlinearity of the non-gradient type. The forced Schrodinger equation for strong fluctuations describes the micro-hydrodynamical state of soliton turbulence and is valid for large-scale turbulence in fluids and plasmas where internal waves can interact with velocity fluctuations.

  17. Cats protecting birds revisited.

    PubMed

    Fan, Meng; Kuang, Yang; Feng, Zhilan

    2005-09-01

    In this paper, we revisit the dynamical interaction among prey (bird), mesopredator (rat), and superpredator (cat) discussed in [Courchamp, F., Langlais, M., Sugihara, G., 1999. Cats protecting birds: modelling the mesopredator release effect. Journal of Animal Ecology 68, 282-292]. First, we develop a prey-mesopredator-superpredator (i.e., bird-rat-cat, briefly, BRC) model, where the predator's functional responses are derived based on the classical Holling's time budget arguments. Our BRC model overcomes several model construction problems in Courchamp et al. (1999), and admits richer, reasonable and realistic dynamics. We explore the possible control strategies to save or restore the bird by controlling or eliminating the rat or the cat when the bird is endangered. We establish the existence of two types of mesopredator release phenomena: severe mesopredator release, where once superpredators are suppressed, a burst of mesopredators follows which leads their shared prey to extinction; and mild mesopredator release, where the mesopredator release could assert more negative impact on the endemic prey but does not lead the endemic prey to extinction. A sharp sufficient criterion is established for the occurrence of severe mesopredator release. We also show that, in a prey-mesopredator-superpredator trophic food web, eradication of introduced superpredators such as feral domestic cats in the BRC model, is not always the best solution to protect endemic insular prey. The presence of a superpredator may have a beneficial effect in such systems.

  18. Hearing disorders in cats.

    PubMed

    Strain, George M

    2017-03-01

    Practical relevance: Auditory function is a sense that is central to life for cats - being important in situational awareness of potential predators, pursuit of prey, and for communication with conspecifics, humans and other species. Deafness in cats is most frequently the result of a genetic disorder, strongly associated with white fur and blue eyes, but may also result from acquired causes such as advancing age, ototoxic drugs, infection, environmental noise and physical trauma. Deafness can be sensorineural, where there is loss of cochlear hair cells, or conductive, where sound is muffled on its way to the inner ear. Clinical challenges: Establishing whether a cat is deaf can be difficult as behavioral testing of hearing is subjective and does not reliably detect unilateral deafness. Brainstem auditory evoked response testing is an objective measure but is limited in its availability. Currently, sensorineural deafness is irreversible because no treatments are available to restore lost hair cells. Conductive hearing loss can usually be treated, although full hearing recovery following otitis media may take weeks as the body clears the middle ear of debris. Evidence base: The author draws on the published literature and his extensive research on clinical aspects and molecular genetics of deafness, principally in companion animals, to review types and forms of deafness in cats. He also discusses current diagnostic approaches and provides brief advice for managing cats with hearing loss.

  19. The Feline Mystique: Dispelling the Myth of the Independent Cat.

    ERIC Educational Resources Information Center

    Soltow, Willow

    1984-01-01

    Describes learning activities about cats for primary and intermediate grades. Primary grade activity subjects include cat behavior, needs, breeds, storybook cats, and celestial cats. Intermediate grade activity subjects include cat history, care, language, literary cats, and cats in art. (BC)

  20. Quantum turbulence

    NASA Astrophysics Data System (ADS)

    Skrbek, L.

    2011-12-01

    We review physical properties of quantum fluids He II and 3He-B, where quantum turbulence (QT) has been studied experimentally. Basic properties of QT in these working fluids are discussed within the phenomenological two-fluid model introduced by Landau. We consider counterflows in which the normal and superfluid components flow against each other, as well as co-flows in which the direction of the two fluids is the same. We pay special attention to the important case of zero temperature limit, where QT represents an interesting and probably the simplest prototype of three-dimensional turbulence in fluids. Experimental techniques to explore QT such as second sound attenuation, Andreev reflection, NMR, ion propagation are briefly introduced and results of various experiments on so-called Vinen QT and Kolmogorov QT both in He II and 3He are discussed, emphasizing similarities and differences between classical and quantum turbulence.

  1. DOD (USAF) turbulence accidents and incidents

    NASA Technical Reports Server (NTRS)

    Miller, Douglas

    1987-01-01

    A summary of Air Force turbulence related mishaps for the last ten years of Air Force mishaps is presented from a perspective of where it has been, where it is now, and where it is going. In addition to accounts of major mishaps, a summary of what actions were taken to preclude future similar mishaps is presented. Also, a discussion of some of the things being done now and being planned for the future to prevent turbulence related mishaps is presented.

  2. Estimating Atmospheric Turbulence From Flight Records

    NASA Technical Reports Server (NTRS)

    Wingrove, R. C.; Bach, R. E., Jr.; Schultz, T. A.

    1991-01-01

    Method for estimation of atmospheric turbulence encountered by airplanes utilizes wealth of data captured by multichannel digital flight-data recorders and air-traffic-control radar. Developed as part of continuing effort to understand how airplanes respond to such potentially hazardous phenomena as: clear-air turbulence generated by destabilized wind-shear layers above mountains and thunderstorms, and microbursts (intense downdrafts striking ground), associated with thunderstorms. Reconstructed wind fields used to predict and avoid future hazards.

  3. Turbulence in Compressible Flows

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Lecture notes for the AGARD Fluid Dynamics Panel (FDP) Special Course on 'Turbulence in Compressible Flows' have been assembled in this report. The following topics were covered: Compressible Turbulent Boundary Layers, Compressible Turbulent Free Shear Layers, Turbulent Combustion, DNS/LES and RANS Simulations of Compressible Turbulent Flows, and Case Studies of Applications of Turbulence Models in Aerospace.

  4. Turbulent spots in hypervelocity flow

    NASA Astrophysics Data System (ADS)

    Jewell, Joseph S.; Leyva, Ivett A.; Shepherd, Joseph E.

    2017-04-01

    The turbulent spot propagation process in boundary layer flows of air, nitrogen, carbon dioxide, and air/carbon dioxide mixtures in thermochemical nonequilibrium at high enthalpy is investigated. Experiments are performed in a hypervelocity reflected shock tunnel with a 5-degree half-angle axisymmetric cone instrumented with flush-mounted fast-response coaxial thermocouples. Time-resolved and spatially demarcated heat transfer traces are used to track the propagation of turbulent bursts within the mean flow, and convection rates at approximately 91, 74, and 63% of the boundary layer edge velocity, respectively, are observed for the leading edge, peak, and trailing edge of the spots. A simple model constructed with these spot propagation parameters is used to infer spot generation rates from observed transition onset to completion distance. Spot generation rates in air and nitrogen are estimated to be approximately twice the spot generation rates in air/carbon dioxide mixtures.

  5. Presumptive sialadenosis in a cat.

    PubMed

    Boydell, P; Pike, R; Crossley, D

    2000-12-01

    A cat was presented with signs associated with enlargement of the mandibular salivary glands. Histological findings were normal, consistent with a diagnosis of sialadenosis, and the cat responded to symptomatic treatment with oral phenobarbitone.

  6. Turbulent combustion

    SciTech Connect

    Talbot, L.; Cheng, R.K.

    1993-12-01

    Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

  7. Turbulence Modeling

    DTIC Science & Technology

    1991-10-01

    and complexity of thermochemistry . Accordingly a practical viewpoint is required to meet near-term work required for use in advanced CFD codes...teachers the opportunity to learn/explore/ teach turbulence issues. While such a product could be an invaluable eductaional tool (university), it also

  8. Turbulence modeling

    NASA Technical Reports Server (NTRS)

    Bardina, Jorge E.

    1995-01-01

    The objective of this work is to develop, verify, and incorporate the baseline two-equation turbulence models which account for the effects of compressibility into the three-dimensional Reynolds averaged Navier-Stokes (RANS) code and to provide documented descriptions of the models and their numerical procedures so that they can be implemented into 3-D CFD codes for engineering applications.

  9. On the initiation of surface waves by turbulent shear flow

    NASA Astrophysics Data System (ADS)

    Teixeira, M. A. C.; Belcher, S. E.

    2006-02-01

    An analytical model is developed for the initial stage of surface wave generation at an air-water interface by a turbulent shear flow in either the air or in the water. The model treats the problem of wave growth departing from a flat interface and is relevant for small waves whose forcing is dominated by turbulent pressure fluctuations. The wave growth is predicted using the linearised and inviscid equations of motion, essentially following Phillips [Phillips, O.M., 1957. On the generation of waves by turbulent wind. J. Fluid Mech. 2, 417-445], but the pressure fluctuations that generate the waves are treated as unsteady and related to the turbulent velocity field using the rapid-distortion treatment of Durbin [Durbin, P.A., 1978. Rapid distortion theory of turbulent flows. PhD thesis, University of Cambridge]. This model, which assumes a constant mean shear rate Γ, can be viewed as the simplest representation of an oceanic or atmospheric boundary layer. For turbulent flows in the air and in the water producing pressure fluctuations of similar magnitude, the waves generated by turbulence in the water are found to be considerably steeper than those generated by turbulence in the air. For resonant waves, this is shown to be due to the shorter decorrelation time of turbulent pressure in the air (estimated as ∝ 1/ Γ), because of the higher shear rate existing in the air flow, and due to the smaller length scale of the turbulence in the water. Non-resonant waves generated by turbulence in the water, although being somewhat gentler, are still steeper than resonant waves generated by turbulence in the air. Hence, it is suggested that turbulence in the water may have a more important role than previously thought in the initiation of the surface waves that are subsequently amplified by feedback instability mechanisms.

  10. Cat Scratch Disease (For Parents)

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Cat Scratch Disease KidsHealth > For Parents > Cat Scratch Disease Print A A A What's in ... Doctor en español Enfermedad por arañazo de gato Cat scratch disease is a bacterial infection that a ...

  11. Vibrational Schroedinger Cats

    NASA Technical Reports Server (NTRS)

    Kis, Z.; Janszky, J.; Vinogradov, An. V.; Kobayashi, T.

    1996-01-01

    The optical Schroedinger cat states are simple realizations of quantum states having nonclassical features. It is shown that vibrational analogues of such states can be realized in an experiment of double pulse excitation of vibrionic transitions. To track the evolution of the vibrational wave packet we derive a non-unitary time evolution operator so that calculations are made in a quasi Heisenberg picture.

  12. Characterizing Effects and Benefits of Beam Defocus on High Energy Laser Performance Under Thermal Blooming and Turbulence Conditions for Air-to-Ground Engagements

    DTIC Science & Technology

    2008-04-29

    3-13 3.4 Effect of increasing phase screens on peak irradiance . . . . . . 3- 14 3.5 Peak irradiance as a function of focal...4- 14 4.8 Peak irradiance as function of defocus for 200 kW baseline scenario (30% obscuration) under two turbulence...3- 14 3.3 Target plane peak irradiance values (W/m2) for given settings by range for otherwise baseline

  13. Prostatic carcinoma in two cats.

    PubMed

    Caney, S M; Holt, P E; Day, M J; Rudorf, H; Gruffydd-Jones, T J

    1998-03-01

    Clinical, radiological and pathological features of two cats with prostatic carcinoma are reported. In both cats the presenting history included signs of lower urinary tract disease with haematuria and dysuria. Prostatomegaly was visible radiographically in one cat; an irregular intraprostatic urethra was seen on retrograde contrast urethrography in both cats. In one of the cats, neoplasia was suspected on the basis of a transurethral catheter biopsy. Following a poor response to palliative treatment in both cases, euthanasia was performed with histological confirmation of the diagnosis.

  14. Efferent inhibition of carotid body chemoreception in chronically hypoxic cats.

    PubMed

    Lahiri, S; Smatresk, N; Pokorski, M; Barnard, P; Mokashi, A

    1983-11-01

    The effects of chronic hypoxia on carotid chemoreceptor afferent activity before and after sectioning the carotid sinus nerves (CSN) were studied in cats exposed to 10% O2 for 21-49 days in a chamber at sea level. For comparison, chronically normoxic cats at sea level were also studied. The cats were anesthetized, paucifiber preparation for the measurement of carotid chemosensory activity from a small slip of CSN was made, and their steady-state responses to 4-5 levels of arterial pressure of O2 (PaO2) at a constant PaCO2 and to 3-4 levels of PaCO2 in hyperoxia were measured before and after sectioning the CSN. The chemosensory response to hypoxia in the cats with intact CSN after chronic exposure to hypoxia was not reduced relative to the cats that breathed room air at sea level. Sectioning the CSN significantly augmented the chemosensory responses to hypoxia in all the chronically hypoxic but not significantly in the normoxic cats. The responses to moderate hypercapnia during hyperoxia were not significantly changed by cutting the CSN in either group. We conclude that there is a significant CSN efferent inhibition of chemosensory activity due to chronic hypoxia in the cat. This implies that without the efferent inhibition the hypoxic chemosensitivity is increased by chronic hypoxia.

  15. Genetic testing in domestic cats.

    PubMed

    Lyons, Leslie A

    2012-12-01

    Varieties of genetic tests are currently available for the domestic cat that support veterinary health care, breed management, species identification, and forensic investigations. Approximately thirty-five genes contain over fifty mutations that cause feline health problems or alterations in the cat's appearance. Specific genes, such as sweet and drug receptors, have been knocked-out of Felidae during evolution and can be used along with mtDNA markers for species identification. Both STR and SNP panels differentiate cat race, breed, and individual identity, as well as gender-specific markers to determine sex of an individual. Cat genetic tests are common offerings for commercial laboratories, allowing both the veterinary clinician and the private owner to obtain DNA test results. This article will review the genetic tests for the domestic cat, and their various applications in different fields of science. Highlighted are genetic tests specific to the individual cat, which are a part of the cat's genome.

  16. Controlling turbulence

    NASA Astrophysics Data System (ADS)

    Kühnen, Jakob; Hof, Björn

    2015-11-01

    We show that a simple modification of the velocity profile in a pipe can lead to a complete collapse of turbulence and the flow fully relaminarises. The annihilation of turbulence is achieved by a steady manipulation of the streamwise velocity component alone, greatly reducing control efforts. Several different control techniques are presented: one with a local modification of the flow profile by means of a stationary obstacle, one employing a nozzle injecting fluid through a small gap at the pipe wall and one with a moving wall, where a part of the pipe is shifted in the streamwise direction. All control techniques act on the flow such that the streamwise velocity profile becomes more flat and turbulence gradually grows faint and disappears. In a smooth straight pipe the flow remains laminar downstream of the control. Hence a reduction in skin friction by a factor of 8 and more can be accomplished. Stereoscopic PIV-measurements and movies of the development of the flow during relaminarisation are presented.

  17. Hyperthermic treatment of superficial tumors in cats and dogs.

    PubMed

    Grier, R L; Brewer, W G; Theilen, G H

    1980-08-01

    Local current field radiofrequency hyperthermia was applied to 33 superficial tumors in 11 cats and 5 dogs. Squamous cell carcinoma (SCC) in the cat was the most frequent tumor treated. Of 19 SCC in cats, 13 (68%) were reduced completely, combining complete and partial tumor reduction, there was an 89% favorable response to hyperthermia for SCC. A small number of other tumors such as fibrosarcoma in the cat and perianal tumors in the dog were favorably responsive. Local current field hyperthermia (50 C for 30 sec) resulted in destruction of tumor tissue as well as normal tissue. However, tissue destruction did not extend more than 2 or 3 mm from the electrodes. Ulcerative superficial tumors exposed to air rapidly reduced in size, and a dry eschar that developed fell off at 17 to 25 days.

  18. Peribronchiolar fibrosis in lungs of cats chronically exposed to diesel exhaust

    SciTech Connect

    Hyde, D.M.; Plopper, C.G.; Weir, A.J.; Murnane, R.D.; Warren, D.L.; Last, J.A.; Pepelko, W.E.

    1985-02-01

    This study reports the quantitative changes in the pulmonary proximal acinar region following chronic exposure to diesel exhaust and following an additional 6 months in clean air. Cats (13 months of age) from a minimum disease colony were exposed to clean air (eight cats for 27 months and nine cats for 33 months), diesel exhaust for 8 hours/day, 7 days/week (nine cats for 27 months), or diesel exhaust for 27 months followed by 6 months in clean air (10 cats). Morphologic and morphometric evaluation using light microscopy and scanning and transmission electron microscopy revealed two major exposure-related lesions in proximal acinar regions of lungs of cats: peribronchiolar fibrosis associated with significant increases in lymphocytes, fibroblasts, and interstitial macrophages containing diesel particulate-like inclusions and bronchiolar epithelial metaplasia associated with the presence of ciliated and basal cells and alveolar macrophages containing diesel particulate-like inclusions. Peribronchiolar fibrosis was greater at the end of the 6 months in clean air following exposure, whereas the bronchiolar epithelial metaplasia was most severe at the end of exposure. Following an additional 6 months in clean air the epithelium more closely resembled the control epithelial cell population. The labeling index of terminal bronchiolar epithelium was significantly increased at the end of exposure but was not significantly different from controls or exposed cats following an additional 6 months in clean air. The ultrastructural appearance of epithelial cells remained relatively unchanged following diesel exhaust exposure with the exception of diesel particulate-like inclusions.

  19. Big cat genomics.

    PubMed

    O'Brien, Stephen J; Johnson, Warren E

    2005-01-01

    Advances in population and quantitative genomics, aided by the computational algorithms that employ genetic theory and practice, are now being applied to biological questions that surround free-ranging species not traditionally suitable for genetic enquiry. Here we review how applications of molecular genetic tools have been used to describe the natural history, present status, and future disposition of wild cat species. Insight into phylogenetic hierarchy, demographic contractions, geographic population substructure, behavioral ecology, and infectious diseases have revealed strategies for survival and adaptation of these fascinating predators. Conservation, stabilization, and management of the big cats are important areas that derive benefit from the genome resources expanded and applied to highly successful species, imperiled by an expanding human population.

  20. Cat scratch disease.

    PubMed

    Bozhkov, V; Madjov, R; Plachkov, I; Arnaudov, P; Chernopolsky, P; Krasnaliev, I

    2014-01-01

    Approximately 24,000 people are infected with cat scratch disease (CSD) every year. CSD is caused by the bacteria Bartonella henselae, a gram-negative bacteria most often transmitted to humans through a bite or scratch from an infected cat or kitten. Although CSD is often a benign and self-limiting condition, it can affect any major organ system in the body, manifesting in different ways and sometimes leading to lifelong sequelae. It is a disease that is often overlooked in primary care because of the wide range of symptom presentation and relative rarity of serious complications. It is important for health care providers to recognize patients at risk for CSD, know what laboratory testing and treatments are available, and be aware of complications that may arise from this disease in the future.

  1. Magnetohydrodynamic Turbulence

    NASA Astrophysics Data System (ADS)

    Montgomery, David C.

    2004-01-01

    Magnetohydrodynamic (MHD) turbulence theory is modeled on neutral fluid (Navier-Stokes) turbulence theory, but with some important differences. There have been essentially no repeatable laboratory MHD experiments wherein the boundary conditions could be controlled or varied and a full set of diagnostics implemented. The equations of MHD are convincingly derivable only in the limit of small ratio of collision mean-free-paths to macroscopic length scales, an inequality that often goes the other way for magnetofluids of interest. Finally, accurate information on the MHD transport coefficients-and thus, the Reynolds-like numbers that order magnetofluid behavior-is largely lacking; indeed, the algebraic expressions used for such ingredients as the viscous stress tensor are often little more than wishful borrowing from fluid mechanics. The one accurate thing that has been done extensively and well is to solve the (strongly nonlinear) MHD equations numerically, usually in the presence of rectangular periodic boundary conditions, and then hope for the best when drawing inferences from the computations for those astrophysical and geophysical MHD systems for which some indisputably turbulent detailed data are available, such as the solar wind or solar prominences. This has led to what is perhaps the first field of physics for which computer simulations are regarded as more central to validating conclusions than is any kind of measurement. Things have evolved in this way due to a mixture of the inevitable and the bureaucratic, but that is the way it is, and those of us who want to work on the subject have to live with it. It is the only game in town, and theories that have promised more-often on the basis of some alleged ``instability''-have turned out to be illusory.

  2. A turbulence model for buoyant flows based on vorticity generation.

    SciTech Connect

    Domino, Stefan Paul; Nicolette, Vernon F.; O'Hern, Timothy John; Tieszen, Sheldon R.; Black, Amalia Rebecca

    2005-10-01

    A turbulence model for buoyant flows has been developed in the context of a k-{var_epsilon} turbulence modeling approach. A production term is added to the turbulent kinetic energy equation based on dimensional reasoning using an appropriate time scale for buoyancy-induced turbulence taken from the vorticity conservation equation. The resulting turbulence model is calibrated against far field helium-air spread rate data, and validated with near source, strongly buoyant helium plume data sets. This model is more numerically stable and gives better predictions over a much broader range of mesh densities than the standard k-{var_epsilon} model for these strongly buoyant flows.

  3. Modeling of Turbulent Swirling Flows

    NASA Technical Reports Server (NTRS)

    Shih, Tsan-Hsing; Zhu, Jiang; Liou, William; Chen, Kuo-Huey; Liu, Nan-Suey; Lumley, John L.

    1997-01-01

    Aircraft engine combustors generally involve turbulent swirling flows in order to enhance fuel-air mixing and flame stabilization. It has long been recognized that eddy viscosity turbulence models are unable to appropriately model swirling flows. Therefore, it has been suggested that, for the modeling of these flows, a second order closure scheme should be considered because of its ability in the modeling of rotational and curvature effects. However, this scheme will require solution of many complicated second moment transport equations (six Reynolds stresses plus other scalar fluxes and variances), which is a difficult task for any CFD implementations. Also, this scheme will require a large amount of computer resources for a general combustor swirling flow. This report is devoted to the development of a cubic Reynolds stress-strain model for turbulent swirling flows, and was inspired by the work of Launder's group at UMIST. Using this type of model, one only needs to solve two turbulence equations, one for the turbulent kinetic energy k and the other for the dissipation rate epsilon. The cubic model developed in this report is based on a general Reynolds stress-strain relationship. Two flows have been chosen for model evaluation. One is a fully developed rotating pipe flow, and the other is a more complex flow with swirl and recirculation.

  4. A review of over three decades of research on cat-human and human-cat interactions and relationships.

    PubMed

    Turner, Dennis C

    2017-01-22

    This review article covers research conducted over the last three decades on cat-human and human-cat interactions and relationships, especially from an ethological point of view. It includes findings on cat-cat and cat-human communication, cat personalities and cat-owner personalities, the effects of cats on humans, and problems caused by cats.

  5. Raccoonpox in a Canadian cat.

    PubMed

    Yager, Julie A; Hutchison, Lisa; Barrett, John W

    2006-12-01

    Poxvirus infections affecting the skin of cats are extremely rare in North America, in contrast to Europe where cowpox virus is well recognized as an accidental pathogen in cats that hunt small rodents. The virus or viruses responsible for the anecdotal cases in North America have never been characterized. This paper reports a case of raccoonpox infection in a Canadian cat. Biopsy of the initial ulcerative lesion on the forepaw revealed ballooning degeneration of surface and follicular keratinoctyes. Infected cells contained large eosinophilic type A inclusions. Electron microscopic examination revealed virions of an orthopoxvirus, subsequently identified as raccoonpox by polymerase chain reaction and gene sequencing. The cat made a full recovery.

  6. External hydrocephalus in two cats.

    PubMed

    Dewey, Curtis W; Coates, Joan R; Ducoté, Julie M; Stefanacci, Joseph D; Walker, Michael A; Marino, Dominic J

    2003-01-01

    External hydrocephalus describes an accumulation of cerebrospinal fluid (CSF) between the cerebral hemispheres and the overlying arachnoid membrane, rather than within the lateral ventricles. Two young cats with encephalopathic signs were diagnosed with external hydrocephalus, one via magnetic resonance imaging and one via computed tomography. Both cats had abnormally large, broad heads, with no evidence of open fontanelles. A surgical shunt was placed in each cat to divert the accumulated CSF within the cranial cavity to the peritoneal space. Both cats improved dramatically soon after surgical shunting was performed, and they continue to do well clinically, approximately 42 months and 8 months postoperatively, respectively.

  7. Aspects of Turbulent / Non-Turbulent Interfaces

    NASA Technical Reports Server (NTRS)

    Bisset, D. K.; Hunt, J. C. R.; Rogers, M. M.; Koen, Dennis (Technical Monitor)

    1999-01-01

    A distinct boundary between turbulent and non-turbulent regions in a fluid of otherwise constant properties is found in many laboratory and engineering turbulent flows, including jets, mixing layers, boundary layers and wakes. Generally, the flow has mean shear in at least one direction within t he turbulent zone, but the non-turbulent zones have no shear (adjacent laminar shear is a different case, e.g. transition in a boundary layer). There may be purely passive differences between the turbulent and non-turbulent zones, e.g. small variations in temperature or scalar concentration, for which turbulent mixing is an important issue. The boundary has several major characteristics of interest for the present study. Firstly, the boundary advances into the non-turbulent fluid, or in other words, nonturbulent fluid is entrained. Secondly, the change in turbulence properties across the boundary is remarkably abrupt; strong turbulent motions come close to the nonturbulent fluid, promoting entrainment. Thirdly, the boundary is irregular with a continually changing convoluted shape, which produces statistical intermittency. Its shape is contorted at all scales of the turbulent motion.

  8. Turbulence and turbulent mixing in natural fluids

    NASA Astrophysics Data System (ADS)

    Gibson, Carl H.

    2010-12-01

    Turbulence and turbulent mixing in natural fluids begin with big bang turbulence powered by spinning combustible combinations of Planck particles and Planck antiparticles. Particle prograde accretions on a spinning pair release 42% of the particle rest mass energy to produce more fuel for turbulent combustion. Negative viscous stresses and negative turbulence stresses work against gravity, extracting mass-energy and space-time from the vacuum. Turbulence mixes cooling temperatures until strong-force viscous stresses freeze out turbulent mixing patterns as the first fossil turbulence. Cosmic microwave background temperature anisotropies show big bang turbulence fossils along with fossils of weak plasma turbulence triggered as plasma photon-viscous forces permitting gravitational fragmentation on supercluster to galaxy mass scales. Turbulent morphologies and viscous-turbulent lengths appear as linear gas-protogalaxy-clusters in the Hubble ultra-deep field at z~7. Protogalaxies fragment into Jeans mass clumps of primordial-gas planets at decoupling: the dark matter of galaxies. Shortly after the plasma-to-gas transition, planet mergers produce stars that explode on overfeeding to fertilize and distribute the first life.

  9. Group 1 and 2 Dermatophagoides house dust mite allergens in the microenvironment of cats.

    PubMed

    Loft, Klaus Earl; Rosser, Edmund J

    2010-04-01

    House dust mite allergens (HDMAs) are some of the most common allergens associated with allergic diseases in humans and dogs. The purpose of this study was to determine whether HDMAs could be detected in cat-associated household microenvironments. From 50 cat-only households with 95 cats, dust samples were collected by vacuuming for 2 min m(-2) from three areas where cats slept or rested regularly from September to October 2006. Relative humidity and temperature were measured in each household using a data logger. Each owner completed a questionnaire on potential factors that might influence the prevalence of house dust mites (HDMs). Dust samples were analysed utilizing an ELISA for Der p 1, Der f 1 and HDM group 2 allergens. In 38 of 50 households there was greater than 2 microg g(-1) of dust for at least one HDMA. Using stepwise logistic regression, factors associated with increased HDMA levels included: free-standing houses, number of humans in household, longhaired cats and age of the cat. Factors associated with decreased HDMA concentrations included: forced air heating and central air conditioning, less than 50% carpeting of the home, use of flea control, cats suffering from dermatological disease and the average temperature of the household. Many sleeping/resting areas utilized by cats contain sufficiently high levels of HDMAs to be potential sources of sensitization. This finding should lead to further determination of the role of HDMs in cats suffering from putative allergic conditions such as atopic dermatitis or asthma.

  10. Statistical turbulence theory and turbulence phenomenology

    NASA Technical Reports Server (NTRS)

    Herring, J. R.

    1973-01-01

    The application of deductive turbulence theory for validity determination of turbulence phenomenology at the level of second-order, single-point moments is considered. Particular emphasis is placed on the phenomenological formula relating the dissipation to the turbulence energy and the Rotta-type formula for the return to isotropy. Methods which deal directly with most or all the scales of motion explicitly are reviewed briefly. The statistical theory of turbulence is presented as an expansion about randomness. Two concepts are involved: (1) a modeling of the turbulence as nearly multipoint Gaussian, and (2) a simultaneous introduction of a generalized eddy viscosity operator.

  11. Systemic cat scratch disease.

    PubMed

    Liao, Hui-Min; Huang, Fu-Yuan; Chi, Hsin; Wang, Nieu-Lu; Chen, Be-Fong

    2006-08-01

    Systemic cat scratch disease (CSD) is often associated with prolonged fever and microabscesses in the liver and/or spleen. We report a case of systemic CSD with hepatic, splenic and renal involvement in an aboriginal child in Taiwan. A previously healthy 9-year-old girl had an intermittent fever for about 17 days, and complained of abdominal pain, headache and weight loss. Abdominal computed tomography showed multiple tiny hypodense nodular lesions in the spleen and both kidneys. Laparotomy revealed multiple soft, whitish-tan lesions on the surface of the liver and spleen. Histopathologic examination of a biopsy specimen of the spleen showed necrotizing granulomatous inflammation with central necrosis surrounded by epithelioid cells and occasional Langhans' giant cells, strongly suggestive of Bartonella henselae infection. History revealed close contact with a cat. B. henselae DNA was detected by polymerase chain reaction in the tissue specimen, and the single antibody titer against B. henselae was greater than 1:2048. These results confirmed the diagnosis of visceral CSD caused by B. henselae. The patient's symptoms resolved after treatment with rifampin and tetracycline. This case illustrates the need for inclusion of systemic CSD in patients with fever of unknown origin and abdominal pain.

  12. Internal structure of a premixed turbulent flame

    SciTech Connect

    Rajan, S.; Smith, J.R.; Rambach, G.D.

    1982-10-01

    A pulsed laser and a multielement detector have been used to make instantaneous Rayleigh profiles along a line through a turbulent flame front thus eliminating the effects of flame front motion. The flame front in a premixed turbulent flame moves randomly about a mean position, giving rise to the visually observed flame brush or time-averaged flame thickness which is larger than the instantaneous thickness of the reaction zone. The physical characteristics and statistical properties of such turbulent flames reported previously were deduced from the time histories of Rayleigh scattered laser light at one or two points within the reaction zone. The study was conducted on a premixed propane-air flame stabilized on a rod at the exit plane of a square burner. Turbulence-producing screens below the burner exit controlled turbulent length scales while intensity was controlled with inlet mixture velocity. Turbulence properties of the cold reactants were determined by hot-wire anemometry. Mean and fluctuating velocity in the unburnt and burnt gases were measured using laser Doppler velocimetry. At the low level of turbulence studied, the instantaneous flame front thickness was found to be only slightly greater than the laminar flame thickness, and the magnitude of the density fluctuations only slightly greater than the cold flow turbulence intensity. Mean and rms values of density and velocity; density and velocity probability density functions; spatial density correlations; and comparison of data with the Bray-Moss-Libby model are presented.

  13. Flames in fractal grid generated turbulence

    NASA Astrophysics Data System (ADS)

    Goh, K. H. H.; Geipel, P.; Hampp, F.; Lindstedt, R. P.

    2013-12-01

    Twin premixed turbulent opposed jet flames were stabilized for lean mixtures of air with methane and propane in fractal grid generated turbulence. A density segregation method was applied alongside particle image velocimetry to obtain velocity and scalar statistics. It is shown that the current fractal grids increase the turbulence levels by around a factor of 2. Proper orthogonal decomposition (POD) was applied to show that the fractal grids produce slightly larger turbulent structures that decay at a slower rate as compared to conventional perforated plates. Conditional POD (CPOD) was also implemented using the density segregation technique and the results show that CPOD is essential to segregate the relative structures and turbulent kinetic energy distributions in each stream. The Kolmogorov length scales were also estimated providing values ∼0.1 and ∼0.5 mm in the reactants and products, respectively. Resolved profiles of flame surface density indicate that a thin flame assumption leading to bimodal statistics is not perfectly valid under the current conditions and it is expected that the data obtained will be of significant value to the development of computational methods that can provide information on the conditional structure of turbulence. It is concluded that the increase in the turbulent Reynolds number is without any negative impact on other parameters and that fractal grids provide a route towards removing the classical problem of a relatively low ratio of turbulent to bulk strain associated with the opposed jet configuration.

  14. Ribbon turbulence

    NASA Astrophysics Data System (ADS)

    Venaille, Antoine; Nadeau, Louis-Philippe; Vallis, Geoffrey

    2014-12-01

    We investigate the non-linear equilibration of a two-layer quasi-geostrophic flow in a channel with an initial eastward baroclinically unstable jet in the upper layer, paying particular attention to the role of bottom friction. In the limit of low bottom friction, classical theory of geostrophic turbulence predicts an inverse cascade of kinetic energy in the horizontal with condensation at the domain scale and barotropization in the vertical. By contrast, in the limit of large bottom friction, the flow is dominated by ribbons of high kinetic energy in the upper layer. These ribbons correspond to meandering jets separating regions of homogenized potential vorticity. We interpret these results by taking advantage of the peculiar conservation laws satisfied by this system: the dynamics can be recast in such a way that the initial eastward jet in the upper layer appears as an initial source of potential vorticity levels in the upper layer. The initial baroclinic instability leads to a turbulent flow that stirs this potential vorticity field while conserving the global distribution of potential vorticity levels. Statistical mechanical theory of the 1 1/2 layer quasi-geostrophic model predicts the formation of two regions of homogenized potential vorticity separated by a minimal interface. We explain that cascade phenomenology leads to the same result. We then show that the dynamics of the ribbons results from a competition between a tendency to reach the equilibrium state and baroclinic instability that induces meanders of the interface. These meanders intermittently break and induce potential vorticity mixing, but the interface remains sharp throughout the flow evolution. We show that for some parameter regimes, the ribbons act as a mixing barrier which prevents relaxation toward equilibrium, favouring the emergence of multiple zonal (eastward) jets.

  15. Hypertensive retinopathy in a cat

    PubMed Central

    Van Boxtel, Sherry A.

    2003-01-01

    A 12-year-old cat presented for sudden blindness was diagnosed with hypertensive retinopathy on the basis of ophthalmologic and ultrasonic examination. Renal failure due to a large intranephric cyst obstructing the right ureter and renal artery was the suggested cause of the systemic hypertension. The cat died 8 hours after unilateral nephrectomy. PMID:12650046

  16. Oral masses in two cats.

    PubMed

    Bock, P; Hach, V; Baumgärtner, W

    2011-07-01

    Incisional biopsies from the oral cavity of 2 adult cats were submitted for histological investigation. Cat No. 1 showed a solitary well-circumscribed neoplasm in the left mandible. Cat No. 2 demonstrated a diffusely infiltrating neoplasm in the left maxilla. Both tumors consisted of medium-size epithelial cells embedded in a fibrovascular stroma. The mitotic index was 0 to 1 mitosis per high-power field. The epithelial cells showed an irregular arrangement forming nests or streams in cat No. 1, whereas a palisading growth was noted in cat No. 2. Both tumors, especially that of cat No. 1, showed multifocal accumulations of amyloid as confirmed by Congo red staining and a distinct green birefringence under polarized light, which lacked cytokeratin immunoreactivity as well as and AL and AA amyloid immunoreactivity. In addition, the amyloid in cat No. 2 was positive for the odontogenic ameloblast-associated protein, formerly termed APin. In sum, both cats suffered from an amyloid-producing odontogenic tumor, but their tumors varied with respect to morphology and type of amyloid produced.

  17. College Students and Their Cats

    ERIC Educational Resources Information Center

    Weinstein, Lawrence; Alexander, Ralph

    2010-01-01

    Twenty-two Siamese and 32 mixed breed cats' personalities were rated by their respective college student owners and compared. Further, the owners' self rated personality traits were correlated with the pets'; significant Siamese and Mixed differences and correlations were obtained. These are the first data to examine breed of cat on a personality…

  18. CONTRACT ADMINISTRATIVE TRACKING SYSTEM (CATS)

    EPA Science Inventory

    The Contract Administrative Tracking System (CATS) was developed in response to an ORD NHEERL, Mid-Continent Ecology Division (MED)-recognized need for an automated tracking and retrieval system for Cost Reimbursable Level of Effort (CR/LOE) Contracts. CATS is an Oracle-based app...

  19. Advanced Turbulence Modeling Concepts

    NASA Technical Reports Server (NTRS)

    Shih, Tsan-Hsing

    2005-01-01

    The ZCET program developed at NASA Glenn Research Center is to study hydrogen/air injection concepts for aircraft gas turbine engines that meet conventional gas turbine performance levels and provide low levels of harmful NOx emissions. A CFD study for ZCET program has been successfully carried out. It uses the most recently enhanced National combustion code (NCC) to perform CFD simulations for two configurations of hydrogen fuel injectors (GRC- and Sandia-injector). The results can be used to assist experimental studies to provide quick mixing, low emission and high performance fuel injector designs. The work started with the configuration of the single-hole injector. The computational models were taken from the experimental designs. For example, the GRC single-hole injector consists of one air tube (0.78 inches long and 0.265 inches in diameter) and two hydrogen tubes (0.3 inches long and 0.0226 inches in diameter opposed at 180 degree). The hydrogen tubes are located 0.3 inches upstream from the exit of the air element (the inlet location for the combustor). To do the simulation, the single-hole injector is connected to a combustor model (8.16 inches long and 0.5 inches in diameter). The inlet conditions for air and hydrogen elements are defined according to actual experimental designs. Two crossing jets of hydrogen/air are simulated in detail in the injector. The cold flow, reacting flow, flame temperature, combustor pressure and possible flashback phenomena are studied. Two grid resolutions of the numerical model have been adopted. The first computational grid contains 0.52 million elements, the second one contains over 1.3 million elements. The CFD results have shown only about 5% difference between the two grid resolutions. Therefore, the CFD result obtained from the model of 1.3-million grid resolution can be considered as a grid independent numerical solution. Turbulence models built in NCC are consolidated and well tested. They can handle both coarse and

  20. The HelCat dual-source plasma device.

    PubMed

    Lynn, Alan G; Gilmore, Mark; Watts, Christopher; Herrea, Janis; Kelly, Ralph; Will, Steve; Xie, Shuangwei; Yan, Lincan; Zhang, Yue

    2009-10-01

    The HelCat (Helicon-Cathode) device has been constructed to support a broad range of basic plasma science experiments relevant to the areas of solar physics, laboratory astrophysics, plasma nonlinear dynamics, and turbulence. These research topics require a relatively large plasma source capable of operating over a broad region of parameter space with a plasma duration up to at least several milliseconds. To achieve these parameters a novel dual-source system was developed utilizing both helicon and thermionic cathode sources. Plasma parameters of n(e) approximately 0.5-50 x 10(18) m(-3) and T(e) approximately 3-12 eV allow access to a wide range of collisionalities important to the research. The HelCat device and initial characterization of plasma behavior during dual-source operation are described.

  1. Seasonality in submesoscale turbulence.

    PubMed

    Callies, Jörn; Ferrari, Raffaele; Klymak, Jody M; Gula, Jonathan

    2015-04-21

    Although the strongest ocean surface currents occur at horizontal scales of order 100 km, recent numerical simulations suggest that flows smaller than these mesoscale eddies can achieve important vertical transports in the upper ocean. These submesoscale flows, 1-100 km in horizontal extent, take heat and atmospheric gases down into the interior ocean, accelerating air-sea fluxes, and bring deep nutrients up into the sunlit surface layer, fueling primary production. Here we present observational evidence that submesoscale flows undergo a seasonal cycle in the surface mixed layer: they are much stronger in winter than in summer. Submesoscale flows are energized by baroclinic instabilities that develop around geostrophic eddies in the deep winter mixed layer at a horizontal scale of order 1-10 km. Flows larger than this instability scale are energized by turbulent scale interactions. Enhanced submesoscale activity in the winter mixed layer is expected to achieve efficient exchanges with the permanent thermocline below.

  2. CFD analysis on a turbulence generator of medium consistency pump

    NASA Astrophysics Data System (ADS)

    Ma, X. D.; Wu, D. Z.; Huang, D. S.; Yu, H.; Wang, L. Q.

    2013-12-01

    Medium concentration paper suspension is a water-air-fibre three phase suspension. It has complicated physical features. When concentration exceeds 7%, it stops flowing and acts like a solid. A generator suspension is installed before the impeller to disturb the flocs and networks to make it start to flow. In this paper, CFD method is adopted to study the effects of the turbulence generator. As there is not a mature model to describe the characteristic of pulp suspension, Newtonian fluid is used to get the general property of the turbulence generator. In the CFD simulation, apparent viscosity of the pulp suspension is used to characterize the mixture. Firstly, numerical method is applied to get the turbulence generator properties in different rotational speed and different viscosity. From another point of view, air contained in the suspension is separate initially by means of centrifugal force. As it is difficult to describe a practical model of pulp suspension, it is simplified to be a water-air two-phase mixture. Several air contents are simulated to study the air distribution in the turbulence generator. The results show that there are three main effects of turbulence generator. Firstly, it has an entrainment effect of the suspension to make it into the pump. Secondly, it stirs the pulp suspension to bring it into flowing. Last, air is centralized in the shaft centre and pre-separated in the turbulence generator. So, the turbulence generator can pre-treat the pulp suspension to make the MC pump transport suspension successfully.

  3. How cats lap

    NASA Astrophysics Data System (ADS)

    Stocker, Roman; Reis, Pedro; Jung, Sunghwan; Aristoff, Jeffrey

    2010-11-01

    We studied the lapping of the domestic cat (Felis catus) by combining high-speed photography with a laboratory model of lapping. We found that Felis catus laps by a subtle mechanism based on water adhesion to the dorsal side of the tongue and the creation of a liquid column, exploiting inertia to defeat gravity and pull liquid into the mouth. The competition between inertia and gravity controls the pinch-off time of the column, determining the optimal lapping frequency, f. Felis catus was found to operate near the optimum and theoretical analysis yielded a scaling, f ˜M-1/6, of lapping frequency with animal mass, M. This prediction was verified by measuring lapping frequency across felids, from ocelots to lions, suggesting that the lapping mechanism is conserved among felines.

  4. Turbulence Modulation and Particle Segregation in a Turbulent Channel Flow

    NASA Astrophysics Data System (ADS)

    Fong, Kee Onn; Toloui, Mostafa; Amili, Omid; Hong, Jiarong; Coletti, Filippo

    2016-11-01

    Particle-laden flows are ubiquitous in biological, environmental, and engineering flows, but our understanding of the mechanism by which particles modulate turbulence is incomplete. Simulations involve a wide range of scales, and shall be corroborated by measurements that reconstruct the motion of both the continuous and dispersed phases. We present experimental observations on the interaction between inertial particles and turbulent flow through a vertical channel in two-way coupled regime. The working fluid is air laden with size-selected glass particles, which we investigate by planar particle image velocimetry and digital inline holography. Unlike most previous experiments, we focus on a regime in which particle segregation and turbulence modulation are both strong. PIV shows that turbulence modulation is especially pronounced near the wall, where particles accumulate by turbophoresis. The segregation, however, is much weaker than what suggested by one-way coupled simulations. Results from digital holography confirm the trends in particle concentration and velocities, and additionally provide information on the three-dimensional clustering. The findings are compared to previous investigations and discussed in the context of modeling strategies.

  5. Simulation of the Turbulent air Flow Over a Circular Cavity with a Variable Opening Angle in an U-Shaped Channel

    NASA Astrophysics Data System (ADS)

    Isaev, S. A.; Baranov, P. A.; Usachov, A. E.; Zhukova, Yu. V.; Vysotskaya, A. A.; Malyshkin, D. A.

    2015-07-01

    A numerical investigation of the influence of the opening angle of a circular cavity in an U-shaped channel and the Reynolds number of a fluid fl ow in this channel on the local characteristics and turbulence of this fl ow has been performed based on the solution of the Reynolds equations, closed by the old and new Menter shear-stress transfer models and two variants of this model accounting for the curvature of streamlines, with the use of multiblock computational technologies realized in the VP2/3 package. The results of calculations were compared with each other and with experimental data of I. Castro and R. Savelsberg. This comparison has shown that the best agreement between the numerical predictions and experiments is obtained in the case where calculations are performed within the framework of the Leshtsiner-Rody-Isaev approach with correction for the eddy viscosity of the fluid fl ow. It was established that with increase in the Reynolds number and in the opening angle of the cavity the circulation flow in the near-wall layer of the vortex trapped in the cavity intensifies at a practically constant vorticity in the core of the vortex.

  6. Market Assessment of Forward-Looking Turbulence Sensing Systems

    NASA Technical Reports Server (NTRS)

    Kauffmann, Paul; Sousa-Poza, Andres

    2001-01-01

    In recognition of the importance of turbulence mitigation as a tool to improve aviation safety, NASA's Aviation Safety Program developed a Turbulence Detection and Mitigation Sub-element. The objective of this effort is to develop highly reliable turbulence detection technologies for commercial transport aircraft to sense dangerous turbulence with sufficient time warning so that defensive measures can be implemented and prevent passenger and crew injuries. Current research involves three forward sensing products to improve the cockpit awareness of possible turbulence hazards. X-band radar enhancements will improve the capabilities of current weather radar to detect turbulence associated with convective activity. LIDAR (Light Detection and Ranging) is a laser-based technology that is capable of detecting turbulence in clear air. Finally, a possible Radar-LIDAR hybrid sensor is envisioned to detect the full range of convective and clear air turbulence. To support decisions relating to the development of these three forward-looking turbulence sensor technologies, the objective of this study was defined as examination of cost and implementation metrics. Tasks performed included the identification of cost factors and certification issues, the development and application of an implementation model, and the development of cost budget/targets for installing the turbulence sensor and associated software devices into the commercial transport fleet.

  7. The problem of atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Toomre, J.; HILL; MERRYFIELD; GOUGH

    1984-01-01

    All ground-based observations of the solar five-minute oscillations are affected by turbulence in the Earth's atmosphere that leads to substantial refractive index variations. The turbulent motions serve to mix an air mass that is thermally stratified in the vertical, thereby producing intermittent thermal fluctuations over a wide range of heights in the atmosphere. These thermal structures yield refractive index changes that deflect the light path in a complicated way, producing intricate variations of amplitude and phase in what might have started out as simple plane waves. Since the fluid turbulence is statistical in nature, so too is the optical turbulence which is an integral measure of the refractive index changes along the light travel path. All of this produces what is usually called atmospheric seeing, which consists of image motion, blurring and distortion across the field of view. The effects of atmospheric seeing upon observations of five-minute oscillations carried out from the ground were assessed. This will help to provide a baseline estimate of the scienctific benefits that might accrue if one were able to observe the same oscillations from a space observatory unfettered by seeing effects.

  8. Turbulent Flow Between Rotating Cylinders

    NASA Technical Reports Server (NTRS)

    Shih-I, Pai

    1943-01-01

    The turbulent air flow between rotating cylinders was investigated. The distributions of mean speed and of turbulence were measured in the gap between a rotating inner and a stationary outer cylinder. The measurements led to the conclusion that the turbulent flow in the gap cannot be considered two dimensional, but that a particular type of secondary motion takes place. It is shown that the experimentally found velocity distribution can be fully understood under the assumption that this secondary motion consists of three-dimensional ring-shape vortices. The vortices occur only in pairs, and their number and size depend on the speed of the rotating cylinder; the number was found to decrease with increasing speed. The secondary motion has an essential part in the transmission of the moment of momentum. In regions where the secondary motion is negligible, the momentum transfer follows the laws known for homologous turbulence. Ring-shape vortices are known to occur in the laminar flow between rotating cylinders, but it was hitherto unknown that they exist even at speeds that are several hundred times the critical limit.

  9. Mycobacterium bovis in Argentina: isolates from cats typified by spoligotyping.

    PubMed

    Zumárraga, M J; Vivot, M Martínez; Marticorena, D; Bernardelli, A; Fasán, R; Iachini, R; Cataldi, A A

    2009-01-01

    In the present work, 19 Mycobacterium bovis isolates from different cats were typified by spoligotyping. We detected nine spoligotypes. There was only one cluster, which grouped 11 of the isolates (57.9%), showing the main spoligotype from cattle from Argentina. The rest of the spoligotypes presented only one isolate each. Five of them were not found in cattle, and were unique and exclusive of cats. The isolates studied show that tuberculosis of bovine origin in cats constitutes a potential public health problem in Buenos Aires region. The identification of genotypes from non-natural hosts could contribute to understand the spread of bovine tuberculosis. This is the first report showing genetic profiles of M. bovis isolates in felines from Argentina.

  10. Pemphigus foliaceus in a cat.

    PubMed

    Kofod, H

    1993-01-16

    The author's cat started to develop the signs of pemphigus foliaceus one month after he returned home after six months absence. The initial signs included dry coughing and difficulty with purring and swallowing, followed by typical changes of the skin. The cat was treated by a combination of chrysotherapy and systemic glucocorticoid injections, and remained free of clinical signs for one and a half years. The cat then relapsed and showed the initial signs except that coughing was not observed. It was treated as before but after a second relapse and the same treatment it slowly developed a general weakness and was euthanased.

  11. Turbulent Heat Fluxes during an Intense Cold-Air Outbreak over the Kuroshio Extension Region: Results from a High-Resolution Coupled Atmosphere-Ocean Model

    DTIC Science & Technology

    2011-02-12

    agreement with AMTEX observa- tions and sensible and latent heat fluxes of 300 and 700 Wm 2, respectively, which are close to the observed values. Xue et...1,300 Wm 2, respectively. Modeling of cold-air outbreaks using a full three-dimensional coupled atmosphere–ocean model was done for the Gulf Stream for a...latent heat flux of 575 Wm 2. In this study, we present a case from 30 January through 6 February 2005 where the formation of cyclo- nes followed the

  12. In-Service Evaluation of the Turbulence Auto-PIREP System and Enhanced Turbulence Radar Technologies

    NASA Technical Reports Server (NTRS)

    Prince, Jason B.; Buck, Bill K.; Robinson, Paul A.; Ryan, Tim

    2007-01-01

    From August 2003 to December 2006, In-Service Evaluations (ISE) of the Turbulence Auto-PIREP System (TAPS) and Enhanced Turbulence (E-Turb) Radar, technologies developed in NASA's Turbulence Prediction and Warning System (TPAWS) element of its Aviation Safety and Security Program (AvSSP), were conducted. NASA and AeroTech Research established an industry team comprising AeroTech, Delta Air Lines, Rockwell Collins, and ARINC to conduct the ISEs. The technologies were installed on Delta aircraft and their effectiveness was evaluated in day-to-day operations. This report documents the establishment and conduct of the ISEs and presents results and feedback from various users.

  13. [Prevalence of Tritrichomonas foetus among Dutch cats].

    PubMed

    van Doorn, D C K; de Bruin, M J; Jorritsma, R A; Ploeger, H W; Schoormans, A

    2009-09-01

    Prevalence of Tritrichomonas foetus among Dutch cats The aim of this study was to determine the prevalence of and risk factors for, Tritrichomonas foetus among cats in the Netherlands. A total of 154 faecal samples were collected from three groups of cats: cats with diarrhoea (n=53), cattery cats (n=47), and healthy pet cats (n=54). Faecal samples were examined with a T. foetus specific real-time PCR. All PCR-positive samples were run on gel electrophoresis for definitive diagnosis. The prevalence of T. foetus was 2% among cats with diarrhoea and 4% among cattery cats; T. foetus was not prevalent among pet cats (none of the samples tested positive). Questionnaires had been distributed to cat and cattery owners to determine risk factors for T. foetus, but the low prevalence precluded statistical analysis of the questionnaire results.

  14. Dog and cat bites.

    PubMed

    Ellis, Robert; Ellis, Carrie

    2014-08-15

    Animal bites account for 1% of all emergency department visits in the United States and more than $50 million in health care costs per year. Most animal bites are from a dog, usually one known to the victim. Most dog bite victims are children. Bite wounds should be cleaned, copiously irrigated with normal saline using a 20-mL or larger syringe or a 20-gauge catheter attached to the syringe. The wound should be explored for tendon or bone involvement and possible foreign bodies. Wounds may be closed if cosmetically favorable, such as wounds on the face or gaping wounds. Antibiotic prophylaxis should be considered, especially if there is a high risk of infection, such as with cat bites, with puncture wounds, with wounds to the hand, and in persons who are immunosuppressed. Amoxicillin/clavulanate is the first-line prophylactic antibiotic. The need for rabies prophylaxis should be addressed with any animal bite because even domestic animals are often unvaccinated. Postexposure rabies prophylaxis consists of immune globulin at presentation and vaccination on days 0, 3, 7, and 14. Counseling patients and families about animal safety may help decrease animal bites. In most states, physicians are required by law to report animal bites.

  15. Cat eye syndrome

    PubMed Central

    Sharma, Deepak; Murki, Srinivas; Pratap, Tejo; Vasikarla, Madhavi

    2014-01-01

    A full-term female baby, a product of non-consanguineous marriage, was born at 37 weeks of gestation with a birth weight of 2.08 kg. Antenatal scan at 31 weeks revealed complex congenital heart disease with a hypoplastic right ventricle, pulmonary atresia and an intact septum. Immediately after birth, the infant was shifted to the nursery and was started on intravenous fluids and infusion prostaglandin E1 (Alprostidil). On examination, she had microcephaly, periorbital puffiness, a long philtrum, a broad nasal bridge and retrognathia, up slanting palpebral fissures, widely spaced nipples, a sacral dimple and right upper limb postaxial polydactyly. Postnatal echocardiography confirmed a large ostium secundum atrial septal defect with left to right shunt, right ventricle hypoplasia, pulmonary atresia with an intact septum and a large vertical patent ductus arteriosus. Ophthalmological examination showed a bilateral chorioretinal coloboma sparing disc and fovea. Karyotyping showed an extra small marker chromosome suggestive of the Cat eye syndrome. PMID:24842361

  16. Cat eye syndrome.

    PubMed

    Sharma, Deepak; Murki, Srinivas; Pratap, Tejo; Vasikarla, Madhavi

    2014-05-19

    A full-term female baby, a product of non-consanguineous marriage, was born at 37 weeks of gestation with a birth weight of 2.08 kg. Antenatal scan at 31 weeks revealed complex congenital heart disease with a hypoplastic right ventricle, pulmonary atresia and an intact septum. Immediately after birth, the infant was shifted to the nursery and was started on intravenous fluids and infusion prostaglandin E1 (Alprostidil). On examination, she had microcephaly, periorbital puffiness, a long philtrum, a broad nasal bridge and retrognathia, up slanting palpebral fissures, widely spaced nipples, a sacral dimple and right upper limb postaxial polydactyly. Postnatal echocardiography confirmed a large ostium secundum atrial septal defect with left to right shunt, right ventricle hypoplasia, pulmonary atresia with an intact septum and a large vertical patent ductus arteriosus. Ophthalmological examination showed a bilateral chorioretinal coloboma sparing disc and fovea. Karyotyping showed an extra small marker chromosome suggestive of the Cat eye syndrome.

  17. Crossing turbulent boundaries: interfacial flux in environmental flows.

    PubMed

    Grant, Stanley B; Marusic, Ivan

    2011-09-01

    Advances in the visualization and prediction of turbulence are shedding new light on mass transfer in the turbulent boundary layer. These discoveries have important implications for many topics in environmental science and engineering, from the transport of earth-warming CO2 across the sea-air interface, to nutrient processing and sediment erosion in rivers, lakes, and the ocean, to pollutant removal in water and wastewater treatment systems. In this article we outline current understanding of turbulent boundary layer flows, with particular focus on coherent turbulence and its impact on mass transport across the sediment-water interface in marine and freshwater systems.

  18. An overview of the CATS level 1 processing algorithms and data products

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; McGill, M. J.; Palm, S. P.; Hlavka, D. L.; Selmer, P. A.; Nowottnick, E. P.; Vaughan, M. A.; Rodier, S. D.; Hart, W. D.

    2016-05-01

    The Cloud-Aerosol Transport System (CATS) is an elastic backscatter lidar that was launched on 10 January 2015 to the International Space Station (ISS). CATS provides both space-based technology demonstrations for future Earth Science missions and operational science measurements. This paper outlines the CATS Level 1 data products and processing algorithms. Initial results and validation data demonstrate the ability to accurately detect optically thin atmospheric layers with 1064 nm nighttime backscatter as low as 5.0E-5 km-1 sr-1. This sensitivity, along with the orbital characteristics of the ISS, enables the use of CATS data for cloud and aerosol climate studies. The near-real-time downlinking and processing of CATS data are unprecedented capabilities and provide data that have applications such as forecasting of volcanic plume transport for aviation safety and aerosol vertical structure that will improve air quality health alerts globally.

  19. Ignition transition in turbulent premixed combustion

    SciTech Connect

    Shy, S.S.; Liu, C.C.; Shih, W.T.

    2010-02-15

    Recently, Shy and his co-workers reported a turbulent ignition transition based on measurements of minimum ignition energies (MIE) of lean premixed turbulent methane combustion in a centrally-ignited, fan-stirred cruciform burner capable of generating intense isotropic turbulence. Using the same methodology, this paper presents new complete MIE data sets for stoichiometric and rich cases at three different equivalence ratios {phi} = 1.0, 1.2 and 1.3, each covering a wide range of a turbulent Karlovitz number (Ka) indicating a time ratio between chemical reaction and turbulence. Thus, ignition transition in premixed turbulent combustion depending on both Ka and {phi} can be identified for the first time. It is found that there are two distinct modes on ignition in randomly stirred methane-air mixtures (ignition transition) separated by a critical Ka where values of Ka{sub c} {approx} 8-26 depending on {phi} with the minimum Ka{sub c} occurring near {phi} = 1. For Ka < Ka{sub c}, MIE increases gradually with Ka, flame kernel formation is similar to laminar ignition remaining a torus, and 2D laser tomography images of subsequent outwardly-propagating turbulent flames show sharp fronts. For Ka > Ka{sub c}, MIE increases abruptly with Ka, flame kernel is disrupted, and subsequent randomly-propagating turbulent flames reveal distributed-like fronts. Moreover, we introduce a reaction zone Peclet number (P{sub RZ}) indicating the diffusivity ratio between turbulence and chemical reaction, such that the aforementioned very scattering MIE data depending on Ka and {phi} can be collapsed into a single curve having two drastically different increasing slopes with P{sub RZ} which are separated by a critical P{sub RZ} {approx} 4.5 showing ignition transition. Finally, a physical model is proposed to explain these results. (author)

  20. Survival of a feline isolate of Tritrichomonas foetus in water, cat urine, cat food and cat litter.

    PubMed

    Rosypal, Alexa C; Ripley, Allyson; Stockdale Walden, Heather D; Blagburn, Byron L; Grant, David C; Lindsay, David S

    2012-04-30

    Feline intestinal trichomoniasis caused by Tritrichomonas foetus is associated with large bowel diarrhea in cats from many parts of the world. It has long been recognized as an economically important sexually transmitted disease that causes early abortion in cattle. Isolates of T. foetus from cattle are infectious for the large intestine of cats and isolates of T. foetus from cats are infectious for the reproductive system of cattle. The parasite is maintained by fecal-oral transmission in cats. The present study was conducted to examine the survival of a feline isolate of T. foetus, AUTf-12, under various conditions that are relevant to fecal-oral transmission in cats. Trophozoites were grown in TYM medium and then exposed to water, cat urine, dry cat food, canned cat food, clumping cat litter, or filter paper for various lengths of time and then re-cultured in TYM medium. Trophozoites survived exposure to distilled or tap water for 30 but not 60 min, while they survived for at least 180 min in urine. Trophozoites survived for 30 min on dry cat food but survived for 120-180 min in canned cat food. No survival of trophozoites was observed on cat litter but trophozoites survived for 15 min when placed on filter paper. Our results indicate that T. foetus can survive and be potentially infectious in water, urine, dry cat food and canned cat food.

  1. Investigation of heat and momentum transport in turbulent flows via numerical simulations

    NASA Technical Reports Server (NTRS)

    Kim, John

    1988-01-01

    Turbulent transport of heat is studied by examining the flow fields obtained from a direct simulation of a turbulent channel flow. The turbulence structures associated with the velocity and scalar fields are presented using air (Pr = 0.71) as the medium. A comparison is made between the wall-layer structures identified by the temperature field and the structures found in the velocity field. Consideration is also given to the role of the organized turbulence structures in scalar transport.

  2. The Cat's Eye Nebula

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This NASA Hubble Space Telescope image shows one of the most complex planetary nebulae ever seen, NGC 6543, nicknamed the 'Cat's Eye Nebula.' Hubble reveals surprisingly intricate structures including concentric gas shells, jets of high-speed gas and unusual shock-induced knots of gas. Estimated to be 1,000 years old, the nebula is a visual 'fossil record' of the dynamics and late evolution of a dying star. A preliminary interpretation suggests that the star might be a double-star system. The suspected companion star also might be responsible for a pair of high-speed jets of gas that lie at right angles to this equatorial ring. If the companion were pulling in material from a neighboring star, jets escaping along the companion's rotation axis could be produced. These jets would explain several puzzling features along the periphery of the gas lobes. Like a stream of water hitting a sand pile, the jets compress gas ahead of them, creating the 'curlicue' features and bright arcs near the outer edge of the lobes. The twin jets are now pointing in different directions than these features. This suggests the jets are wobbling, or precessing, and turning on and off episodically. This color picture, taken with the Wide Field Planetary Camera-2, is a composite of three images taken at different wavelengths. (red, hydrogen-alpha; blue, neutral oxygen, 6300 angstroms; green, ionized nitrogen, 6584 angstroms). The image was taken on September 18, 1994. NGC 6543 is 3,000 light- years away in the northern constellation Draco. The term planetary nebula is a misnomer; dying stars create these cocoons when they lose outer layers of gas. The process has nothing to do with planet formation, which is predicted to happen early in a star's life.

  3. Cat Ownership Perception and Caretaking Explored in an Internet Survey of People Associated with Cats.

    PubMed

    Zito, Sarah; Vankan, Dianne; Bennett, Pauleen; Paterson, Mandy; Phillips, Clive J C

    2015-01-01

    People who feed cats that they do not perceive they own (sometimes called semi-owners) are thought to make a considerable contribution to unwanted cat numbers because the cats they support are generally not sterilized. Understanding people's perception of cat ownership and the psychology underlying cat semi-ownership could inform approaches to mitigate the negative effects of cat semi-ownership. The primary aims of this study were to investigate cat ownership perception and to examine its association with human-cat interactions and caretaking behaviours. A secondary aim was to evaluate a definition of cat semi-ownership (including an association time of ≥1 month and frequent feeding), revised from a previous definition proposed in the literature to distinguish cat semi-ownership from casual interactions with unowned cats. Cat owners and semi-owners displayed similar types of interactions and caretaking behaviours. Nevertheless, caretaking behaviours were more commonly displayed towards owned cats than semi-owned cats, and semi-owned cats were more likely to have produced kittens (p<0.01). All interactions and caretaking behaviours were more likely to be displayed towards cats in semi-ownership relationships compared to casual interaction relationships. Determinants of cat ownership perception were identified (p<0.05) and included association time, attachment, perceived cat friendliness and health, and feelings about unowned cats, including the acceptability of feeding unowned cats. Encouraging semi-owners to have the cats they care for sterilized may assist in reducing the number of unwanted kittens and could be a valuable alternative to trying to prevent semi-ownership entirely. Highly accessible semi-owner "gatekeepers" could help to deliver education messages and facilitate the provision of cat sterilization services to semi-owners. This research enabled semi-ownership to be distinguished from casual interaction relationships and can assist welfare and

  4. Large Eddy Simulations of Severe Convection Induced Turbulence

    NASA Technical Reports Server (NTRS)

    Ahmad, Nash'at; Proctor, Fred

    2011-01-01

    Convective storms can pose a serious risk to aviation operations since they are often accompanied by turbulence, heavy rain, hail, icing, lightning, strong winds, and poor visibility. They can cause major delays in air traffic due to the re-routing of flights, and by disrupting operations at the airports in the vicinity of the storm system. In this study, the Terminal Area Simulation System is used to simulate five different convective events ranging from a mesoscale convective complex to isolated storms. The occurrence of convection induced turbulence is analyzed from these simulations. The validation of model results with the radar data and other observations is reported and an aircraft-centric turbulence hazard metric calculated for each case is discussed. The turbulence analysis showed that large pockets of significant turbulence hazard can be found in regions of low radar reflectivity. Moderate and severe turbulence was often found in building cumulus turrets and overshooting tops.

  5. DNS of the effects of thermal stratication and turbulent mixing on H2/air ignition in a constant volume, and comparison with the multi-zone model.

    SciTech Connect

    Sankaran, Ramanan; Chen, Jacqueline H.; Hawkes, Evatt R.; Im, Hong G.

    2005-01-01

    The influence of thermal stratification on auto-ignition at constant volume and high pressure is studied by Direct Numerical Simulation (DNS) with complex H{sub 2}/air chemistry with a view to providing better understanding of combustion processes in homogeneous charge compression ignition engines. In particular the dependence of overall ignition progress on initial mixture conditions is determined. The propagation speed of ignition fronts that emanate from 'hot spots' given by a temperature spectrum is monitored by using the displacement velocity of a scalar that tracks the location of maximum heat release. The evolution of the front velocity is compared for different initial temperature distributions and the role of scalar dissipation of heat and mass is identified. It is observed that both deagrative as well as spontaneous ignition front propagation occur depending upon the local temperature gradient. It is found that the ratio of the instantaneous front speed to the deflagrative speed is a good measure of the local mode of propagation. This is verified by examining the energy and species balances. A parametric study in the amplitudes of the initial temperature fluctuation is performed and shows that this parameter has a significant influence on the observed combustion mode. Higher levels of stratification lead to more front-like structures. Predictions of the multi-zone model are presented and explained using the diagnostics developed.

  6. Introduction to quantum turbulence

    PubMed Central

    Barenghi, Carlo F.; Skrbek, Ladislav; Sreenivasan, Katepalli R.

    2014-01-01

    The term quantum turbulence denotes the turbulent motion of quantum fluids, systems such as superfluid helium and atomic Bose–Einstein condensates, which are characterized by quantized vorticity, superfluidity, and, at finite temperatures, two-fluid behavior. This article introduces their basic properties, describes types and regimes of turbulence that have been observed, and highlights similarities and differences between quantum turbulence and classical turbulence in ordinary fluids. Our aim is also to link together the articles of this special issue and to provide a perspective of the future development of a subject that contains aspects of fluid mechanics, atomic physics, condensed matter, and low-temperature physics. PMID:24704870

  7. Modeling Compressed Turbulence

    SciTech Connect

    Israel, Daniel M.

    2012-07-13

    From ICE to ICF, the effect of mean compression or expansion is important for predicting the state of the turbulence. When developing combustion models, we would like to know the mix state of the reacting species. This involves density and concentration fluctuations. To date, research has focused on the effect of compression on the turbulent kinetic energy. The current work provides constraints to help development and calibration for models of species mixing effects in compressed turbulence. The Cambon, et al., re-scaling has been extended to buoyancy driven turbulence, including the fluctuating density, concentration, and temperature equations. The new scalings give us helpful constraints for developing and validating RANS turbulence models.

  8. The HelCat basic plasma science device

    NASA Astrophysics Data System (ADS)

    Gilmore, M.; Lynn, A. G.; Desjardins, T. R.; Zhang, Y.; Watts, C.; Hsu, S. C.; Betts, S.; Kelly, R.; Schamiloglu, E.

    2015-01-01

    The Helicon-Cathode(HelCat) device is a medium-size linear experiment suitable for a wide range of basic plasma science experiments in areas such as electrostatic turbulence and transport, magnetic relaxation, and high power microwave (HPM)-plasma interactions. The HelCat device is based on dual plasma sources located at opposite ends of the 4 m long vacuum chamber - an RF helicon source at one end and a thermionic cathode at the other. Thirteen coils provide an axial magnetic field B >= 0.220 T that can be configured individually to give various magnetic configurations (e.g. solenoid, mirror, cusp). Additional plasma sources, such as a compact coaxial plasma gun, are also utilized in some experiments, and can be located either along the chamber for perpendicular (to the background magnetic field) plasma injection, or at one of the ends for parallel injection. Using the multiple plasma sources, a wide range of plasma parameters can be obtained. Here, the HelCat device is described in detail and some examples of results from previous and ongoing experiments are given. Additionally, examples of planned experiments and device modifications are also discussed.

  9. Phenotypes and echocardiographic characteristics of a European population of domestic shorthair cats with idiopathic hypertrophic cardiomyopathy.

    PubMed

    Brizard, D; Amberger, C; Hartnack, S; Doherr, M; Lombard, C

    2009-11-01

    111 Domestic Shorthair cats with idiopathic hypertrophic cardiomyopathy were reviewed retrospectively. Two-dimensional echocardiography was used to classify cases in 6 established phenotypes. Hypertrophy was diffuse in 61 % of cats and involved major portions of the ventricular septum and the left ventricular free wall (phenotype D). In the remaining cats, distribution of hypertrophy was more segmental and was identified on the papillary muscles exclusively (phenotype A, 6 %), on the anterior and basal portion of the ventricular septum (phenotype B, 12 %), on the entire septum (phenotype C, 14 %), or on the left ventricular free wall (phenotype E, 7 %). Echocardiographic characteristics and clinical findings were determined for each phenotype to study the correlation between distribution of hypertrophy and clinical implications. 31 cats demonstrated systolic anterior motion of the mitral valve, 75 % of them belonged to phenotype C of hypertrophy. Left ventricular-outflow turbulences were identified more frequently with patterns of hypertrophy involving the ventricular septum (65.5 %), while prevalence of mitral regurgitation was higher when hypertrophy included the papillary muscles (phenotypes A and E, 85 % and 87 %, respectively). Left atrial dilatation occurred more frequently when hypertrophy was diffuse or confined to the left ventricular free wall (61 % of cats with phenotype D or E) rather than to the ventricular septum (31 % of cats with phenotype B or C).

  10. Turbulent Spots Inside the Turbulent Boundary Layer

    NASA Astrophysics Data System (ADS)

    Skarda, Jinhie; Wu, Xiaohua; Moin, Parviz; Lozano-Duran, Adrian; Wallace, James; Hickey, Jean-Pierre

    2016-11-01

    We present evidence that the buffer region of the canonical turbulent boundary layer is populated by locally generated turbulent spots, which cause strong indentations on the near-wall low-momentum streaks. This evidence is obtained from a spatially-developing direct numerical simulation carrying the inlet Blasius boundary layer through a bypass transition to the turbulent boundary layer state over a moderate Reynolds number range. The turbulent spots are structurally analogous to their transitional counter-parts but without any direct causality connection. High-pass filtered time-history records are used to calculate the period of turbulent spot detection and this period is compared to the boundary layer bursting period reported in hot-wire experiments. The sensitivity of the results to parameters such as the high pass filter frequency and the amplitude discriminator level is examined. The characteristics of these turbulent spots are also quantified using a spatial connectivity based conditional sampling technique. This evidence seems to be at odds with the notion that the buffer region is dominated by quasi-streamwise vortices, and contributes to the potential unification of the studies on near-wall turbulent boundary layer dynamics.

  11. Snowflakes as inertial particles in turbulence

    NASA Astrophysics Data System (ADS)

    Coletti, Filippo; Nemes, Andras; Dasari, Teja; Hong, Jiarong; Guala, Michele

    2016-11-01

    We report on the first direct measurements of trajectories and settling velocity of snow particles in the atmospheric surface layer. During a nocturnal snowfall we deploy an imaging system consisting of a searchlight and high speed cameras to illuminate and track thousands of snowflakes over a 7 m by 4 m vertical plane. We simultaneously characterize their shape and size using digital holography, while recording the air turbulence properties via sonic anemometry. We show that, in the meteorological conditions in object, the snowflake motion exhibits hallmark features identified by fundamental studies of particle-laden turbulence in both the Lagrangian and the Eulerian framework. The acceleration distribution displays stretched exponential tails, and by comparing with previous laboratory and computational studies we infer the Stokes number and aerodynamic response time of the snowflakes. The fall speed is found to be much greater than the expected value in still air, indicating that turbulence enhances settling according to the preferential sweeping mechanism. These observations demonstrate the major role of turbulence in determining the snow fall speed, and create the basis for leveraging results from particle-laden turbulence research towards improved snow precipitation models.

  12. Impulsively started incompressible turbulent jet

    SciTech Connect

    Witze, P O

    1980-10-01

    Hot-film anemometer measurements are presented for the centerline velocity of a suddenly started jet of air. The tip penetration of the jet is shown to be proportional to the square-root of time. A theoretical model is developed that assumes the transient jet can be characterized as a spherical vortex interacting with a steady-state jet. The model demonstrates that the ratio of nozzle radius to jet velocity defines a time constant that uniquely characterizes the behavior and similarity of impulsively started incompressible turbulent jets.

  13. Turbulence, Turbulence Control, and Drag Reduction.

    DTIC Science & Technology

    1987-08-01

    Onsager (1945) and Weizs~cker (1948). has made remarkable strides in advancing our understanding of turbulent flows. It is this description of turbulent...tujrbuilce Inl thle lar to thle Intermiittenit trans’ition to turbulence lus.t ,iedipen itlik. N\\N.tern onI the other. O pen0 * ~ ~ h 1 ~ kdinition10 po...Some Studies of Non-Simple Pipe Flows K R SREENIVASAN 2.AR’ .\\ variety o phenooena occrs ’.5’, ,sTecla’., f we stray,’ away from straight circ- lar i es a

  14. Laser beam propagation in atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Murty, S. S. R.

    1979-01-01

    The optical effects of atmospheric turbulence on the propagation of low power laser beams are reviewed in this paper. The optical effects are produced by the temperature fluctuations which result in fluctuations of the refractive index of air. The commonly-used models of index-of-refraction fluctuations are presented. Laser beams experience fluctuations of beam size, beam position, and intensity distribution within the beam due to refractive turbulence. Some of the observed effects are qualitatively explained by treating the turbulent atmosphere as a collection of moving gaseous lenses of various sizes. Analytical results and experimental verifications of the variance, covariance and probability distribution of intensity fluctuations in weak turbulence are presented. For stronger turbulence, a saturation of the optical scintillations is observed. The saturation of scintillations involves a progressive break-up of the beam into multiple patches; the beam loses some of its lateral coherence. Heterodyne systems operating in a turbulent atmosphere experience a loss of heterodyne signal due to the destruction of coherence.

  15. PDF modeling of turbulence-radiation interactions

    SciTech Connect

    Mazumder, S.; Modest, M.F.

    1997-07-01

    The interactions between turbulence and radiation, although acknowledged and qualitatively understood over the last several decades, are extremely difficult to model. Traditional Eulerian turbulence models are incapable of addressing the closure problem for any realistic reactive flow situation, because of the large number of unknown turbulent moments that need to be modeled. A novel approach, based on the velocity-composition joint probability density function (PDF) method, is presented. This approach is Lagrangian in nature and provides an elegant and feasible alternative to turbulence closure. A mixed Monte Carlo/finite-volume technique is used to simulate a bluff-body-stabilized methane-air diffusion flame in a two-dimensional planar recirculating combustor, and enables treatment of turbulence in recirculating flows, finite-rate chemistry, and multiple-band radiation calculations within the CPU limitations of a standard single-processor workstation. Results demonstrate the role of radiation and turbulence-radiation interactions in altering the overall flame structure, the wall heat loads, and the overall heat emission by the flame at various Reynolds numbers and equivalence ratios.

  16. Geometrical Monte Carlo simulation of atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Yuksel, Demet; Yuksel, Heba

    2013-09-01

    Atmospheric turbulence has a significant impact on the quality of a laser beam propagating through the atmosphere over long distances. Turbulence causes intensity scintillation and beam wander from propagation through turbulent eddies of varying sizes and refractive index. This can severely impair the operation of target designation and Free-Space Optical (FSO) communications systems. In addition, experimenting on an FSO communication system is rather tedious and difficult. The interferences of plentiful elements affect the result and cause the experimental outcomes to have bigger error variance margins than they are supposed to have. Especially when we go into the stronger turbulence regimes the simulation and analysis of the turbulence induced beams require delicate attention. We propose a new geometrical model to assess the phase shift of a laser beam propagating through turbulence. The atmosphere along the laser beam propagation path will be modeled as a spatial distribution of spherical bubbles with refractive index discontinuity calculated from a Gaussian distribution with the mean value being the index of air. For each statistical representation of the atmosphere, the path of rays will be analyzed using geometrical optics. These Monte Carlo techniques will assess the phase shift as a summation of the phases that arrive at the same point at the receiver. Accordingly, there would be dark and bright spots at the receiver that give an idea regarding the intensity pattern without having to solve the wave equation. The Monte Carlo analysis will be compared with the predictions of wave theory.

  17. Effects of submesoscale turbulence on ocean tracers

    NASA Astrophysics Data System (ADS)

    Smith, Katherine M.; Hamlington, Peter E.; Fox-Kemper, Baylor

    2016-01-01

    Ocean tracers such as carbon dioxide, nutrients, plankton, and oil advect, diffuse, and react primarily in the oceanic mixed layer where air-sea gas exchange occurs and light is plentiful for photosynthesis. There can be substantial heterogeneity in the spatial distributions of these tracers due to turbulent stirring, particularly in the submesoscale range where partly geostrophic fronts and eddies and small-scale three-dimensional turbulence are simultaneously active. In this study, a large eddy simulation spanning horizontal scales from 20 km down to 5 m is used to examine the effects of multiscale turbulent mixing on nonreactive passive ocean tracers from interior and sea-surface sources. The simulation includes the effects of both wave-driven Langmuir turbulence and submesoscale eddies, and tracers with different initial and boundary conditions are examined in order to understand the respective impacts of small-scale and submesoscale motions on tracer transport. Tracer properties are characterized using spatial fields and statistics, multiscale fluxes, and spectra, and the results detail how tracer mixing depends on air-sea tracer flux rate, tracer release depth, and flow regime. Although vertical fluxes of buoyancy by submesoscale eddies compete with mixing by Langmuir turbulence, vertical fluxes of tracers are often dominated by Langmuir turbulence, particularly for tracers that are released near the mixed-layer base or that dissolve rapidly through the surface, even in regions with pronounced submesoscale activity. Early in the evolution of some tracers, negative eddy diffusivities occur co-located with regions of negative potential vorticity, suggesting that symmetric instabilities or other submesoscale phenomenon may act to oppose turbulent mixing.

  18. Four cats with fungal rhinitis.

    PubMed

    Whitney, Beth L; Broussard, John; Stefanacci, Joseph D

    2005-02-01

    Fungal rhinitis is uncommon in the cat and cases of nasal aspergillosis-penicilliosis have been rarely reported. Signs of fungal rhinitis include epistaxis, sneezing, mucopurulent nasal discharge and exophthalmos. Brachycephalic feline breeds seem to be at increased risk for development of nasal aspergillosis-penicilliosis. Computed tomography (CT) imaging and rhinoscopy are useful in assessing the extent of the disease and in obtaining diagnostic samples. Fungal culture may lead to false negative or positive results and must be used in conjunction with other diagnostic tests. Serological testing was not useful in two cats tested. The cats in this study were treated with oral itraconazole therapy. When itraconazole therapy was discontinued prematurely, clinical signs recurred. Hepatotoxicosis is a possible sequel to itraconazole therapy.

  19. Grooming and control of fleas in cats.

    PubMed

    Eckstein; Hart

    2000-05-10

    Oral grooming is common in cats, as in rodent and bovid species where grooming has been shown to be effective in removing lice and ticks. In Experiment 1, we examined the effectiveness of oral grooming in removing fleas which are the main ectoparasite of cats. Elizabethan collars (E-collars) which prevented grooming were fitted on nine cats in a flea-infested household and 3 weeks later, flea numbers on these cats were compared with nine control cats in the same household. Flea numbers dropped in the control cats reflecting an apparent drop in adult fleas in the environment, but in the E-collar cats, flea numbers did not drop, and were about twice as numerous as in control cats. The significantly greater number of fleas on the E-collar cats was attributed to their inability to groom off fleas. In Experiment 2, videotaping of nine different cats from the flea-infested household revealed that these cats groomed at about twice the rate of 10 similarly videotaped control cats from a flea-free colony. These results reveal that flea exposure can increase grooming rate in cats and that grooming is effective in removing fleas.

  20. The paradox of Schrodinger's cat

    NASA Astrophysics Data System (ADS)

    Villars, C. N.

    1986-07-01

    Erwin Schrodinger first described the thought-experiment which has since become known as 'the paradox of Schrodinger's cat' 51 years ago. In recent years, popular accounts of quantum mechanics have tended to adopt one or other of the philosophically most extreme solutions to this paradox, i.e. the consciousness hypothesis or the many worlds interpretation. The author attempts to redress the balance by describing what he takes to be the orthodox solution to the paradox which explains the paradox, without recourse to such counterintuitive notions as a cat simultaneously dead and alive or a universe continually splitting into multiple worlds, as being due to a misapplication of the quantum formalism.

  1. Osteolysis in cat-scratch fever

    SciTech Connect

    Johnson, J.F.; Lehman, R.M.; Shiels, W.E.; Blaney, S.M.

    1985-08-01

    The osteolysis associated with cat-scratch fever resembles more ominous conditions. The combination of osteolysis and unilateral regional adenopathy in a child or adolescent should suggest cat-scratch disease. Bone scans and CT verified the diagnosis.

  2. Fungal rhinitis and sinusitis in three cats.

    PubMed

    Tomsa, Kamil; Glaus, Tony M; Zimmer, Cindy; Greene, Craig E

    2003-05-15

    Localized infection of the nasal or paranasal cavities caused by Aspergillus spp or Penicillium spp was diagnosed in 3 cats. Clinical signs included chronic mucopurulent nasal discharge, epistaxis, and mandibular lymphadenopathy. Rhinoscopic and diagnostic imaging findings were compatible with severe inflammation of the nasal mucosa and destruction of the turbinates. Fungal plaques were observed rhinoscopically in 2 cats, and histologic examination of biopsy specimens revealed fungal colonies with surrounding inflammatory infiltrates in all 3. Results of fungal culture were negative for all 3 cats. Results of serum immunoelectrophoresis for antibodies against Aspergillus spp were positive in 2 cats. Treatment with itraconazole was effective in controlling clinical signs in 1 cat, but hepatotoxicosis developed. A single intranasal infusion of clotrimazole subsequently led to long-term resolution of clinical signs in this cat. Localized aspergillosis-penicilliosis is clinically indistinguishable from other pathologic conditions of the nasal and paranasal cavities in cats and should be considered when examining cats with chronic nasal discharge.

  3. Isolation of Malassezia furfur from a Cat

    PubMed Central

    Crespo, M. J.; Abarca, M. L.; Cabañes, F. J.

    1999-01-01

    During a survey of the occurrence of Malassezia species in the external ear canals of cats without otitis externa, Malassezia furfur was isolated. This is the first report of the isolation of M. furfur from cats. PMID:10203525

  4. Review of wave-turbulence interactions in the stable atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Sun, Jielun; Nappo, Carmen J.; Mahrt, Larry; Belušić, Danijel; Grisogono, Branko; Stauffer, David R.; Pulido, Manuel; Staquet, Chantal; Jiang, Qingfang; Pouquet, Annick; Yagüe, Carlos; Galperin, Boris; Smith, Ronald B.; Finnigan, John J.; Mayor, Shane D.; Svensson, Gunilla; Grachev, Andrey A.; Neff, William D.

    2015-09-01

    Flow in a stably stratified environment is characterized by anisotropic and intermittent turbulence and wavelike motions of varying amplitudes and periods. Understanding turbulence intermittency and wave-turbulence interactions in a stably stratified flow remains a challenging issue in geosciences including planetary atmospheres and oceans. The stable atmospheric boundary layer (SABL) commonly occurs when the ground surface is cooled by longwave radiation emission such as at night over land surfaces, or even daytime over snow and ice surfaces, and when warm air is advected over cold surfaces. Intermittent turbulence intensification in the SABL impacts human activities and weather variability, yet it cannot be generated in state-of-the-art numerical forecast models. This failure is mainly due to a lack of understanding of the physical mechanisms for seemingly random turbulence generation in a stably stratified flow, in which wave-turbulence interaction is a potential mechanism for turbulence intermittency. A workshop on wave-turbulence interactions in the SABL addressed the current understanding and challenges of wave-turbulence interactions and the role of wavelike motions in contributing to anisotropic and intermittent turbulence from the perspectives of theory, observations, and numerical parameterization. There have been a number of reviews on waves, and a few on turbulence in stably stratified flows, but not much on wave-turbulence interactions. This review focuses on the nocturnal SABL; however, the discussions here on intermittent turbulence and wave-turbulence interactions in stably stratified flows underscore important issues in stably stratified geophysical dynamics in general.

  5. Turbulence generation by waves

    SciTech Connect

    Kaftori, D.; Nan, X.S.; Banerjee, S.

    1995-12-31

    The interaction between two-dimensional mechanically generated waves, and a turbulent stream was investigated experimentally in a horizontal channel, using a 3-D LDA synchronized with a surface position measuring device and a micro-bubble tracers flow visualization with high speed video. Results show that although the wave induced orbital motion reached all the way to the wall, the characteristics of the turbulence wall structures and the turbulence intensity close to the wall were not altered. Nor was the streaky nature of the wall layer. On the other hand, the mean velocity profile became more uniform and the mean friction velocity was increased. Close to the free surface, the turbulence intensity was substantially increased as well. Even in predominantly laminar flows, the introduction of 2-D waves causes three dimensional turbulence. The turbulence enhancement is found to be proportional to the wave strength.

  6. One-dimensional turbulence

    SciTech Connect

    Kerstein, A.R.

    1996-12-31

    One-Dimensional Turbulence is a new turbulence modeling strategy involving an unsteady simulation implemented in one spatial dimension. In one dimension, fine scale viscous and molecular-diffusive processes can be resolved affordably in simulations at high turbulence intensity. The mechanistic distinction between advective and molecular processes is thereby preserved, in contrast to turbulence models presently employed. A stochastic process consisting of mapping {open_quote}events{close_quote} applied to a one-dimensional velocity profile represents turbulent advection. The local event rate for given eddy size is proportional to the velocity difference across the eddy. These properties cause an imposed shear to induce an eddy cascade analogous in many respects to the eddy cascade in turbulent flow. Many scaling and fluctuation properties of self-preserving flows, and of passive scalars introduced into these flows, are reproduced.

  7. [Lameness of the hindlimbs of the cat].

    PubMed

    Grevel, V

    1989-08-01

    About six to seven per cent of cats presented at the clinic show neurological signs. The largest group consists of traumatized cats. A complete neurological examination is essential for localizing the lesion and establishing a prognosis. Differential diagnosis for paraparesis/paraplegia of pelvic limbs in cats are discussed. Cats are demonstrated which had spinal cord trauma, disc protrusion, aortic thromboembolism and lumbosacral stenosis and the importance of the evaluation of x-rays, cerebrospinal fluid examination and myelography is stressed.

  8. Cryosurgery of eosinophilic ulcers in cats.

    PubMed

    Willemse, A; Lubberink, A A

    1978-10-15

    The use of cryosurgery in treatment of eosinophilic granuloma in cats is described. Satisfactory results were obtained in 14 of 19 cats and 4 of the 5 cats which did not respond favorably, had multiple lesions. The simplicity of the technique and the rapidity of healing make cryosurgery a useful alternative to previous methods of treatment.

  9. Getting a CAT Scan (For Kids)

    MedlinePlus Videos and Cool Tools

    ... dientes Video: Getting an X-ray Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that means ...

  10. Toxoplasmosis: An Important Message for Cat Owners

    MedlinePlus

    ... a s t is O : wAnneIrmsportant What role do cats play in the spread of toxoplasmosis? Cats get Toxoplasma infection by eating infected rodents, birds ... animals, or anything contaminated with feces from another cat that is shedding the microscopic parasite in its ...

  11. Dipylidium (Dog and Cat Flea Tapeworm) FAQs

    MedlinePlus

    ... the most common kind of tapeworm dogs and cats get? The most common tapeworm of dogs and cats in the United States is called Dipylidium caninum . ... infected with a tapeworm larvae. A dog or cat may swallow a flea while self-grooming. Once ...

  12. CATS Data and Information Page

    Atmospheric Science Data Center

    2017-01-10

    ... of atmospheric aerosols and clouds from the International Space Station (ISS).   CATS will provide vertical profiles at three ... (day-to-night) changes in cloud and aerosol effects from space by observing the same spot on Earth at different times each day. ...

  13. Lymphoplasmacytic gingivitis in a cat

    PubMed Central

    2005-01-01

    Abstract A 12-year-old male neutered short haired cat was presented due to difficulty eating and pawing at the face. Examination revealed severe gingivitis and stomatitis throughout the oral cavity. Gingival biopsy provided a diagnosis of lymphoplasmacytic stomatitis. Extraction of all premolars and molars resulted in elimination of all clinical signs. PMID:16048015

  14. A strange cat in Dublin

    NASA Astrophysics Data System (ADS)

    O'Raifeartaigh, Cormac

    2012-11-01

    Not many life stories in physics involve Nazis, illicit sex, a strange cat and the genetic code. Thus, a new biography of the great Austrian physicist Erwin Schrödinger is always of interest, and with Erwin Schrödinger and the Quantum Revolution, veteran science writer John Gribbin does not disappoint.

  15. [Poxvirus infection in a cat].

    PubMed

    Ballauf, B; Linckh, S; Lechner, J

    1989-01-01

    For the first time, a poxvirus infection was diagnosed as an etiologic agent of dermal disease in a living domestic cat in Germany. A literature survey, the clinical symptoms of the infection and the diagnostic procedures are described. Poxvirus infections should be considered as a differential diagnosis in feline dermatologic problems.

  16. A CAT scan for cells

    SciTech Connect

    2009-01-01

    Recently, a team of scientists from Berkeley Lab, Stanford University, and the University of California, San Francisco used Berkeley Lab's National Center for X-ray Tomography to capture the changes that occur when Candida albicans is exposed to a new and promising antifungal therapy. http://newscenter.lbl.gov/feature-stories/2009/12/10/cat-scan-cells/

  17. Lessons from the Cheshire Cat

    ERIC Educational Resources Information Center

    Tinberg, Donna

    2012-01-01

    "If you don't know where you're going, any road will take you there." This oft-cited but not-quite-accurate quote is from the Lewis Carroll's classic children's tale, Alice in Wonderland. In Carroll's altered reality, the conversation between the disoriented Alice and the mysterious Cheshire Cat actually went like this: "Would you…

  18. Lymphoplasmacytic gingivitis in a cat.

    PubMed

    Baird, Kristin

    2005-06-01

    A 12-year-old male neutered short haired cat was presented due to difficulty eating and pawing at the face. Examination revealed severe gingivitis and stomatitis throughout the oral cavity. Gingival biopsy provided a diagnosis of lymphoplasmacytic stomatitis. Extraction of all premolars and molars resulted in elimination of all clinical signs.

  19. Assessing CAT Test Security Severity

    ERIC Educational Resources Information Center

    Yi, Qing; Zhang, Jinming; Chang, Hua-Hua

    2006-01-01

    In addition to its precision superiority over nonadaptive tests, another known advantage of computerized adaptive tests (CATs) is that they can be offered on a continuous basis. This is advantageous to examinees in terms of flexibility of test scheduling, as well as advantageous to schools and other testing centers in terms of both space and…

  20. Turbulence in astrophysics

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.

    1990-01-01

    Some of the astrophysical scenarios in which turbulence plays an important role are discussed in view of the comparative advantages of currently available models of turbulence phenomena; attention is given to a specific model that has undergone continuous refinement since 1985. The desideratum in this inquiry is a turbulence model which incorporates the best features of an a priori deterministic model, as well as a redundant set of results from full numerical simulations for a wide variety of turbulent flows; there should also be a simplification of the former, and an enlargement of the complexities of the latter.

  1. Tactical missile turbulence problems

    NASA Technical Reports Server (NTRS)

    Dickson, Richard E.

    1987-01-01

    Of particular interest is atmospheric turbulence in the atmospheric boundary layer, since this affects both the launch and terminal phase of flight, and the total flight for direct fire systems. Brief discussions are presented on rocket artillery boost wind problems, mean wind correction, turbulent boost wind correction, the Dynamically Aimed Free Flight Rocket (DAFFR) wind filter, the DAFFR test, and rocket wake turbulence problems. It is concluded that many of the turbulence problems of rockets and missiles are common to those of aircraft, such as structural loading and control system design. However, these problems have not been solved at this time.

  2. String Theory and Turbulence

    NASA Astrophysics Data System (ADS)

    Jejjala, Vishnu; Minic, Djordje; Ng, Y. Jack; Tze, Chia-Hsiung

    We propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. This string theory of turbulence should be understood in light of the AdS/CFT dictionary. Our argument is crucially based on the use of Migdal's loop variables and the self-consistent solutions of Migdal's loop equations for turbulence. In particular, there is an area law for turbulence in 2+1 dimensions related to the Kraichnan scaling.

  3. Experimental study of premixed flames in intense isotropic turbulence

    SciTech Connect

    Bedat, B.; Cheng, R.K.

    1994-04-01

    A methodology for investigating premixed turbulent flames propagating in intense isotropic turbulence has been developed. The burner uses a turbulence generator developed by Videto and Santavicca and the flame is stabilized by weak-swirl generated by air injectors. This set-up produces stable premixed turbulent flames under a wide range of mixture conditions and turbulence intensities. The experiments are designed to investigate systematically the changes in flame structures for conditions which can be classified as wrinkled laminar flames, corrugated flames and flames with distributed reaction zones. Laser Doppler anemometry and Rayleigh scattering techniques are used to determine the turbulence and scalar statistics. In the intense turbulence, the flames are found to produce very little changes in the mean and rams velocities. Their flame speed increase linearly with turbulence intensity as for wrinkled laminar flames. The Rayleigh scattering pdfs for flames within the distributed reaction zone regime are distinctly bimodal. The probabilities of the reacting states (i.e. contributions from within the reaction zone) is not higher than those of wrinkled laminar flame. These results show that there is no drastic changes in flame structures at Karlovitz number close to unity. This suggest that the Klimov-Williams criterion under-predicts the resilience of wrinkled flamelets to intense turbulence.

  4. A MODEL OF TURBULENT DIFFUSION FLAMES AND NITRIC OXIDE GENERATION

    EPA Science Inventory

    The report describes a new view of mixing and chemical reactions in turbulent fuel jets discharging into air. Review of available fundamental data from jet flames leads to the idea that mixing begins with a large scale, inviscid intertwining of entrained air and fuel throughout t...

  5. Audiogenic reflex seizures in cats

    PubMed Central

    Lowrie, Mark; Bessant, Claire; Harvey, Robert J; Sparkes, Andrew; Garosi, Laurent

    2015-01-01

    Objectives This study aimed to characterise feline audiogenic reflex seizures (FARS). Methods An online questionnaire was developed to capture information from owners with cats suffering from FARS. This was collated with the medical records from the primary veterinarian. Ninety-six cats were included. Results Myoclonic seizures were one of the cardinal signs of this syndrome (90/96), frequently occurring prior to generalised tonic–clonic seizures (GTCSs) in this population. Other features include a late onset (median 15 years) and absence seizures (6/96), with most seizures triggered by high-frequency sounds amid occasional spontaneous seizures (up to 20%). Half the population (48/96) had hearing impairment or were deaf. One-third of cats (35/96) had concurrent diseases, most likely reflecting the age distribution. Birmans were strongly represented (30/96). Levetiracetam gave good seizure control. The course of the epilepsy was non-progressive in the majority (68/96), with an improvement over time in some (23/96). Only 33/96 and 11/90 owners, respectively, felt the GTCSs and myoclonic seizures affected their cat’s quality of life (QoL). Despite this, many owners (50/96) reported a slow decline in their cat’s health, becoming less responsive (43/50), not jumping (41/50), becoming uncoordinated or weak in the pelvic limbs (24/50) and exhibiting dramatic weight loss (39/50). These signs were exclusively reported in cats experiencing seizures for >2 years, with 42/50 owners stating these signs affected their cat’s QoL. Conclusions and relevance In gathering data on audiogenic seizures in cats, we have identified a new epilepsy syndrome named FARS with a geriatric onset. Further studies are warranted to investigate potential genetic predispositions to this condition. PMID:25916687

  6. Idiopathic generalised tremor syndrome in two cats.

    PubMed

    Mauler, Daniela A; Van Soens, Iris; Bhatti, Sofie F; Cornelis, Ine; Martlé, Valentine A; Van Ham, Luc M

    2014-04-01

    Two male neutered domestic shorthair cats were evaluated for generalised tremors. On neurological examination both cats showed whole-body tremors, worsening with stress. A mainly cerebellar disorder was suspected. Blood examination, cerebrospinal fluid analysis and electrophysiological examination of both cats and magnetic resonance imaging of the brain in one cat were normal. Idiopathic generalised tremor syndrome (IGTS) was suspected owing to the exclusion of underlying causes and the clinical similarities with the syndrome in dogs. Treatment as recommended for dogs was initiated and resulted in improvement. This report describes the first cases of IGTS in cats.

  7. An experimental study of turbulent two-phase flow in hydraulic jumps and application of a triple decomposition technique

    NASA Astrophysics Data System (ADS)

    Wang, Hang; Felder, Stefan; Chanson, Hubert

    2014-07-01

    Intense turbulence develops in the two-phase flow region of hydraulic jump, with a broad range of turbulent length and time scales. Detailed air-water flow measurements using intrusive phase-detection probes enabled turbulence characterisation of the bubbly flow, although the phenomenon is not a truly random process because of the existence of low-frequency, pseudo-periodic fluctuating motion in the jump roller. This paper presents new measurements of turbulent properties in hydraulic jumps, including turbulence intensity, longitudinal and transverse integral length and time scales. The results characterised very high turbulent levels and reflected a combination of both fast and slow turbulent components. The respective contributions of the fast and slow motions were quantified using a triple decomposition technique. The decomposition of air-water detection signal revealed "true" turbulent characteristics linked with the fast, microscopic velocity turbulence of hydraulic jumps. The high-frequency turbulence intensities were between 0.5 and 1.5 close to the jump toe, and maximum integral turbulent length scales were found next to the bottom. Both decreased in the flow direction with longitudinal turbulence dissipation. The results highlighted the considerable influence of hydrodynamic instabilities of the flow on the turbulence characterisation. The successful application of triple decomposition technique provided the means for the true turbulence properties of hydraulic jumps.

  8. Relationship Between Vortex Meander and Ambient Turbulence

    NASA Technical Reports Server (NTRS)

    Rossow, Vernon J.; Hardy, Gordon H.; Meyn, Larry A.

    2006-01-01

    Efforts are currently underway to increase the capacity of airports by use of closely-spaced parallel runways. If such an objective is to be achieved safely and efficiently during both visual and instrument flight conditions, it will be necessary to develop more precise methods for the prediction of the motion and spread of the hazard posed by the lift-generated vortex-wakes of aircraft, and their uncertainties. The purpose of the present study is to relate the motion induced in vortex filaments by turbulence in the ambient flow field to the measured turbulence in the flow field. The problem came about when observations made in the two largest NASA wind tunnels indicated that extended exposure of vortex wakes to the turbulence in the wind tunnel air stream causes the centers of the vortices to meander about with time at a given downstream station where wake measurements are being made. Although such a behavior was expected, the turbulence level based on the maximum amplitude of meander was much less than the root-mean-squared value measured in the free-stream of the wind tunnel by use of hot-film anemometers. An analysis of the time-dependent motion of segments of vortex filaments as they interact with an eddy, indicates that the inertia of the filaments retards their motion enough in the early part of their travel to account for a large part of the difference in the two determinations of turbulence level. Migration of vortex filaments from one turbulent eddy to another (probably with a different orientation), is believed to account for the remainder of the difference. Methods that may possibly be developed for use in the measurement of the magnitude of the more intense eddies in turbulent flow fields and how they should be adjusted to predict vortex meander are then discussed.

  9. Market Assessment of Forward-Looking Turbulence Sensing Systems

    NASA Technical Reports Server (NTRS)

    Kauffmann, Paul

    2003-01-01

    This viewgraph presentation provides a cost benefit analysis of three next-generation forward-looking turbulence sensing systems: X band turbulence radar system for convective turbulence, LIDAR based turbulence systems to sense clear air turbulence and a combined hybrid system. Parameters for the cost benefit analysis were established using a business model which considered injury rates, cost of injuries, indirect costs, market penetration rate estimates and product success characteristics. Topics covered include: study approach, business case equations, data acquisition, benchmark analysis. Data interpretation from the cost benefit analysis is presented. The researchers conclude that the market potential for these products is based primarily on injury cost reduction and that X band radar systems have the greatest chance for commercial success.

  10. Evaporation of polydispersed droplets in a highly turbulent channel flow

    NASA Astrophysics Data System (ADS)

    Cochet, M.; Bazile, Rudy; Ferret, B.; Cazin, S.

    2009-09-01

    A model experiment for the study of evaporating turbulent two-phase flows is presented here. The study focuses on a situation where pre-atomized and dispersed droplets vaporize and mix in a heated turbulent flow. The test bench consists in a channel flow with characteristics of homogeneous and isotropic turbulence where fluctuations levels reach very high values (25% in the established zone). An ultrasonic atomizer allows the injection of a mist of small droplets of acetone in the carrier flow. The large range diameters ensure that every kind of droplet behavior with regards to turbulence is possible. Instantaneous concentration fields of the vaporized phase are extracted from fluorescent images (PLIF) of the two phase flow. The evolution of the mixing of the acetone vapor is analyzed for two different liquid mass loadings. Despite the high turbulence levels, concentration fluctuations remain significant, indicating that air and acetone vapor are not fully mixed far from the injector.

  11. Lumbosacral intervertebral disk disease in six cats.

    PubMed

    Harris, Jennipher E; Dhupa, Sarit

    2008-01-01

    Medical records of six cats diagnosed with lumbosacral intervertebral disk disease were reviewed. Clinical signs included reluctance to jump, low tail carriage, elimination outside the litter box, reluctance to ambulate, pelvic-limb paresis, urinary incontinence, and constipation. All cats had lumbosacral hyperpathia on palpation. Computed tomography in four cats revealed evidence of extradural spinal cord compression at the seventh lumbar (L(7)) to first sacral (S(1)) vertebral interspace. Compression was confirmed via myelography in three of these four cats, with confirmation in the fourth cat at the time of decompressive laminectomy. Each of the six cats underwent dorsal decompressive laminectomy at the L(7) to S(1) interspace. Postoperative clinical follow-up lasted 3 to 35 months, with most cats having excellent outcomes.

  12. General scale-dependent anisotropic turbulence and its impact on free space optical communication system performance.

    PubMed

    Toselli, Italo; Korotkova, Olga

    2015-06-01

    We generalize a recently introduced model for nonclassic turbulent spatial power spectrum involving anisotropy along two mutually orthogonal axes transverse to the direction of beam propagation by including two scale-dependent weighting factors for these directions. Such a turbulent model may be pertinent to atmospheric fluctuations in the refractive index in stratified regions well above the boundary layer and employed for air-air communication channels. When restricting ourselves to an unpolarized, coherent Gaussian beam and a weak turbulence regime, we examine the effects of such a turbulence type on the OOK FSO link performance by including the results on scintillation flux, probability of fade, SNR, and BERs.

  13. MHD turbulent processes

    NASA Technical Reports Server (NTRS)

    Montgomery, David

    1988-01-01

    Three areas of study in MHD turbulence are considered. These are the turbulent relaxation of the toroidal Z pinch, density fluctuations in MHD fluids, and MHD cellular automata. A Boolean computer game that updates a cellular representation in parallel and that has macroscopic averages converging to solutions of the two-dimensional MHD equations is discussed.

  14. NO concentration imaging in turbulent nonpremixed flames

    SciTech Connect

    Schefer, R.W.

    1993-12-01

    The importance of NO as a pollutant species is well known. An understanding of the formation characteristics of NO in turbulent hydrocarbon flames is important to both the desired reduction of pollutant emissions and the validation of proposed models for turbulent reacting flows. Of particular interest is the relationship between NO formation and the local flame zone, in which the fuel is oxidized and primary heat release occurs. Planar imaging of NO provides the multipoint statistics needed to relate NO formation to the both the flame zone and the local turbulence characteristics. Planar imaging of NO has been demonstrated in turbulent flames where NO was seeded into the flow at high concentrations (2000 ppm) to determine the gas temperature distribution. The NO concentrations in these experiments were significantly higher than those expected in typical hydrocarbon-air flames, which require a much lower detectability limit for NO measurements. An imaging technique based on laser-induced fluorescence with sufficient sensitivity to study the NO formation mechanism in the stabilization region of turbulent lifted-jet methane flames.

  15. Liquid infused surfaces in turbulent channel flow

    NASA Astrophysics Data System (ADS)

    Fu, Matthew; Stone, Howard; Smits, Alexander; Jacobi, Ian; Samaha, Mohamed; Wexler, Jason; Shang, Jessica; Rosenberg, Brian; Hellström, Leo; Fan, Yuyang; Wang, Karen; Lee, Kevin; Hultmark, Marcus

    2014-11-01

    A turbulent channel flow facility is used to measure the drag reduction capabilities and dynamic behavior of liquid-infused micro-patterned surfaces. Liquid infused surfaces have been proposed as a robust alternative to traditional air-cushion-based superhydrophobic surfaces. The mobile liquid lubricant creates a surface slip with the outer turbulent shear flow as well as an energetic sink to dampen turbulent fluctuations. Micro-manufactured surfaces can be mounted flush in the channel and exposed to turbulent flows. Two configurations are possible, both capable of producing laminar and turbulent flows. The first configuration allows detailed investigation of the infused liquid layer and the other allows well resolved pressure gradient measurements. Both of the configurations have high aspect ratios 15-45:1. Drag reduction for a variety of liquid-infused surface architectures is quantified by measuring pressure drop in the channel. Flow in the oil film is simultaneously visualized using fluorescent dye. Supported under ONR Grants N00014-12-1-0875 and N00014-12-1-0962 (program manager Ki-Han Kim).

  16. Elasto-inertial turbulence

    PubMed Central

    Samanta, Devranjan; Dubief, Yves; Holzner, Markus; Schäfer, Christof; Morozov, Alexander N.; Wagner, Christian; Hof, Björn

    2013-01-01

    Turbulence is ubiquitous in nature, yet even for the case of ordinary Newtonian fluids like water, our understanding of this phenomenon is limited. Many liquids of practical importance are more complicated (e.g., blood, polymer melts, paints), however; they exhibit elastic as well as viscous characteristics, and the relation between stress and strain is nonlinear. We demonstrate here for a model system of such complex fluids that at high shear rates, turbulence is not simply modified as previously believed but is suppressed and replaced by a different type of disordered motion, elasto-inertial turbulence. Elasto-inertial turbulence is found to occur at much lower Reynolds numbers than Newtonian turbulence, and the dynamical properties differ significantly. The friction scaling observed coincides with the so-called “maximum drag reduction” asymptote, which is exhibited by a wide range of viscoelastic fluids. PMID:23757498

  17. MHD turbulent mixing layers

    SciTech Connect

    Esquivel, A.; Lazarian, A.; Benjamin, R.A.; Cho, J.; Leitner, S.N.

    2005-09-28

    Turbulent mixing layers have been proposed to explain observations of line ratios of highly ionized elements in the interstellar medium. We present preliminary results of numerical simulations of turbulent mixing layers in a magnetized medium. We developed a MHD code with radiative cooling. The magnetic field is expected to be a controlling factor by suppressing instabilities that lead to the turbulent mixing. Our results suggest that the difference in turbulent mixing in the unmagnetized case as compared to the case of a weak magnetic field, {beta} = Pgas/Pmag {approx} 10, is insignificant. With a more thorough exploration of parameter space, this work will provide more reliable diagnostics of turbulent mixing layers than those available today.

  18. Combustion-turbulence interaction in the turbulent boundary layer over a hot surface

    SciTech Connect

    Ng, T.T.; Cheng, R.K.; Robben, F.; Talbot, L.

    1982-01-01

    The turbulence-combustion interaction in a reacting turbulent boundary layer over a heated flat plate was studied. Ethylene/air mixture with equivalence ratio of 0.35 was used. The free stream velocity was 10.5 m/s and the wall temperature was 1250/sup 0/K. Combustion structures visualization was provided by high-speed schlieren photographs. Fluid density statistics were deduced from Rayleigh scattering intensity measurements. A single-component laser Doppler velocimetry system was used to obtain mean and root-mean-square velocity distributions, the Reynolds stress, the streamwise and the cross-stream turbulent kinetic energy diffusion, and the production of turbulent kinetic energy by Reynolds stress. The combustion process was dominated by large-scale turbulent structures of the boundary layer. Combustion causes expansion of the boundary layer. No overall self-similarity is observed in either the velocity or the density profiles. Velocity fluctuations were increased in part of the boundary layer and the Reynolds stress was reduced. The turbulent kinetic energy diffusion pattern was changed significantly and a modification of the boundary layer assumption will be needed when dealing with this problem analytically. 11 figures, 1 table.

  19. The ``turbulent flame speed'' of wrinkled premixed flames

    NASA Astrophysics Data System (ADS)

    Matalon, Moshe; Creta, Francesco

    2012-11-01

    The determination of the turbulent flame speed is a central problem in combustion theory. Early studies by Damköhler and Shelkin resorted to geometrical and scaling arguments to deduce expressions for the turbulent flame speed and its dependence on turbulence intensity. A more rigorous approach was undertaken by Clavin and Williams who, based on a multi-scale asymptotic approach valid for weakly wrinkled flames, derived an expression that apart from a numerical factor recaptures the early result by Damköhler and Shelkin. The common denominator of the phenomenological and the more rigorous propositions is an increase in turbulent flame speed due solely to an increase in flame surface area. Various suggestions based on physical and/or experimental arguments have been also proposed, incorporating other functional parameters into the flame speed relation. The objective of this work is to extend the asymptotic results to a fully nonlinear regime that permits to systematically extract scaling laws for the turbulent flame speed that depend on turbulence intensity and scale, mixture composition and thermal expansion, flow conditions including effects of curvature and strain, and flame instabilities. To this end, we use a hybrid Navier-Stokes/front-capturing methodology, which consistently with the asymptotic model, treats the flame as a surface of density discontinuity separating burned and unburned gases. The present results are limited to positive Markstein length, corresponding to lean hydrocarbon-air or rich hydrogen-air mixtures, and to wrinkled flames of vanishingly small thickness, smaller that the smallest fluid scales. For simplicity we have considered here two-dimensional turbulence, which although lacks some features of real three-dimensional turbulence, is not detrimental when using the hydrodynamic model under consideration, because the turbulent flame retains its laminar structure and its interaction with turbulence is primarily advective/kinematic in

  20. Isolation of Tritrichomonas foetus from cats sampled at a cat clinic, cat shows and a humane society in southern Ontario.

    PubMed

    Hosein, Ansarah; Kruth, Stephen A; Pearl, David L; Richardson, Danielle; Maggs, Jocelyn C; Peach, Hillary A; Peregrine, Andrew S

    2013-08-01

    Tritrichomonas foetus is a protozoan parasite that has been associated with chronic diarrhea in cats. This study aimed to determine (i) the prevalence of T foetus shedding in cats from three different populations in southern Ontario, and (ii) associations between the presence of T foetus and potential cat management, health and demographic risk factors. A cross-sectional study was conducted involving 140 cats from a cat clinic in Guelph, 46 cats from a humane society in Guelph and 55 cats from two cat shows. Risk factor information was assessed through a questionnaire. The InPouch TF (feline) culture method was used to determine the presence of T foetus in all samples. Polymerase chain reaction was conducted on all samples positive by the InPouch TF, as well as 132 negative samples. The assays were interpreted in series and the prevalence of T foetus shedding and 95% confidence intervals (CI) were estimated at 0.7% (95% CI: 0.0-3.9%; n = 140) from the cat clinic, 0% (95% CI: 0.0-7.7%; n = 46) from the humane society and 23.6% (95% CI: 13.2-37.0%; n = 55) from the cat shows. 'Attendance at cat shows' was the only variable significant in both the univariable and multivariable analyses (P <0.05). No significant association was found between the presence of T foetus and diarrhea at the time of sampling or having a history of diarrhea in the past 6 months. The prevalence of T foetus was highly variable among populations of cats in southern Ontario, with shedding being most common in show cats.

  1. Filtered Density Function for Subgrid Scale Modeling of Turbulent Combustion

    DTIC Science & Technology

    2009-02-25

    Turbulent Jet Flow, in Knight, D . and Sakell, L ., editors, Recent Advances in DNS and LES, Fluid Mechanics and its Applications, Vol. 54, pp. 155-166...Simulations: Application to a Turbulent Piloted Methane/Air Diffusion Flame (Sandia D ), Combust. Flame, 145( l -2):88-104 (2006). [29] Jones, W. P., Navarro...density form of SFDF, was developed by Jaberi et al. [14,15] and Garrick et al. [16]. The marginal velocity FDF (VFDF) was developed by Gicquel et

  2. [Platelet count in the cat].

    PubMed

    Moritz, A; Hoffmann, C

    1997-11-01

    The technique of collecting blood samples is primarily responsible for the appearance of platelet-agglomeration in cats. Blood obtained by the conventional way ("one syringe technology", drips of blood) caused in 52% of the cases an activation of the large and therefore active thrombocytes however. Rejection of the first 2-5 ml blood for the platelet count ("two syringe technology") reduced the rate of platelet-agglomeration significantly. No big differences in platelet-agglomeration were found with regard to the place used for collecting blood (V. cephalica antebrachii/V. jugularis). Platelet-agglutination was observed with Li-Heparin, K-EDTA, Na-Citrat or ACD anticoagulated blood samples. Citrat (Na-Citrat, ACD) seemed to have a stabilizing effect on feline thrombocytes as has been described for human thrombocytes. The platelet count in cats should be performed within 30 minutes.

  3. Myeloproliferative disease in a cat

    SciTech Connect

    Yates, R.W.; Weller, R.E.; Feldman, B.F.

    1984-10-01

    Myeloproliferative disorders, a complex of cytologic abnormalities arising in the bone marrow, are among domestic animals most frequently recognized in cats but are relatively uncommon. A 4-year-old female Siamese, with splenomegaly and weight loss, was listless, anorectic, pale and dehydrated. A hemogram showed severe, macrocytic normochromic anemia, leukocytosis and reticulocytosis, with abnormally high numbers of nucleated RBC and undifferentiated blast cells. Bone marrow smears contained predominantly undifferentiated blast cells, RBC precursors and myeloblasts. The fluorescent antibody test for FeLV was positive. The cat died 66 days later despite a blood transfusion and chemotherapy. Necropsy confirmed a diagnosis of myeloproliferative disease, with hepatic and splenic invasion. 15 references, 5 figures, 1 table.

  4. Eosinophilic leukaemia in a cat.

    PubMed

    Sharifi, Hassan; Nassiri, Seyed Mahdi; Esmaelli, Hossein; Khoshnegah, Javad

    2007-12-01

    A 14-year-old female domestic shorthair cat was presented to Tehran University Veterinary Teaching Hospital for a persistent fever, anorexia, intermittent vomiting, weight loss and weakness. The main clinical signs were pale mucous membranes, dehydration and splenomegaly. The complete blood count and serum biochemistry tests revealed non-regenerative anaemia, thrombocytopenia and increased alkaline phosphatase (ALP) activity. An enzyme-linked immunosorbent assay (ELISA) test for feline leukaemia virus was negative. Blood film and bone marrow examination revealed a large number of immature eosinophils with variable sizes and numbers of faintly azurophilic granules. Cytochemical staining of blood film demonstrated 70% positive cells for ALP activity. Four percent CD34 positive cells were detected by flow cytometry. As eosinophilic leukaemia is difficult to identify by light microscopy, well-defined diagnostic criteria and the use of flow cytometry and cytochemical staining can improve the ability to correctly diagnose this type of leukaemia in cats.

  5. Scaling of turbulent flame speed for expanding flames with Markstein diffusion considerations

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Swetaprovo; Wu, Fujia; Law, Chung K.

    2013-09-01

    In this paper we clarify the role of Markstein diffusivity, which is the product of the planar laminar flame speed and the Markstein length, on the turbulent flame speed and its scaling, based on experimental measurements on constant-pressure expanding turbulent flames. Turbulent flame propagation data are presented for premixed flames of mixtures of hydrogen, methane, ethylene, n-butane, and dimethyl ether with air, in near-isotropic turbulence in a dual-chamber, fan-stirred vessel. For each individual fuel-air mixture presented in this work and the recently published iso-octane data from Leeds, normalized turbulent flame speed data of individual fuel-air mixtures approximately follow a ReT,f0.5 scaling, for which the average radius is the length scale and thermal diffusivity is the transport property of the turbulence Reynolds number. At a given ReT,f, it is experimentally observed that the normalized turbulent flame speed decreases with increasing Markstein number, which could be explained by considering Markstein diffusivity as the leading dissipation mechanism for the large wave number flame surface fluctuations. Consequently, by replacing thermal diffusivity with the Markstein diffusivity in the turbulence Reynolds number definition above, it is found that normalized turbulent flame speeds could be scaled by ReT,M0.5 irrespective of the fuel, equivalence ratio, pressure, and turbulence intensity for positive Markstein number flames.

  6. Scaling of turbulent flame speed for expanding flames with Markstein diffusion considerations.

    PubMed

    Chaudhuri, Swetaprovo; Wu, Fujia; Law, Chung K

    2013-09-01

    In this paper we clarify the role of Markstein diffusivity, which is the product of the planar laminar flame speed and the Markstein length, on the turbulent flame speed and its scaling, based on experimental measurements on constant-pressure expanding turbulent flames. Turbulent flame propagation data are presented for premixed flames of mixtures of hydrogen, methane, ethylene, n-butane, and dimethyl ether with air, in near-isotropic turbulence in a dual-chamber, fan-stirred vessel. For each individual fuel-air mixture presented in this work and the recently published iso-octane data from Leeds, normalized turbulent flame speed data of individual fuel-air mixtures approximately follow a Re_{T,f}^{0.5} scaling, for which the average radius is the length scale and thermal diffusivity is the transport property of the turbulence Reynolds number. At a given Re_{T,f}^{}, it is experimentally observed that the normalized turbulent flame speed decreases with increasing Markstein number, which could be explained by considering Markstein diffusivity as the leading dissipation mechanism for the large wave number flame surface fluctuations. Consequently, by replacing thermal diffusivity with the Markstein diffusivity in the turbulence Reynolds number definition above, it is found that normalized turbulent flame speeds could be scaled by Re_{T,M}^{0.5} irrespective of the fuel, equivalence ratio, pressure, and turbulence intensity for positive Markstein number flames.

  7. Differences between vocalization evoked by social stimuli in feral cats and house cats.

    PubMed

    Yeon, Seong C; Kim, Young K; Park, Se J; Lee, Scott S; Lee, Seung Y; Suh, Euy H; Houpt, Katherine A; Chang, Hong H; Lee, Hee C; Yang, Byung G; Lee, Hyo J

    2011-06-01

    To investigate how socialization can affect the types and characteristics of vocalization produced by cats, feral cats (n=25) and house cats (n=13) were used as subjects, allowing a comparison between cats socialized to people and non-socialized cats. To record vocalization and assess the cats' responses to behavioural stimuli, five test situations were used: approach by a familiar caretaker, by a threatening stranger, by a large doll, by a stranger with a dog and by a stranger with a cat. Feral cats showed extremely aggressive and defensive behaviour in most test situations, and produced higher call rates than those of house cats in the test situations, which could be attributed to less socialization to other animals and to more sensitivity to fearful situations. Differences were observed in the acoustic parameters of feral cats in comparison to those of house cats. The feral cat produced significantly higher frequency in fundamental frequency, peak frequency, 1st quartile frequency, 3rd quartile frequency of growls and hisses in agonistic test situations. In contrast to the growls and hisses, in meow, all acoustic parameters like fundamental frequency, first formant, peak frequency, 1st quartile frequency, and 3rd quartile frequency of house cats were of significantly higher frequency than those of feral cats. Also, house cats produced calls of significantly shorter in duration than feral cats in agonistic test situations. These results support the conclusion that a lack of socialization may affect usage of types of vocalizations, and the vocal characteristics, so that the proper socialization of cat may be essential to be a suitable companion house cat.

  8. Direct transmission of the cat flea (Ctenocephalides felis) between cats exhibiting social behaviour

    PubMed Central

    Franc, Michel; Bouhsira, Émilie; Beugnet, Frédéric

    2013-01-01

    A study design was created to assess the potential for fleas to infest cats directly from other cats. In the first experiment, six cats were infested with 100 fleas each and then immediately put in contact with six flea-free cats for 24 h. After removal of all fleas the study was repeated and the contact between cats lasted 48 h. The total numbers of fleas recovered out of the 600 fleas deposited on the 6 donor cats after each infestation were 499 and 486 at 24 h and 48 h respectively. At 1 h post-contact, five fleas were found on the receiver cats, with three cats having one flea and one cat, two fleas. The number of fleas recovered on receiver cats increased towards the end of the study. At 24 h, 20% of the fleas were found on the receiver cats, and at 48 h, 23%. In a second experiment, the six flea-free cats were put in contact with the six donor cats which were each infested by 100 fleas 48 h before. Fewer fleas were found on the receiver cats (n = 15), representing 3.8% of all fleas recovered (n = 403). All the observed fleas had fed. The fleas collected on receiving cats comprised 10 males and 5 females, and 4 of the 5 females were engorged and contained eggs. The fleas collected on donor cats comprised 153 males and 235 females, they were all fed and all females contained eggs. This experiment demonstrated that gravid female fleas have a tendency to become permanently but not exclusively parasitic. Nevertheless, a few can change their cat host in as little as 1 h, which may play a role in the rapid introduction of a new flea population into a cat environment. PMID:24309021

  9. Pharmacokinetics of amantadine in cats.

    PubMed

    Siao, K T; Pypendop, B H; Stanley, S D; Ilkiw, J E

    2011-12-01

    This study reports the pharmacokinetics of amantadine in cats, after both i.v. and oral administration. Six healthy adult domestic shorthair female cats were used. Amantadine HCl (5 mg/kg, equivalent to 4 mg/kg amantadine base) was administered either intravenously or orally in a crossover randomized design. Blood samples were collected immediately prior to amantadine administration, and at various times up to 1440 min following intravenous, or up to 2880 min following oral administration. Plasma amantadine concentrations were determined by liquid chromatography-mass spectrometry, and plasma amantadine concentration-time data were fitted to compartmental models. A two-compartment model with elimination from the central compartment best described the disposition of amantadine administered intravenously in cats, and a one-compartment model best described the disposition of oral amantadine in cats. After i.v. administration, the apparent volume of distribution of the central compartment and apparent volume of distribution at steady-state [mean ± SEM (range)], and the clearance and terminal half-life [harmonic mean ± jackknife pseudo-SD (range)] were 1.5 ± 0.3 (0.7-2.5) L/kg, 4.3 ± 0.2 (3.7-5.0) L/kg, 8.2 ± 2.1 (5.9-11.4) mL·min/kg, and 348 ± 49 (307-465) min, respectively. Systemic availability [mean ± SEM (range)] and terminal half-life after oral administration [harmonic mean ± jackknife pseudo-SD (range)] were 130 ± 11 (86-160)% and 324 ± 41 (277-381) min, respectively.

  10. Ototoxicity in dogs and cats.

    PubMed

    Oishi, Naoki; Talaska, Andra E; Schacht, Jochen

    2012-11-01

    A variety of drugs in veterinary use have side effects that can potentially damage the senses of hearing or balance in animals. A large body of literature exists on the incidence and mechanisms of ototoxicity in experimental animals and in humans, but little is documented in domestic dogs and cats. However, the generality of these adverse actions across species allows one to extrapolate and provide the veterinarian with insight into possible complications of chemotherapy.

  11. Turbulent Flow Validation in the Helios Strand Solver

    DTIC Science & Technology

    2014-01-07

    further details on the complexities of rotorcraft modeling . The Helios software was introduced as a rotary- wing product of the of the CREATE-AV (air...options can be invoked in NSU3D. (a) α = 45o (b) α = 60o Figure 2. Stalled NACA 0012 wing atM∞ = 0.15, computed density contours with DES turbulence model ...Allmaras, given in reference .? II.B.1. Spalart Allmaras Turbulence model In this work two forms of the SA turbulence model are employed: one corresponding to

  12. Cat Scratch Disease: Expanded Spectrum

    PubMed Central

    Aziz, Hassan A.; Plesec, Thomas P.; Sabella, Camille; Udayasankar, Unni K.; Singh, Arun D.

    2016-01-01

    Background To expand the spectrum of ophthalmic manifestations in cat scratch disease. Methods Case report. Results A 7-year-old male was referred for evaluation of his left optic disc after failing vision screening test at school. His visual acuity was 20/20 OD and light perception OS. Fundus examination showed a left optic disc lesion associated with an exudative retinal detachment and vitreous seeding. Ultrasonography revealed a 7 × 7.5 × 3.8 mm lesion with a possible 6.3 mm of retrolaminar extension into the substance of the optic nerve. Brain MRI did not show evidence of optic nerve involvement but revealed a 6-mm nodule of the pineal gland suggestive of a pineoblastoma. Enucleation was performed and histopathology revealed a suppurative granulomatous inflammation suggestive of Bartonella infection. Upon further questioning, the patient had recent exposure to kittens with areas of cat scratches along both of his arms. He was subsequently referred to and treated with a 2-week course of trimethoprim-sulfamethoxazole and rifampin by the pediatric infectious disease specialist. Repeat brain MRI showed interval total resolution of enlarged pineal gland. Conclusion: Optic nerve granulomas are a rare presentation of cat scratch disease and could potentially masquerade as retinoblastoma. PMID:27843905

  13. Hypophosphatemia associated with enteral alimentation in cats.

    PubMed

    Justin, R B; Hohenhaus, A E

    1995-01-01

    Hypophosphatemia is uncommon in cats, but it has been reported in association with diabetes mellitus and hepatic lipidosis, where it can cause hemolysis, rhabdomyopathy, depression, seizures, and coma. The purpose of this article is to describe 9 cats that developed low serum phosphorus concentrations (< 2.5 mg/dL) subsequent to enteral alimentation. Serum biochemical analyses from more than 6,000 cats were reviewed. The medical records of all cats with hypophosphatemia were examined for history of enteral alimentation; diabetic cats were excluded from the study. Nine cats, ranging in age from 3 to 17 years, were identified. All cats had normal serum phosphorus concentrations before tube feeding began. Onset of hypophosphatemia occurred 12 to 72 hours after initiation of enteral alimentation, and the nadir for phosphorus concentrations ranged from 0.4 to 2.4 mg/dL. Hemolysis occurred in 6 of the 9 cats. Hypophosphatemia secondary to enteral alimentation is an uncommon clinical finding in cats. Cats with high alanine aminotransferase activity, hyperbilirubinemia, and weight loss should be closely monitored for hypophosphatemia during the first 72 hours of enteral alimentation.

  14. Radioactive iodine therapy in cats with hyperthyroidism

    SciTech Connect

    Turrel, J.M.; Feldman, E.C.; Hays, M.; Hornof, W.J.

    1984-03-01

    Eleven cats with hyperthyroidism were treated with radioactive iodine (/sup 131/I). Previous unsuccessful treatments for hyperthyroidism included hemithyroidectomy (2 cats) and an antithyroid drug (7 cats). Two cats had no prior treatment. Thyroid scans, using technetium 99m, showed enlargement and increased radionuclide accumulation in 1 thyroid lobe in 5 cats and in both lobes in 6 cats. Serum thyroxine concentrations were high and ranged from 4.7 to 18 micrograms/dl. Radioactive iodine tracer studies were used to determine peak radioactive iodine uptake (RAIU) and effective and biological half-lives. Activity of /sup 131/I administered was calculated from peak RAIU, effective half-life, and estimated thyroid gland weight. Activity of /sup 131/I administered ranged from 1.0 to 5.9 mCi. The treatment goal was to deliver 20,000 rad to hyperactive thyroid tissue. However, retrospective calculations based on peak RAIU and effective half-life obtained during the treatment period showed that radiation doses actually ranged from 7,100 to 64,900 rad. Complete ablation of the hyperfunctioning thyroid tissue and a return to euthyroidism were seen in 7 cats. Partial responses were seen in 2 cats, and 2 cats became hypothyroid. It was concluded that /sup 131/I ablation of thyroid tumors was a reasonable alternative in the treatment of hyperthyroidism in cats. The optimal method of dosimetry remains to be determined.

  15. Dispersion of Droplet Clouds in Turbulence.

    PubMed

    Bocanegra Evans, Humberto; Dam, Nico; Bertens, Guus; van der Voort, Dennis; van de Water, Willem

    2016-10-14

    We measure the absolute dispersion of clouds of monodisperse, phosphorescent droplets in turbulent air by means of high-speed image-intensified video recordings. Laser excitation allows the initial preparation of well-defined, pencil-shaped luminous droplet clouds in a completely nonintrusive way. We find that the dispersion of the clouds is faster than the dispersion of fluid elements. We speculate that preferential concentration of inertial droplet clouds is responsible for the enhanced dispersion.

  16. PREFACE: Turbulent Mixing and Beyond Turbulent Mixing and Beyond

    NASA Astrophysics Data System (ADS)

    Abarzhi, Snezhana I.; Gauthier, Serge; Rosner, Robert

    2008-10-01

    (continuous DNS/LES/RANS, Molecular dynamics, Monte-Carlo, predictive modeling) New Experimental Diagnostics (novel methods for flow visualization and control, high-tech) The First International Conference `Turbulent Mixing and Beyond' was organized by the following members of the Organizing Committee: Snezhana I Abarzhi (chairperson, Chicago, USA) Malcolm J Andrews (Los Alamos National Laboratory, USA) Sergei I Anisimov (Landau Institute for Theoretical Physics, Russia) Serge Gauthier (Commissariat à l'Energie Atomique, France) Donald Q Lamb (The University of Chicago, USA) Katsunobu Nishihara (Institute for Laser Engineering, Osaka, Japan) Bruce A Remington (Lawrence Livermore National Laboratory, USA) Robert Rosner (Argonne National Laboratory, USA) Katepalli R Sreenivasan (International Centre for Theoretical Physics, Italy) Alexander L Velikovich (Naval Research Laboratory, USA) The Organizing Committee gratefully acknowledges the financial support of the Conference Sponsors: National Science Foundation (NSF), USA (Divisions and Programs Directors: Drs A G Detwiler, L M Jameson, E L Lomon, P E Phelan, G A Prentice, J A Raper, W Schultz, P R Westmoreland; PI: Dr S I Abarzhi) Air Force Office of Scientific Research (AFOSR), USA (Program Director: Dr J D Schmisseur; PI: Dr S I Abarzhi) European Office of Aerospace Research and Development (EOARD) of the AFOSR, UK (Program Chief: Dr S Surampudi; PI: Dr S I Abarzhi) International Centre for Theoretical Physics (ICTP), Trieste, Italy (Centre's Director: Dr K R Sreenivasan) The University of Chicago and The Argonne National Laboratory (ANL), USA (Laboratory's Director: Dr R Rosner) Commissariat à l'Energie Atomique (CEA), France (Directeur de Recherche: Dr S Gauthier) Department of Energy, Los Alamos National Laboratory (LANL), USA (Program manager: Dr R J Hanrahan; Group Leader: Dr M J Andrew) The DOE ASC Alliance Center for Astrophysical Thermonuclear Flashes, The University of Chicago, USA (Center's Director: Dr D Q Lamb

  17. Edge turbulence in tokamaks

    NASA Astrophysics Data System (ADS)

    Nedospasov, A. V.

    1992-12-01

    Edge turbulence is of decisive importance for the distribution of particle and energy fluxes to the walls of tokamaks. Despite the availability of extensive experimental data on the turbulence properties, its nature still remains a subject for discussion. This paper contains a review of the most recent theoretical and experimental studies in the field, including mainly the studies to which Wootton (A.J. Wooton, J. Nucl. Mater. 176 & 177 (1990) 77) referred to most in his review at PSI-9 and those published later. The available theoretical models of edge turbulence with volume dissipation due to collisions fail to fully interpret the entire combination of experimental facts. In the scrape-off layer of a tokamak the dissipation prevails due to the flow of current through potential shifts near the surface of limiters of divertor plates. The different origins of turbulence at the edge and in the core plasma due to such dissipation are discussed in this paper. Recent data on the electron temperature fluctuations enabled one to evaluate the electric probe measurements of turbulent flows of particles and heat critically. The latest data on the suppression of turbulence in the case of L-H transitions are given. In doing so, the possibility of exciting current instabilities in biasing experiments (rather than only to the suppression of existing turbulence) is given some attention. Possible objectives of further studies are also discussed.

  18. Turbulent scaling in fluids

    SciTech Connect

    Ecke, R.; Li, Ning; Chen, Shiyi; Liu, Yuanming

    1996-11-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project was a study of turbulence in fluids that are subject to different body forces and to external temperature gradients. Our focus was on the recent theoretical prediction that the Kolomogorov picture of turbulence may need to be modified for turbulent flows driven by buoyancy and subject to body forces such as rotational accelerations. Models arising from this research are important in global climate modeling, in turbulent transport problems, and in the fundamental understanding of fluid turbulence. Experimentally, we use (1) precision measurements of heat transport and local temperature; (2) flow visualization using digitally- enhanced optical shadowgraphs, particle-image velocimetry, thermochromic liquid-crystal imaging, laser-doppler velocimetry, and photochromic dye imaging; and (3) advanced image- processing techniques. Our numerical simulations employ standard spectral and novel lattice Boltzmann algorithms implemented on parallel Connection Machine computers to simulate turbulent fluid flow. In laboratory experiments on incompressible fluids, we measure probability distribution functions and two-point spatial correlations of temperature T and velocity V (both T-T and V-T correlations) and determine scaling relations for global heat transport with Rayleigh number. We also explore the mechanism for turbulence in thermal convection and the stability of the thermal boundary layer.

  19. Modeling turbulent flame propagation

    SciTech Connect

    Ashurst, W.T.

    1994-08-01

    Laser diagnostics and flow simulation techniques axe now providing information that if available fifty years ago, would have allowed Damkoehler to show how turbulence generates flame area. In the absence of this information, many turbulent flame speed models have been created, most based on Kolmogorov concepts which ignore the turbulence vortical structure, Over the last twenty years, the vorticity structure in mixing layers and jets has been shown to determine the entrainment and mixing behavior and these effects need to be duplicated by combustion models. Turbulence simulations reveal the intense vorticity structure as filaments and simulations of passive flamelet propagation show how this vorticity Creates flame area and defines the shape of the expected chemical reaction surface. Understanding how volume expansion interacts with flow structure should improve experimental methods for determining turbulent flame speed. Since the last decade has given us such powerful new tools to create and see turbulent combustion microscopic behavior, it seems that a solution of turbulent combustion within the next decade would not be surprising in the hindsight of 2004.

  20. Classical Vs. Superfluid Turbulence

    NASA Astrophysics Data System (ADS)

    Roche, P.-E.

    2008-11-01

    Thanks to a zero-viscosity, superfluids offer a unique testing ground for hydrodynamic models, in particular for turbulence ones. In Kolmogorov's turbulence model, viscosity is well known to damp the kinetic energy of the smallest eddies, and thus to introduce a cut-off at one end of the turbulent cascade. Significant differences between this ``classical'' turbulence and the turbulence of a superfluid are therefore expected, but --surprisingly- most experiments rather evidenced strong similarities. We will give an overview of a set of experiments designed to compare in details the classical versus superfluid turbulences, up to a record mass flow of superfluid (700g/s of He @ 1.6K). Then, we will focus on some unexpected vorticity measurements, which can be interpreted assuming that the superfluid vortices are passively advected by the largest scales of the flow, in contrast with the ``classical'' turbulence counterpart. Numerical simulations -based on regular DNS- will be presented to complete this interpretation. In collaboration with C. Barenghi, University of Newcastle; B. Castaing and E. Levèque, ENSL, Lyon; S. David, IEF, CNRS, Orsay; B. Rousset, SBT/CEA, Grenoble; and P. Tabeling, H. Willaime MMN, ESPCI, Paris.

  1. Wall turbulence control

    NASA Technical Reports Server (NTRS)

    Wilkinson, Stephen P.; Lindemann, A. Margrethe; Beeler, George B.; Mcginley, Catherine B.; Goodman, Wesley L.; Balasubramanian, R.

    1986-01-01

    A variety of wall turbulence control devices which were experimentally investigated are discussed; these include devices for burst control, alteration of outer flow structures, large eddy substitution, increased heat transfer efficiency, and reduction of wall pressure fluctuations. Control of pre-burst flow was demonstrated with a single, traveling surface depression which is phase-locked to elements of the burst production process. Another approach to wall turbulence control is to interfere with the outer layer coherent structures. A device in the outer part of a boundary layer was shown to suppress turbulence and reduce drag by opposing both the mean and unsteady vorticity in the boundary layer. Large eddy substitution is a method in which streamline curvature is introduced into the boundary layer in the form of streamwise vortices. Riblets, which were already shown to reduce turbulent drag, were also shown to exhibit superior heat transfer characteristics. Heat transfer efficiency as measured by the Reynolds Analogy Factor was shown to be as much as 36 percent greater than a smooth flat plate in a turbulent boundary layer. Large Eddy Break-Up (LEBU) which are also known to reduce turbulent drag were shown to reduce turbulent wall pressure fluctuation.

  2. Effect of free-stream turbulence on film cooling

    NASA Technical Reports Server (NTRS)

    Marek, C. J.; Tacina, R. R.

    1975-01-01

    Film-cooling experiments were conducted at four levels of free-stream turbulence to test the hypothesis that the film-cooling effectiveness is inversely related to the free-stream turbulence level. The hot-gas operating conditions were held constant at a temperature of 590 K, a pressure of 1 atmosphere, and a velocity of 62 m/sec. The film-cooling air was at ambient inlet temperature, and the film-cooling flow rates were 2.5, 5.0, 7.5, and 10.0 percent of the total airflow. Blockage plates with blockage areas of 0, 52, 72, and 90 percent were placed upstream of the film-cooling slot and produced axial turbulence intensities of 7, 14, 23, and 35 percent, respectively. The film-cooling effectiveness decreased as much as 50 percent as the freestream turbulence intensity was increased from 7 to 35 percent. The value of the turbulent mixing coefficient used in previous work was compared with the axial turbulence intensity. The turbulent mixing coefficient was found to be 10 to 40 percent of the axial turbulence intensity.

  3. Triglyceride response following an oral fat tolerance test in Burmese cats, other pedigree cats and domestic crossbred cats.

    PubMed

    Kluger, Elissa K; Hardman, Chloë; Govendir, Merran; Baral, Randolph M; Sullivan, David R; Snow, David; Malik, Richard

    2009-02-01

    Primary lipid disorders causing fasting triglyceridaemia have been documented infrequently in Burmese cats. Due to the known increased risk of diabetes mellitus and sporadic reports of lipid aqueous in this breed, the aim of this study was to determine whether healthy Burmese cats displayed a more pronounced pre- or post-prandial triglyceridaemia compared to other cats. Serum triglyceride (TG) concentrations were determined at baseline and variably at 2, 4 and 6h after ingestion of a high-fat meal (ie, an oral fat tolerance test) in a representative sample of Burmese and non-Burmese cats. The median 4 and 6h serum TG concentrations were significantly higher in Burmese cats (4h - 2.8mmol/l; 6h - 8.2mmol/l) than in other pedigree and domestic crossbred cats (4h - 1.5mmol/l; 6h - 1.0mmol/l). The non-Burmese group had post-prandial TG concentrations ranging from 0.6 to 3.9mmol/l. Seven Burmese cats had post-prandial TG concentrations between 6.6 and 19.0mmol/l, five had concentrations between 4.2 and 4.7mmol/l, while the remaining 15 had post-prandial concentrations between 0.5 and 2.8mmol/l. None of these Burmese cats had fasting triglyceridaemia. Most Burmese cats with a 4 h TG > 6.0 mmol/l had elevated fasting very low density lipoprotein (VLDL) concentrations. This study demonstrates that a proportion of Burmese cats in Australia have delayed TG clearance compared to other cats. The potential repercussions of this observation with reference to lipid aqueous, pancreatitis and diabetes mellitus in Burmese cats are discussed.

  4. Modeling of turbulent chemical reaction

    NASA Technical Reports Server (NTRS)

    Chen, J.-Y.

    1995-01-01

    Viewgraphs are presented on modeling turbulent reacting flows, regimes of turbulent combustion, regimes of premixed and regimes of non-premixed turbulent combustion, chemical closure models, flamelet model, conditional moment closure (CMC), NO(x) emissions from turbulent H2 jet flames, probability density function (PDF), departures from chemical equilibrium, mixing models for PDF methods, comparison of predicted and measured H2O mass fractions in turbulent nonpremixed jet flames, experimental evidence of preferential diffusion in turbulent jet flames, and computation of turbulent reacting flows.

  5. On the decay of homogeneous isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Skrbek, L.; Stalp, Steven R.

    2000-08-01

    wind tunnels and a water channel, the temporal decay of turbulence created by an oscillating grid in water and the decay of energy and vorticity created by a towed grid in a stationary sample of water. We also analyze decaying vorticity data we obtained in superfluid helium and show that decaying superfluid turbulence can be described classically. This paper offers a unified investigation of decaying isotropic, homogeneous turbulence that is based on accepted forms of the three-dimensional turbulent spectra and a variety of experimental decay data obtained in air, water, and superfluid helium.

  6. Measurement of Turbulence in the Oceanic Mixed Layer Using Synthetic Aperture Radar (SAR)

    NASA Astrophysics Data System (ADS)

    George, Simon G.; Tatnall, Adrian R. L.

    2012-03-01

    Improved understanding of the cause and character of turbulence is increasingly important for applications such as climate change: Turbulent processes near the surface layer of the ocean contribute greatly to momentum, heat and flux transfers across the air-sea boundary. Such processes are most commonly observed in Synthetic Aperture Radar (SAR) imagery as the turbulent wake present behind a moving surface vessel or ship, but also in the radar backscatter signatures of breaking surface & internal waves, convection, eddies, etc. Fine-resolution turbulent wake flows were computed numerically using Direct Numerical Simulation and the interaction of small-scale wake turbulence with the free surface studied using a hydrodynamic interaction model. The resulting modulated surface currents were subsequently processed through radar simulation algorithms to generate simulated radar images of the wake and demonstrating the ability of SAR to observe and characterise surface turbulent flows which contribute to exchange processes at the air-sea interface.

  7. One-dimensional turbulence model simulations of autoignition of hydrogen/carbon monoxide fuel mixtures in a turbulent jet

    SciTech Connect

    Gupta, Kamlesh G.; Echekki, Tarek

    2011-02-15

    The autoignition of hydrogen/carbon monoxide in a turbulent jet with preheated co-flow air is studied using the one-dimensional turbulence (ODT) model. The simulations are performed at atmospheric pressure based on varying the jet Reynolds number and the oxidizer preheat temperature for two compositions corresponding to varying the ratios of H{sub 2} and CO in the fuel stream. Moreover, simulations for homogeneous autoignition are implemented for similar mixture conditions for comparison with the turbulent jet results. The results identify the key effects of differential diffusion and turbulence on the onset and eventual progress of autoignition in the turbulent jets. The differential diffusion of hydrogen fuels results in a reduction of the ignition delay relative to similar conditions of homogeneous autoignition. Turbulence may play an important role in delaying ignition at high-turbulence conditions, a process countered by the differential diffusion of hydrogen relative to carbon monoxide; however, when ignition is established, turbulence enhances the overall rates of combustion of the non-premixed flame downstream of the ignition point. (author)

  8. A review of feral cat control.

    PubMed

    Robertson, Sheilah A

    2008-08-01

    Animal overpopulation including feral cats is an important global problem. There are many stakeholders involved in the feral cat debate over 'what to do about the problem', including those who consider them a nuisance, the public at risk from zoonotic disease, people who are concerned about the welfare of feral cats, those concerned with wildlife impacts, and the cats themselves. How best to control this population is controversial and has ranged from culling, relocation, and more recently 'trap neuter return' (TNR) methods. Data support the success of TNR in reducing cat populations, but to have a large impact it will have to be adopted on a far greater scale than it is currently practised. Non-surgical contraception is a realistic future goal. Because the feral cat problem was created by humans, concerted educational efforts on responsible pet ownership and the intrinsic value of animals is an integral part of a solution.

  9. Molecular Detection of Rickettsia felis in Humans, Cats, and Cat Fleas in Bangladesh, 2013-2014.

    PubMed

    Ahmed, Rajib; Paul, Shyamal Kumar; Hossain, Muhammad Akram; Ahmed, Salma; Mahmud, Muhammad Chand; Nasreen, Syeda Anjuman; Ferdouse, Faria; Sharmi, Rumana Hasan; Ahamed, Farid; Ghosh, Souvik; Urushibara, Noriko; Aung, Meiji Soe; Kobayashi, Nobumichi

    2016-05-01

    High prevalence of Rickettsia felis in patients with fever of unknown origin was revealed in the north-central Bangladesh from 2012 to 2013. Subsequently, in this study, prevalence of R. felis in cats and cat fleas (Ctenocephalides felis), together with febrile patients, was studied by PCR detection of 17 kDa antigen gene and DNA sequencing. R. felis was detected in 28% (28/100) and 21% (14/68) of cat blood and cat flea samples, respectively, whereas 42% (21/50) of patients were positive for R. felis. R. felis-positive cat fleas were detected at significantly higher rate on R. felis-positive cats. The results suggested a potential role of cats and cat fleas for transmission of R. felis to humans in Bangladesh.

  10. DESCRIPTION OF ATMOSPHERIC TRANSPORT PROCESSES IN EULERIAN AIR QUALITY MODELS

    EPA Science Inventory

    Key differences among many types of air quality models are the way atmospheric advection and turbulent diffusion processes are treated. Gaussian models use analytical solutions of the advection-diffusion equations. Lagrangian models use a hypothetical air parcel concept effecti...

  11. Diagnostic Exercise: Neurologic Disorder in a Cat

    DTIC Science & Technology

    1989-12-21

    dogs and a cat . Vet Pathol 1987;24:192-194. 4. Migaki G, Casey HW, Bayles WB. Cerebral phaeohyphomycosis in a dog . J Am Vet Med Assoc 1987;191(8):997...IWORK UNIT ELEMENT NO. NO. NO. ACCESSION NO. 11. TITLE (Include Security Classification) Diagnostic Exercise - Neurologic Disorder in a Cat 12...and identify by block number) This report documents the fifth reported occurrance of cerebral phaeophyphomycosis in cats . Because mycotic

  12. Incidence of pyometra in Swedish insured cats.

    PubMed

    Hagman, Ragnvi; Ström Holst, Bodil; Möller, Lotta; Egenvall, Agneta

    2014-07-01

    Pyometra is a clinically relevant problem in intact female cats and dogs. The etiology is similar in both animal species, with the disease caused by bacterial infection of a progesterone-sensitized uterus. Here, we studied pyometra in cats with the aim to describe the incidence and probability of developing pyometra based on age and breed. The data used were reimbursed claims for veterinary care insurance or life insurance claims or both in cats insured in a Swedish insurance database from 1999 to 2006. The mean incidence rate (IR) for pyometra was about 17 cats per 10,000 cat years at risk (CYAR). Cats with pyometra were diagnosed at a median age of 4 years and a significant breed effect was observed. The breed with the highest IR (433 cats per 10,000 CYAR) was the Sphynx, and other breeds with IR over 60 cats per 10,000 CYAR were Siberian cat, Ocicat, Korat, Siamese, Ragdoll, Maine coon, and Bengal. Pyometra was more commonly diagnosed with increasing age, with a marked increase in cats older than 7 years. The mean case fatality rate in all cats was 5.7%, which is slightly higher than corresponding reports in dogs of 3% to 4%. Geographical location (urban or rural) did not affect the risk of developing the disease. The present study provides information of incidence and probability of developing pyometra based on age, breed, and urban or rural geographical location. These data may be useful for designing cat breeding programs in high-risk breeds and for future studies of the genetic background of the disease.

  13. Pulmonary transcription of CAT-2 and CAT-2B but not CAT-1 and CAT-2A were upregulated in hemorrhagic shock rats.

    PubMed

    Huang, Chun-Jen; Tsai, Pei-Shan; Yang, Chen-Hsien; Su, Tsung-Hsien; Stevens, Bruce R; Skimming, Jeffrey W; Pan, Wynn H T

    2004-11-01

    Hemorrhagic shock stimulates nitric oxide (NO) biosynthesis through upregulation of inducible NO synthase (iNOS) expression. Trans-membrane l-arginine transportation mediated by the isozymes of cationic amino acid transporters (e.g. CAT-1, CAT-2, CAT-2A, and CAT-2B) is one crucial regulatory mechanism that regulates iNOS activity. We sought to assess the effects of hemorrhage and resuscitation on the expression of these regulatory enzymes in hemorrhage-stimulated rat lungs. Twenty-four rats were randomized to a sham-instrumented group, a sustained shock group, a shock with blood resuscitation group, or a shock with normal saline resuscitation group. Hemorrhagic shock was induced by withdrawing blood to maintain MAP between 40 and 45mmHg for 60min. Resuscitation by infusing blood/saline mixtures (blood resuscitation group) or saline alone (saline resuscitation group) was then performed. At the end of the experiment (300min after hemorrhage began), rats were sacrificed and enzymes expression as well as pulmonary NO biosynthesis and lung injuries were assayed. Our data revealed that hemorrhage-induced pulmonary iNOS, CAT-2, and CAT-2B transcription which was associated with pulmonary NO overproduction and subsequent lung injury. Resuscitation significantly attenuated the hemorrhage-induced enzyme upregulation, pulmonary NO overproduction, and lung injury. Blood/saline mixtures were superior to saline as a resuscitation solution in treating hemorrhage-induced pulmonary NO overproduction and lung injury. Hemorrhage and/or resuscitation, however, did not affect the expression of pulmonary CAT-1 and CAT-2A. It is, therefore, concluded that the expression of pulmonary iNOS, CAT-2, and CAT-2B is inducible and that of CAT-1 and CAT-2A is constitutive in hemorrhagic shock rat lungs.

  14. Cats and Toxoplasma: implications for public health.

    PubMed

    Dabritz, H A; Conrad, P A

    2010-02-01

    Cats are popular as pets worldwide because they are easy to care for and provide companionship that enriches the lives of human beings. Little attention has been focused on their potential to contaminate the environment with zoonotic pathogens. One such pathogen, the protozoan parasite Toxoplasma gondii, rarely causes clinical manifestations in cats or immunocompetent humans; however, it can have serious adverse effects on human foetuses and immunocompromised patients. Many human infections are believed to be acquired from eating undercooked or raw meat, such as pork and lamb (Tenter et al. Int. J. Parasitol., 30, 2000, 1217; Dubey et al. J. Parasitol. 91, 2005, 1082). However, the prevalence of T. gondii infection in human populations that do not consume meat or eat it well-cooked suggests that the acquisition of infection from the environment, via oocysts in soil, water or on uncooked vegetables, is also important (Rawal. Trans. Royal Soc. Trop. Med. Hyg., 53, 1959, 61; Roghmann et al. Am. J. Trop. Med. Hyg., 60, 1999, 790; Chacin-Bonilla et al. Am. J. Trop. Med. Hyg., 65, 2001, 131). In the past 20 years, two changes occurred that significantly increased the size of the cat population in the USA. Pet cat ownership grew from 50 million to 90 million animals, and animal welfare activists created feeding stations for abandoned and free-roaming cats. As many cat owners allow their cats to deposit faeces outside and cats maintained in colonies always defecate outside, ample opportunity exists for T. gondii oocysts to enter the environment and be transmitted to humans. Prevention efforts should focus on educating cat owners about the importance of collecting cat faeces in litter boxes, spaying owned cats to reduce overpopulation, reducing the numbers of feral cats and promoting rigorous hand hygiene after gardening or soil contact.

  15. Turbulent flow through screens

    NASA Technical Reports Server (NTRS)

    Mehta, R. D.

    1984-01-01

    A detailed experimental investigation has been carried out on the effects of different types of screens on turbulent flow, in particular turbulent boundary layers. The effect of a screen on a turbulent boundary layer is to give it a 'new lease of life'. The boundary layer turbulence is reorganized and the thickness reduced, thus making it less susceptible to separation. The aerodynamic properties of plastic screens are found to differ significantly from those of the conventional metal screens, evidently because of differences in the weaving properties. The 'overshoot' in mean velocity profile near the boudnary layer edge is shown to be a result of the effect of screen inclination on pressure drop coefficient. A more accurate formulation for the deflection coefficient of a screen is also proposed.

  16. Inflow Turbulence Generation Methods

    NASA Astrophysics Data System (ADS)

    Wu, Xiaohua

    2017-01-01

    Research activities on inflow turbulence generation methods have been vigorous over the past quarter century, accompanying advances in eddy-resolving computations of spatially developing turbulent flows with direct numerical simulation, large-eddy simulation (LES), and hybrid Reynolds-averaged Navier-Stokes–LES. The weak recycling method, rooted in scaling arguments on the canonical incompressible boundary layer, has been applied to supersonic boundary layer, rough surface boundary layer, and microscale urban canopy LES coupled with mesoscale numerical weather forecasting. Synthetic methods, originating from analytical approximation to homogeneous isotropic turbulence, have branched out into several robust methods, including the synthetic random Fourier method, synthetic digital filtering method, synthetic coherent eddy method, and synthetic volume forcing method. This article reviews major progress in inflow turbulence generation methods with an emphasis on fundamental ideas, key milestones, representative applications, and critical issues. Directions for future research in the field are also highlighted.

  17. Turbulence of swarming sperm

    NASA Astrophysics Data System (ADS)

    Creppy, Adama; Praud, Olivier; Druart, Xavier; Kohnke, Philippa L.; Plouraboué, Franck

    2015-09-01

    Collective motion of self-sustained swarming flows has recently provided examples of small-scale turbulence arising where viscous effects are dominant. We report the first observation of universal enstrophy cascade in concentrated swarming sperm consistent with a body of evidence built from various independent measurements. We found a well-defined k-3 power-law decay of a velocity field power spectrum and relative dispersion of small beads consistent with theoretical predictions in 2D turbulence. Concentrated living sperm displays long-range, correlated whirlpool structures of a size that provides an integral scale of turbulence. We propose a consistent explanation for this quasi-2D turbulence based on self-structured laminated flow forced by steric interactions and alignment, a state of active matter that we call "swarming liquid crystal." We develop scaling arguments consistent with this interpretation.

  18. 42 CFR 71.51 - Dogs and cats.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Dogs and cats. 71.51 Section 71.51 Public Health... QUARANTINE Importations § 71.51 Dogs and cats. (a) Definitions. As used in this section the term: Cat means all domestic cats. Confinement means restriction of a dog or cat to a building or other enclosure at...

  19. 42 CFR 71.51 - Dogs and cats.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Dogs and cats. 71.51 Section 71.51 Public Health... QUARANTINE Importations § 71.51 Dogs and cats. (a) Definitions. As used in this section the term: Cat means all domestic cats. Confinement means restriction of a dog or cat to a building or other enclosure at...

  20. 42 CFR 71.51 - Dogs and cats.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Dogs and cats. 71.51 Section 71.51 Public Health... QUARANTINE Importations § 71.51 Dogs and cats. (a) Definitions. As used in this section the term: Cat means all domestic cats. Confinement means restriction of a dog or cat to a building or other enclosure at...

  1. 42 CFR 71.51 - Dogs and cats.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Dogs and cats. 71.51 Section 71.51 Public Health... QUARANTINE Importations § 71.51 Dogs and cats. (a) Definitions. As used in this section the term: Cat means all domestic cats. Confinement means restriction of a dog or cat to a building or other enclosure at...

  2. 42 CFR 71.51 - Dogs and cats.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Dogs and cats. 71.51 Section 71.51 Public Health... QUARANTINE Importations § 71.51 Dogs and cats. (a) Definitions. As used in this section the term: Cat means all domestic cats. Confinement means restriction of a dog or cat to a building or other enclosure at...

  3. Plume rise, entrainment and dispersion in turbulent winds

    NASA Astrophysics Data System (ADS)

    Netterville, Dennett D. J.

    This paper describes a new analytical model which combines within one theoretical framework several aspects of the phenomena of plume rise, dispersion, thermal stratification and ambient turbulence. The model is based in part on knowledge gained from recent investigations of flow within free shear layers. The observations suggest a simple model for the turbulent mixing process, which accounts for the known entrainment of air into smoke plumes by plume-generated turbulence. More importantly, the model also predicts a path by which ambient turbulence causes reverse entrainment of plume material into the surrounding fluids. This gives rise to a new 'extrainment' term in each of the plume momentum and buoyancy equations. These equations are solved for a turbulent atmosphere of arbitrary thermal stability, and yield plume trajectories which gradually level off at final rise heights that depend on the degree of thermal stratification and on the scale and intensity of ambient turbulence. A link between plume rise and dispersion is identified by means of the concentration species equation, which is solved to show that the plume acts along its length as a distributed source of passively dispersing material. The new theory, specialized for an adiabatic atmosphere, plus the familiar x2/3 law and a semi-empirical final rise theory from the literature, are all compared against full-scale data on plume rise in turbulent winds. The new theory significantly improves the accuracy of estimates of plume trajectory and final plume height. The price for this improved predictive ability is the need to evaluate the air temperature and its gradient at plume level, and the corresponding intensity and scale of turbulent air movement. This is no longer a technical obstacle since recently developed SODAR and RASS remote sensors have this capability.

  4. Whole-Field Measurements of Turbulent Flow for the Study of Aero-optical Effects

    DTIC Science & Technology

    2007-11-02

    Aerooptical phenomena associated with the propagation of optical beams and imaging through turbulent index-of-refraction fields have been investigated...Using simultaneous imaging of optical -beam distortion and the turbulent index-or-refraction field, we have documented near-field behavior, following...of TECHNOLOGY Pasadena, California 91125 Whole-field measurements of turbulent flow for the study of aero- optical effects Paul E. Dimotakis Air

  5. Intermittency exponent of the turbulent energy cascade.

    PubMed

    Cleve, Jochen; Greiner, Martin; Pearson, Bruce R; Sreenivasan, Katepalli R

    2004-06-01

    We consider the turbulent energy dissipation from one-dimensional records in experiments using air and gaseous helium at cryogenic temperatures, and obtain the intermittency exponent via the two-point correlation function of the energy dissipation. The air data are obtained in a number of flows in a wind tunnel and the atmospheric boundary layer at a height of about 35 m above the ground. The helium data correspond to the centerline of a jet exhausting into a container. The air data on the intermittency exponent are consistent with each other and with a trend that increases with the Taylor microscale Reynolds number, R(lambda), of up to about 1000 and saturates thereafter. On the other hand, the helium data cluster around a constant value at nearly all R(lambda), this being about half of the asymptotic value for the air data. Some possible explanation is offered for this anomaly.

  6. [Asthma caused by allergy to cat fur].

    PubMed

    May, K L; Hofman, T

    2000-01-01

    Sensitivity to cats fur alergen, Fel. d. 1 is presented as the second most important cause, after allergy to mites, of perennial atopic asthma. The authors collected the data from literature concerning the concentrations of Fel. d. 1 in homes and public places. Further the structure and production of Fel d. 1 also its cross reactivity and the methods of it's elimination from the environment are described and discussed. Authors own observations of 20 cases of cats fur asthma and atopic dermatitis support the opinion that only half of the patients suspect cats as the cause of their illness and cats fur sensitivity is always accompanied by inhalant or food allergy.

  7. Screening for hypertrophic cardiomyopathy in cats.

    PubMed

    Häggström, Jens; Luis Fuentes, Virginia; Wess, Gerhard

    2015-12-01

    Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats, and it can lead to increased morbidity and mortality. Cats are often screened for HCM because of the presence of a heart murmur, but screening for breeding purposes has also become common. These cats are usually purebred cats of breeding age, and generally do not present with severe disease or with any clinical signs. This type of screening is particularly challenging because mild disease may be difficult to differentiate from a normal phenotype, and the margin for error is small, with potentially major consequences for the breeder. This article reviews HCM screening methods, with particular emphasis on echocardiography.

  8. Turbulence in quantum fluids

    NASA Astrophysics Data System (ADS)

    Tsubota, Makoto

    2014-02-01

    This paper reviews briefly the recent important developments in the physics of quantum turbulence (QT) in superfluid helium and atomic Bose-Einstein condensates (BECs). After giving the basics of quantum hydrodynamics, we discuss energy spectrum, QT created by vibrating structures, and visualization among the topics on superfluid helium. For atomic BECs we review three-dimensional QT, two-component BECs, and spin turbulence in spinor BECs. The last part is devoted to some perspectives of this issue.

  9. Effects of hypercapnia on variability of normal respiratory behavior in awake cats.

    PubMed

    Szlyk, P C; Jennings, D B

    1987-03-01

    Resting quiet awake cats breathing air in a steady state have a range of respiratory behavior, and this encompasses nonpurring and purring (D. B. Jennings and P. C. Szlyk, Can. J. Physiol. Pharmacol. 63: 148-154, 1985). On a given study day, individual cats usually breathed in a limited part of their potential respiratory range. Respiratory pattern, such as average breath frequency (f) and average tidal volume (VT) utilized for a given level of ventilation (V), could be predicted when cats breathed air; as well, inspiratory (TI) and expiratory (TE) times were specific for a given breath f. Inhalation of 2% and 4% CO2 in air caused an average increase in ventilation of 16 and 100%, respectively but breath-to-breath variability of V, f, and VT persisted at each fractional concentration of inspired CO2 (FICO2). The range of different V utilized breath to breath when breathing 2% CO2 overlapped with V during air control studies. Substantial overlap with control V also occurred in three of six cats when breathing 4% CO2. The most consistent effect of progressive hypercapnia was to increase VT and decrease f at a given level of V; increase in V during hypercapnia was accounted for by an increase in mean inspiratory flow (VT/TI). Hypercapnia also caused the fraction of breathing cycle devoted to inspiration (TI/TT) to increase at low f but not at high f.

  10. Perturbing turbulence beyond collapse

    NASA Astrophysics Data System (ADS)

    Kühnen, Jakob; Scarselli, Davide; Hof, Björn; Nonlinear Dynamics; Turbulence Group Team

    2016-11-01

    Wall-bounded turbulent flows are considered to be in principle stable against perturbations and persist as long as the Reynolds number is sufficiently high. We show for the example of pipe flow that a specific perturbation of the turbulent flow field disrupts the genesis of new turbulence at the wall. This leads to an immediate collapse of the turbulent flow and causes complete relaminarisation further downstream. The annihilation of turbulence is effected by a steady manipulation of the streamwise velocity component only, greatly simplifying control efforts which usually require knowledge of the highly complex three dimensional and time dependent velocity fields. We present several different control schemes from laboratory experiments which achieve the required perturbation of the flow for total relaminarisation. Transient growth, a linear amplification mechanism measuring the efficiency of eddies in redistributing shear that quantifies the maximum perturbation energy amplification achievable over a finite time in a linearized framework, is shown to set a clear-cut threshold below which turbulence is impeded in its formation and thus permanently annihilated.

  11. Anisotropic Particles in Turbulence

    NASA Astrophysics Data System (ADS)

    Voth, Greg A.; Soldati, Alfredo

    2017-01-01

    Anisotropic particles are common in many industrial and natural turbulent flows. When these particles are small and neutrally buoyant, they follow Lagrangian trajectories while exhibiting rich orientational dynamics from the coupling of their rotation to the velocity gradients of the turbulence field. This system has proven to be a fascinating application of the fundamental properties of velocity gradients in turbulence. When particles are not neutrally buoyant, they experience preferential concentration and very different preferential alignment than neutrally buoyant tracer particles. A vast proportion of the parameter range of anisotropic particles in turbulence is still unexplored, with most existing research focusing on the simple foundational cases of axisymmetric ellipsoids at low concentrations in homogeneous isotropic turbulence and in turbulent channel flow. Numerical simulations and experiments have recently developed a fairly comprehensive picture of alignment and rotation in these cases, and they provide an essential foundation for addressing more complex problems of practical importance. Macroscopic effects of nonspherical particle dynamics include preferential concentration in coherent structures and drag reduction by fiber suspensions. We review the models used to describe nonspherical particle motion, along with numerical and experimental methods for measuring particle dynamics.

  12. Water transport in limestone by X-ray CAT scanning

    USGS Publications Warehouse

    Mossoti, Victor G.; Castanier, Louis M.

    1989-01-01

    The transport of water through the interior of Salem limestone test briquettes can be dynamically monitored by computer aided tomography (commonly called CAT scanning in medical diagnostics). Most significantly, unless evaporation from a particular face of the briquette is accelerated by forced air flow (wind simulation), the distribution of water in the interior of the briquette remains more or less uniform throughout the complete drying cycle. Moreover, simulated solar illumination of the test briquette does not result in the production of significant water gradients in the briquette under steady-state drying conditions.

  13. Proteinuria in dogs and cats

    PubMed Central

    Harley, Leyenda; Langston, Cathy

    2012-01-01

    Proteinuria is defined as the presence of protein in the urine. Normally, circulating serum proteins are blocked by the glomerulus due to size and/or charge. Any small proteins that pass through a healthy glomerulus are reabsorbed by the renal tubules or broken down by renal tubular epithelial cells. Persistent proteinuria, in the absence of lower urinary tract disease or reproductive tract disease, is usually an indication of renal damage or dysfunction. Less commonly persistent proteinuria can be caused by increased circulating levels of low molecular weight proteins. This article reviews mechanisms of proteinuria in dogs and cats and discusses the importance of screening for and ultimately treating proteinuria. PMID:23204582

  14. BASINs 4.0 Climate Assessment Tool (CAT): Supporting ...

    EPA Pesticide Factsheets

    EPA announced the availability of the report, BASINS 4.0 Climate Assessment Tool (CAT): Supporting Documentation and User's Manual. This report was prepared by the EPA's Global Change Research Program (GCRP), an assessment-oriented program, that sits within the Office of Research and Development, that focuses on assessing how potential changes in climate and other global environmental stressors may impact water quality, air quality, aquatic ecosystems, and human health in the United States. The Program’s focus on water quality is consistent with the Research Strategy of the U.S. Climate Change Research Program—the federal umbrella organization for climate change science in the U.S. government—and is responsive to U.S. EPA’s mission and responsibilities as defined by the Clean Water Act and the Safe Drinking Water Act. A central goal of the EPA GCRP is to provide EPA program offices, Regions, and other stakeholders with tools and information for assessing and responding to any potential future impacts of climate change. In 2007, the EPA Global Change Research Program (GCRP), in partnership with the EPA Office of Water, supported development of a Climate Assessment Tool (CAT) for version 4 of EPA’s BASINS modeling system. This report provides supporting documentation and user support materials for the BASINS CAT tool. The purpose of this report is to provide in a single document a variety of documentation and user support materials supporting the use

  15. A Baroclinic Model of turbulent dusty flows

    SciTech Connect

    Kuhl, A.L.

    1992-04-01

    The problem considered here is the numerical simulation of the turbulent dusty flow induced by explosions over soil surfaces. Some of the unresolved issues are: (1) how much dust is scoured from such surfaces; (2) where does the dust go in the boundary layer; (3) what is the dusty boundary layer height versus time; (4) what are the dusty boundary layer profiles; (5) how much of the dust mass becomes entrained into the dust stem; and (6) where does the dust go in the buoyant cloud? The author proposes a Baroclinic Model for flows with large density variations that actually calculates the turbulent mixing and transport of dust on an adaptive grid. The model is based on the following idealizations: (1) a loose dust bed; (2) an instantaneous shock fluidization of the dust layer; (3) the dust and air are in local equilibrium (so air viscosity enforces the no-slip condition); (4) the dust-air mixture is treated as a continuum dense fluid with zero viscosity; and (5) the turbulent mixing is dominated by baroclinically-generated vorticity. These assumptions lead to an inviscid set of conservation laws for the mixture, which are solved by means of a high-order Godunov algorithm for gasdynamics. Adaptive Mesh Refinement (AMR) is used to capture the turbulent mixing processes on the grid. One of the unique characteristics of these flows is that mixing occurs because vorticity is produced by an inviscid, baroclinic mechanism. A number of examples are presented to illustrate these baroclinic effects including shock interactions with dense-gas layers and dust beds, and dusty wall jets of airblast precursors. The conclusion of these studies is that dusty boundary layers grow because of mass entrainment from the fluidized bed (and not because of viscous wall drag) as proven by the Mass Integral Equation.

  16. Respiratory nematodes in cat populations of Italy.

    PubMed

    Di Cesare, Angela; Veronesi, Fabrizia; Grillotti, Eleonora; Manzocchi, Simone; Perrucci, Stefania; Beraldo, Paola; Cazzin, Stefania; De Liberato, Claudio; Barros, Luciano A; Simonato, Giulia; Traversa, Donato

    2015-12-01

    The occurrence of common respiratory parasites of domestic cats (the metastrongyloid "cat lungworm" Aelurostrongylus abstrusus and the trichuroid Capillaria aerophila) and of neglected respiratory nematodes of felids (Troglostrongylus brevior, Angiostrongylus chabaudi and Oslerus rostratus) was here evaluated in two and three geographical sites of Northern and Central Italy, respectively. In 2014-2015, individual fecal samples of 868 domestic cats were examined microscopically and genetically, and epidemiological data related to parasitic infections were evaluated as possible risk factors by binary logistic regression models. The most common parasite was A. abstrusus in both mono- and poli-specific infections, followed by T. brevior and C. aerophila, while cats scored negative for other parasites. Cats positive for A. abstrusus (1.9-17 % infection rate) and C. aerophila (0.9-4.8 % infection rate) were found in all examined sites, while cats scored positive for T. brevior (1-14.3 % infection rate) in four sites. Also, T. brevior was here found for the first time in a domestic cat from a mountainous area of Northern Italy. The occurrence of lungworms was statistically related to the presence of respiratory signs and more significant in cats with mixed infection by other lungworms and/or intestinal parasites. Cats living in site C of Central Italy resulted statistically more at risk of infection for lungworms than cats living in the other study sites, while animals ageing less than 1 year were at more risk for troglostrongylosis. Finally, the presence of lungworms was more significant in cats with mixed infection by other lungworms and/or intestinal parasites. These results are discussed under epidemiological and clinical points of views.

  17. Reconciling actual and perceived rates of predation by domestic cats.

    PubMed

    McDonald, Jennifer L; Maclean, Mairead; Evans, Matthew R; Hodgson, Dave J

    2015-07-01

    The predation of wildlife by domestic cats (Felis catus) is a complex problem: Cats are popular companion animals in modern society but are also acknowledged predators of birds, herpetofauna, invertebrates, and small mammals. A comprehensive understanding of this conservation issue demands an understanding of both the ecological consequence of owning a domestic cat and the attitudes of cat owners. Here, we determine whether cat owners are aware of the predatory behavior of their cats, using data collected from 86 cats in two UK villages. We examine whether the amount of prey their cat returns influences the attitudes of 45 cat owners toward the broader issue of domestic cat predation. We also contribute to the wider understanding of physiological, spatial, and behavioral drivers of prey returns among cats. We find an association between actual prey returns and owner predictions at the coarse scale of predatory/nonpredatory behavior, but no correlation between the observed and predicted prey-return rates among predatory cats. Cat owners generally disagreed with the statement that cats are harmful to wildlife, and disfavored all mitigation options apart from neutering. These attitudes were uncorrelated with the predatory behavior of their cats. Cat owners failed to perceive the magnitude of their cats' impacts on wildlife and were not influenced by ecological information. Management options for the mitigation of cat predation appear unlikely to work if they focus on "predation awareness" campaigns or restrictions of cat freedom.

  18. Temperature and species-concentration measurements in turbulent flames by the CARS technique

    SciTech Connect

    Goss, L.P.; Schreiber, P.W.; Switzer, G.L.; Trump, D.D.

    1983-09-01

    Simultaneous temperature and N/sub 2/-concentration data have been obtained employing a 10-Hz coherent anti-stokes Raman spectroscopy system on two propane-air turbulent-jet diffusion flames with Reynolds numbers of 2000 and 6000. Average values, probability density functions, and correlation plots show reasonable trends for both centerline and radial profiles of the turbulent flames.

  19. Sparse spectrum model for a turbulent phase.

    PubMed

    Charnotskii, Mikhail

    2013-03-01

    Monte Carlo (MC) simulation of phase front perturbations by atmospheric turbulence finds numerous applications for design and modeling of the adaptive optics systems, laser beam propagation simulations, and evaluating the performance of the various optical systems operating in the open air environment. Accurate generation of two-dimensional random fields of turbulent phase is complicated by the enormous diversity of scales that can reach five orders of magnitude in each coordinate. In addition there is a need for generation of the long "ribbons" of turbulent phase that are used to represent the time evolution of the wave front. This makes it unfeasible to use the standard discrete Fourier transform-based technique as a basis for the MC simulation algorithm. We propose a new model for turbulent phase: the sparse spectrum (SS) random field. The principal assumption of the SS model is that each realization of the random field has a discrete random spectral support. Statistics of the random amplitudes and wave vectors of the SS model are arranged to provide the required spectral and correlation properties of the random field. The SS-based MC model offers substantial reduction of computer costs for simulation of the wide-band random fields and processes, and is capable of generating long aperiodic phase "ribbons." We report the results of model trials that determine the number of sparse components, and the range of wavenumbers that is necessary to accurately reproduce the random field with a power-law spectrum.

  20. Chaotic radiation/turbulence interactions in flames

    SciTech Connect

    Menguec, M.P.; McDonough, J.M.

    1998-11-01

    In this paper, the authors present a review of their recent efforts to model chaotic radiation-turbulence interactions in flames. The main focus is to characterize soot volume fraction fluctuations in turbulent diffusion flames, as they strongly contribute to these interaction. The approach is based on the hypothesis that the fluctuations of properties in turbulent flames are deterministic in nature, rather than random. The authors first discuss the theoretical details and then they briefly outline the experiments conducted to measure the scattered light signals from fluctuating soot particles along the axis of an ethylene-air diffusion flame. They compare the power spectra and time series obtained from experiments against the ad-hoc and rigorous models derived using a series of logistic maps. These logistic maps can be used in simulation of the fluctuations in these type of flames, without extensive computational effort or sacrifice of physical detail. Availability of accurate models of these kinds allows investigation of radiation-turbulence interactions at a more fundamental level than it was previously possible.

  1. Turbulence assessment at potential turbine sites

    SciTech Connect

    Daniels, A.

    1996-12-31

    As opposed to a fixed anemometer, the Tala kite is free to move in the air. The motion of the kite is not random, it moves with or against the speed gradient towards the center of passing turbulence events of higher or lower speeds thus allowing the kite to measure event maximum or minimum speed rather than the speed at some unknown distance from the event center like a fixed anemometer. This behavior is confirmed both by a theoretical aerodynamics analysis of the kite motion and by data from a field study where kite and hot film anemometer (HFA) events, defined by the rain flow count method, were compared with flap events on a rotating turbine blade. The HFAs simulated too few events lasting too long while the kites reproduced both the number of events and event periods remarkably close. It is concluded that the kite is the optimal tool for measuring turbulence at potential turbine sites. Kite turbulence can form the bases for economic return estimates and an example is given where less windy sites could be more economical than other more turbulent higher speed sites. 13 refs., 8 figs.

  2. Numerical simulation of premixed turbulent methane combustion

    SciTech Connect

    Day, Marc S.; Bell, John B.; Almgren, Ann S.; Beckner, Vincent E.; Lijewski, Michael J.; Cheng, Robert; Shepherd, Ian; Johnson, Matthew

    2003-06-14

    With adaptive-grid computational methodologies and judicious use of compressible and low Mach number combustion models, we are carrying out three-dimensional, time-dependent direct numerical simulations of a laboratory-scale turbulent premixed methane burner. In the laboratory experiment, turbulence is generated by a grid located in the throat of a 50mm diameter circular nozzle; swirl is be introduced by four tangential air jets spaced uniformly around the circumference of the nozzle just above the turbulence grid. A premixed methane flame is stabilized above the nozzle in the central core region where a velocity deficit is induced7the swirling flow. The time-dependent flow field inside the nozzle, from the turbulence grid and the high-speed jets, to the nozzle exit plane is simulated using an adaptive-grid embedded-boundary compressible Navier-Stokes solver. The compressible calculation then provides time-dependent boundary conditions for an adaptive low Mach number model of the swirl-stabilized premixed flame. The low Mach model incorporates detailed chemical kinetics and species transport using 20 species and 84 reactions. Laboratory diagnostics available for comparisons include characterizations of the flow field just down stream of the nozzle exit plane, and flame surface statistics, such as mean location, wrinkling and crossing frequencies.

  3. Unsteady turbulence cascades.

    PubMed

    Goto, Susumu; Vassilicos, J C

    2016-11-01

    We have run a total of 311 direct numerical simulations (DNSs) of decaying three-dimensional Navier-Stokes turbulence in a periodic box with values of the Taylor length-based Reynolds number up to about 300 and an energy spectrum with a wide wave-number range of close to -5/3 power-law dependence at the higher Reynolds numbers. On the basis of these runs, we have found a critical time when (i) the rate of change of the square of the integral length scale turns from increasing to decreasing, (ii) the ratio of interscale energy flux to high-pass filtered turbulence dissipation changes from decreasing to very slowly increasing in the inertial range, (iii) the signature of large-scale coherent structures disappears in the energy spectrum, and (iv) the scaling of the turbulence dissipation changes from the one recently discovered in DNSs of forced unsteady turbulence and in wind tunnel experiments of turbulent wakes and grid-generated turbulence to the classical scaling proposed by G. I. Taylor [Proc. R. Soc. London, Ser. A 151, 421 (1935)1364-502110.1098/rspa.1935.0158] and A. N. Kolmogorov [Dokl. Akad. Nauk SSSR 31, 538 (1941)]. Even though the customary theoretical basis for this Taylor-Kolmogorov scaling is a statistically stationary cascade where large-scale energy flux balances dissipation, this is not the case throughout the entire time range of integration in all our DNS runs. The recently discovered dissipation scaling can be reformulated physically as a situation in which the dissipation rates of the small and large scales evolve together. We advance two hypotheses that may form the basis of a theoretical approach to unsteady turbulence cascades in the presence of large-scale coherent structures.

  4. Unsteady turbulence cascades

    NASA Astrophysics Data System (ADS)

    Goto, Susumu; Vassilicos, J. C.

    2016-11-01

    We have run a total of 311 direct numerical simulations (DNSs) of decaying three-dimensional Navier-Stokes turbulence in a periodic box with values of the Taylor length-based Reynolds number up to about 300 and an energy spectrum with a wide wave-number range of close to -5 /3 power-law dependence at the higher Reynolds numbers. On the basis of these runs, we have found a critical time when (i) the rate of change of the square of the integral length scale turns from increasing to decreasing, (ii) the ratio of interscale energy flux to high-pass filtered turbulence dissipation changes from decreasing to very slowly increasing in the inertial range, (iii) the signature of large-scale coherent structures disappears in the energy spectrum, and (iv) the scaling of the turbulence dissipation changes from the one recently discovered in DNSs of forced unsteady turbulence and in wind tunnel experiments of turbulent wakes and grid-generated turbulence to the classical scaling proposed by G. I. Taylor [Proc. R. Soc. London, Ser. A 151, 421 (1935), 10.1098/rspa.1935.0158] and A. N. Kolmogorov [Dokl. Akad. Nauk SSSR 31, 538 (1941)]. Even though the customary theoretical basis for this Taylor-Kolmogorov scaling is a statistically stationary cascade where large-scale energy flux balances dissipation, this is not the case throughout the entire time range of integration in all our DNS runs. The recently discovered dissipation scaling can be reformulated physically as a situation in which the dissipation rates of the small and large scales evolve together. We advance two hypotheses that may form the basis of a theoretical approach to unsteady turbulence cascades in the presence of large-scale coherent structures.

  5. Chronic progressive polyarthritis in a female cat.

    PubMed

    Oohashi, Eiji; Yamada, Kazutaka; Oohashi, Mirai; Ueda, Junji

    2010-04-01

    Feline chronic progressive polyarthritis is a rare immune-mediated disease that has only previously been reported in male cats. A one-year-old female cat was presented with anorexia, lassitude and lameness. The tarsal, carpal and elbow joints revealed swelling, pain, stiffness, crepitus and regional lymphadenopathy, and fever was present. The cat was clinically diagnosed with chronic progressive polyarthritis based on the fever, swelling of joints, imaging of erosive proliferative periosteal polyarthritis, positivity for antinuclear antibody, synovial fluid analyses and urinalyses. Both feline leukemia virus antigen and feline immunodeficiency virus antibody were positive. Using hair root DNA, polymerase chain reaction amplification targeting the sex-determining region on the Y chromosome gene amplified the fragment of DNA from a normal male cat, but not amplified from a normal female cat or the present cat. Accordingly, the present cat was classified as genetically female. Cyclosporine treatment was started, and the general condition and movement quickly improved and continued for 8 months post-diagnosis. This is the first report of chronic progressive polyarthritis in a female cat.

  6. Cloud-Aerosol Transport System (CATS)

    Atmospheric Science Data Center

    2015-03-05

    ... observing platform. CATS provides in-space demonstration of technologies for future satellite missions while demonstrating build-to-cost ... (CPL) on the ER-2 on Feb 10, 17, 20 and 21. For more information, please see the CATS homepage  or the attached  presentation ...

  7. Malassezia spp. overgrowth in allergic cats.

    PubMed

    Ordeix, Laura; Galeotti, Franca; Scarampella, Fabia; Dedola, Carla; Bardagí, Mar; Romano, Erica; Fondati, Alessandra

    2007-10-01

    A series of 18 allergic cats with multifocal Malassezia spp. overgrowth is reported: atopic dermatitis was diagnosed in 16, an adverse food reaction in another and one was euthanized 2 months after diagnosis of Malassezia overgrowth. All the cats were otherwise healthy and those tested (16 out of 18) for feline leukaemia or feline immunodeficiency virus infections were all negative. At dermatological examination, multifocal alopecia, erythema, crusting and greasy adherent brownish scales were variably distributed on all cats. Cytological examination revealed Malassezia spp. overgrowth with/without bacterial infection in facial skin (n = 11), ventral neck (n = 6), abdomen (n = 6), ear canal (n = 4), chin (n = 2), ear pinnae (n = 2), interdigital (n = 1) and claw folds skin (n = 1). Moreover, in two cats Malassezia pachydermatis was isolated in fungal cultures from lesional skin. Azoles therapy alone was prescribed in seven, azoles and antibacterial therapy in eight and azoles with both antibacterial and anti-inflammatory therapy in three of the cats. After 3-4 weeks of treatment, substantial reduction of pruritus and skin lesions was observed in all 11 cats treated with a combined therapy and in five of seven treated solely with azoles. Malassezia spp. overgrowth may represent a secondary cutaneous problem in allergic cats particularly in those presented for dermatological examination displaying greasy adherent brownish scales. The favourable response to treatment with antifungal treatments alone suggests that, as in dogs, Malassezia spp. may be partly responsible for both pruritus and cutaneous lesions in allergic cats.

  8. Cool Cats: Feline Fun with Abstract Art.

    ERIC Educational Resources Information Center

    Lambert, Phyllis Gilchrist

    2002-01-01

    Presents a lesson that teaches students about abstract art in a fun way. Explains that students draw cats, learn about the work of Pablo Picasso, and, in the style of Picasso, combine the parts of the cats (tail, legs, head, body) together in unconventional ways. (CMK)

  9. Dirofilaria immitis in cats: diagnosis and management.

    PubMed

    Nelson, C Thomas

    2008-07-01

    Imaging and laboratory studies can help with the diagnosis of heartworm disease in cats, but no test is definitive. Furthermore, even when the diagnosis can be reliably established, therapy directed at the heartworms does little to help the cat. Rather, management is directed at alleviating clinical signs, with an emphasis on prevention for all.

  10. Quantum Computer Games: Schrodinger Cat and Hounds

    ERIC Educational Resources Information Center

    Gordon, Michal; Gordon, Goren

    2012-01-01

    The quantum computer game "Schrodinger cat and hounds" is the quantum extension of the well-known classical game fox and hounds. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. "Schrodinger cat and hounds" demonstrates the effects of superposition, destructive and constructive interference, measurements and…

  11. Bradyarrhythmia in an anaesthetised, elderly, hypertensive cat.

    PubMed

    Ticehurst, Kim; Zaki, Sanaa; Maddern, Kieren; Lingard, Amy; Barrs, Vanessa; Malik, Richard

    2007-12-01

    A 14-year-old neutered male domestic shorthaired cat was presented to the University Veterinary Centre Sydney for evaluation and treatment of dental disease. This cat developed an unusual bradyarrhythmia under anaesthesia. The possible causes and treatment of the dysrythmia are discussed.

  12. Disseminated Mycobacterium avium infection in a cat

    PubMed Central

    Barry, Maureen; Taylor, Judith; Woods, Paul

    2002-01-01

    A domestic shorthair cat was presented for lethargy and ataxia. Clinical findings included an abdominal mass, lumbosacral pain, ataxia. Aspirates from the liver and lymph nodes revealed intracellular, negative-staining rods. Treatment for presumptive mycobacterium infection was unsuccessful and the cat was euthanized. Disseminated Mycobacterium avium was confirmed on culture. PMID:12001504

  13. Atmospheric turbulence induced synthetic aperture lidar phase error compensation

    NASA Astrophysics Data System (ADS)

    Lu, Tian-an; Li, Hong-ping

    2016-12-01

    The resolution of a conventional optical imaging radar system is constrained by the diffraction limit of the telescope's aperture. The combination of lidar and synthetic aperture processing techniques can overcome the diffraction limit and provide a higher resolution air borne remote sensor. Atmospheric turbulence is an important factor affecting lidar imaging, and the phase screen simulation method is an effective method to simulate the degradation of laser signal propagating through turbulent atmosphere. By using Monte-Carlo random factor, the randomness of phase screens can be improved. The lidar imaging with different turbulence intensity is also calculated in this paper, then the improved rank one phase estimation autofocus method is used to compensate the imaging phase errors. The results show that the method of generating phase screen is consistent with the statistics of atmospheric turbulence, which can well simulate the effect of atmospheric turbulence on synthetic aperture lidar, and the influence on synthetic aperture lidar azimuth resolution is greater when atmospheric turbulence is stronger. Improved rank one phase estimation algorithm has good autofocus effect, which can effectively compensate the phase errors and enhance the image quality degraded by turbulence.

  14. Connecting exact coherent states to turbulent dynamics in channel flow

    NASA Astrophysics Data System (ADS)

    Park, Jae Sung; Graham, Michael D.

    2015-11-01

    The discovery of nonlinear traveling wave solutions to the Navier-Stokes equations or exact coherent states has greatly advanced the understanding of the nature of turbulent shear flows. These solutions are unstable saddle points in state space, while the time evolution of a turbulent flow is a dynamical trajectory wandering around them. In this regard, it is of interest to investigate how closely the turbulent trajectories approach these invariant states. Here, we present connections between turbulent trajectories and one intriguing solution family in channel flow. A state space visualization of turbulent trajectories is presented in a three-dimensional space. The lifetime of the trajectories is well represented by closeness to two distinct solutions resembling in many ways the active and hibernating phases of minimal channel turbulence (Xi & Graham PRL 2010). The connections are then examined by comparing mean profiles and flow structures. More importantly, the connections are confirmed by calculating the L2 distance between the trajectories and the traveling waves. Lastly, paths of an intermittent bursting phenomenon are identified in state space and the relationship between bursting paths and the traveling waves or hibernating turbulence is further discussed. This work was supported by the Air Force Office of Scientific Research through grant FA9550-15-1-0062 (Flow Interactions and Control Program).

  15. Laboratory simulation of atmospheric turbulence-induced optical wavefront distortion

    NASA Astrophysics Data System (ADS)

    Taylor, Travis S.; Gregory, Don A.

    2002-11-01

    Real-time liquid crystal television-based technique for simulating optical wavefront distortion due to atmospheric turbulence is presented and demonstrated. A liquid crystal television (LCTV) operating in the "phase mostly" mode was used as an array of spatially correlated phase delays. A movie of the arrays in motion was then generated and displayed on the LCTV. The turbulence simulation system was verified by passing a collimated and doubled diode pumped Nd:YVO 4 laser beam (532 nm) through the transparent LCTV screen. The beam was then passed through a lens and the power spectra of the turbulence information carrying beam was detected as a measure of the far-field distribution. The same collimated laser beam, without the LCTV, was also transmitted down an open-air range and the power spectra detected as a measure of a real far-field distribution. Accepted turbulence parameters were measured for both arrangements and then compared.

  16. A model for reaction rates in turbulent reacting flows

    NASA Technical Reports Server (NTRS)

    Chinitz, W.; Evans, J. S.

    1984-01-01

    To account for the turbulent temperature and species-concentration fluctuations, a model is presented on the effects of chemical reaction rates in computer analyses of turbulent reacting flows. The model results in two parameters which multiply the terms in the reaction-rate equations. For these two parameters, graphs are presented as functions of the mean values and intensity of the turbulent fluctuations of the temperature and species concentrations. These graphs will facilitate incorporation of the model into existing computer programs which describe turbulent reacting flows. When the model was used in a two-dimensional parabolic-flow computer code to predict the behavior of an experimental, supersonic hydrogen jet burning in air, some improvement in agreement with the experimental data was obtained in the far field in the region near the jet centerline. Recommendations are included for further improvement of the model and for additional comparisons with experimental data.

  17. Drizzle formation in stratocumulus clouds: Effects of turbulent mixing

    SciTech Connect

    Magaritz-Ronen, L.; Pinsky, M.; Khain, A.

    2016-02-17

    The mechanism of drizzle formation in shallow stratocumulus clouds and the effect of turbulent mixing on this process are investigated. A Lagrangian–Eularian model of the cloud-topped boundary layer is used to simulate the cloud measured during flight RF07 of the DYCOMS-II field experiment. The model contains ~ 2000 air parcels that are advected in a turbulence-like velocity field. In the model all microphysical processes are described for each Lagrangian air volume, and turbulent mixing between the parcels is also taken into account. It was found that the first large drops form in air volumes that are closest to adiabatic and characterized by high humidity, extended residence near cloud top, and maximum values of liquid water content, allowing the formation of drops as a result of efficient collisions. The first large drops form near cloud top and initiate drizzle formation in the cloud. Drizzle is developed only when turbulent mixing of parcels is included in the model. Without mixing, the cloud structure is extremely inhomogeneous and the few large drops that do form in the cloud evaporate during their sedimentation. Lastly, it was found that turbulent mixing can delay the process of drizzle initiation but is essential for the further development of drizzle in the cloud.

  18. Drizzle formation in stratocumulus clouds: Effects of turbulent mixing

    DOE PAGES

    Magaritz-Ronen, L.; Pinsky, M.; Khain, A.

    2016-02-17

    The mechanism of drizzle formation in shallow stratocumulus clouds and the effect of turbulent mixing on this process are investigated. A Lagrangian–Eularian model of the cloud-topped boundary layer is used to simulate the cloud measured during flight RF07 of the DYCOMS-II field experiment. The model contains ~ 2000 air parcels that are advected in a turbulence-like velocity field. In the model all microphysical processes are described for each Lagrangian air volume, and turbulent mixing between the parcels is also taken into account. It was found that the first large drops form in air volumes that are closest to adiabatic andmore » characterized by high humidity, extended residence near cloud top, and maximum values of liquid water content, allowing the formation of drops as a result of efficient collisions. The first large drops form near cloud top and initiate drizzle formation in the cloud. Drizzle is developed only when turbulent mixing of parcels is included in the model. Without mixing, the cloud structure is extremely inhomogeneous and the few large drops that do form in the cloud evaporate during their sedimentation. Lastly, it was found that turbulent mixing can delay the process of drizzle initiation but is essential for the further development of drizzle in the cloud.« less

  19. Exocrine pancreatic insufficiency in the cat.

    PubMed

    Steiner, Jörg M

    2012-08-01

    Exocrine pancreatic insufficiency (EPI) is a syndrome caused by an insufficient amount of pancreatic digestive enzymes in the small intestine. Clinical signs most commonly reported in cats with EPI are weight loss, loose and voluminous stools, steatorrhea, polyphagia, and in some cases a greasy soiling of the hair coat in the perianal region. Serum feline trypsin-like immunoreactivity concentration is the diagnostic test of choice for the diagnosis of affected cats. Treatment of cats with EPI consists of enzyme supplementation with either a powdered pancreatic extract or raw pancreas. Most cats with EPI also have severely decreased serum cobalamin concentrations and may require lifelong parenteral cobalamin supplementation. Most cats respond well to therapy and can have a normal life expectancy and quality of life.

  20. The Near Eastern origin of cat domestication.

    PubMed

    Driscoll, Carlos A; Menotti-Raymond, Marilyn; Roca, Alfred L; Hupe, Karsten; Johnson, Warren E; Geffen, Eli; Harley, Eric H; Delibes, Miguel; Pontier, Dominique; Kitchener, Andrew C; Yamaguchi, Nobuyuki; O'brien, Stephen J; Macdonald, David W

    2007-07-27

    The world's domestic cats carry patterns of sequence variation in their genome that reflect a history of domestication and breed development. A genetic assessment of 979 domestic cats and their wild progenitors-Felis silvestris silvestris (European wildcat), F. s. lybica (Near Eastern wildcat), F. s. ornata (central Asian wildcat), F. s. cafra (southern African wildcat), and F. s. bieti (Chinese desert cat)-indicated that each wild group represents a distinctive subspecies of Felis silvestris. Further analysis revealed that cats were domesticated in the Near East, probably coincident with agricultural village development in the Fertile Crescent. Domestic cats derive from at least five founders from across this region, whose descendants were transported across the world by human assistance.

  1. Polycystic kidney disease in a Chartreux cat.

    PubMed

    Volta, Antonella; Manfredi, Sabrina; Gnudi, Giacomo; Gelati, Aldo; Bertoni, Giorgio

    2010-02-01

    Polycystic kidney disease (PKD) is one of the most common genetic diseases in cats. It has been widely described in Persians and Persian-related cats and sporadically in other breeds. The purpose of the present paper is to describe the first reported case of PKD in a 12-year-old female Chartreux cat. The cat was referred with polyuria and polydipsia and enlarged and irregular kidneys at palpation. Multiple renal cysts and a single liver cyst were identified by ultrasound and the inherited pattern was confirmed by genetic test (polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) assay). Chartreux cats should be included in the screening programme of PKD, and PKD should be always considered as a possible cause of chronic renal failure in this breed.

  2. Laminar boundary layer in conditions of natural transition to turbulent flow

    NASA Technical Reports Server (NTRS)

    Polyakov, N. F.

    1986-01-01

    Results of experimental study of regularities of a natural transition of a laminar boundary layer to a turbulent layer at low subsonic air flow velocities are presented, analyzed and compared with theory and model experiments.

  3. Linearly Forced Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Lundgren, T. S.

    2003-01-01

    Stationary isotropic turbulence is often studied numerically by adding a forcing term to the Navier-Stokes equation. This is usually done for the purpose of achieving higher Reynolds number and longer statistics than is possible for isotropic decaying turbulence. It is generally accepted that forcing the Navier-Stokes equation at low wave number does not influence the small scale statistics of the flow provided that there is wide separation between the largest and smallest scales. It will be shown, however, that the spectral width of the forcing has a noticeable effect on inertial range statistics. A case will be made here for using a broader form of forcing in order to compare computed isotropic stationary turbulence with (decaying) grid turbulence. It is shown that using a forcing function which is directly proportional to the velocity has physical meaning and gives results which are closer to both homogeneous and non-homogeneous turbulence. Section 1 presents a four part series of motivations for linear forcing. Section 2 puts linear forcing to a numerical test with a pseudospectral computation.

  4. Gyrokinetic turbulent heating

    SciTech Connect

    Hinton, F. L.; Waltz, R. E.

    2006-10-15

    Expressions for particle and energy fluxes and heating rates due to turbulence are derived. These fluxes and heating rates are identified from moments of an extended drift-kinetic equation for the equilibrium distribution function. These include neoclassical as well as turbulent diffusion and heating. Phase-space conservation is demonstrated, allowing the drift-kinetic equation to be expressed in conservative form. This facilitates taking moments with few approximations, mainly those consistent with drift kinetics for the equilibrium distribution function and the relative smallness of the fluctuations. The turbulent heating is uniquely defined by choosing the standard gyrokinetic definition for the energy flux. With this definition, most of the heating can be expressed in the form of ohmic heating from turbulent parallel and perpendicular current density perturbations. The latter current is identified with grad-B and curvature drifts, plus terms involving magnetic perturbations (which are smaller for low beta). A small contribution to the heating comes from the divergence of an energy flux that is dependent on the finite gyroradius of the ions. The fluxes and heating rates are expressed in a form that can be easily evaluated from gyrokinetic turbulence simulations.

  5. Phenomenology of turbulent convection

    NASA Astrophysics Data System (ADS)

    Verma, Mahendra; Chatterjee, Anando; Kumar, Abhishek; Samtaney, Ravi

    2016-11-01

    We simulate Rayleigh-Bénard convection (RBC) in which a fluid is confined between two thermally conducting plates. We report results from direct numerical simulation (DNS) of RBC turbulence on 40963 grid, the highest resolution hitherto reported, on 65536 cores of Cray XC40, Shaheen II, at KAUST. The non-dimensional parameters of our simulation are: the Rayleigh number Ra = 1 . 1 ×1011 (the highest ever for a pseudo-spectral simulation) and Prandtl number of unity. We present energy flux diagnostics of shell-to-shell (in wave number space) transfer. Furthermore, noting that convective flows are anisotropic due to buoyancy, we quantify anisotropy by subdividing each wavenumber shell into rings and quantify ring energy spectrum. An outstanding question in convective turbulence is the wavenumber scaling of the energy spectrum. Our pseudo-spectral simulations of turbulent thermal convection coupled with novel energy transfer diagnostics have provided a definitive answer to this question. We conclude that convective turbulence exhibits behavior similar to fluid turbulence, that is, Kolmogorov's k - 5 / 3 spectrum with forward and local energy transfers, along with a nearly isotropic energy distribution. The supercomputer Shaheen at KAUST was utilized for the simulations.

  6. Reconciling actual and perceived rates of predation by domestic cats

    PubMed Central

    McDonald, Jennifer L; Maclean, Mairead; Evans, Matthew R; Hodgson, Dave J

    2015-01-01

    The predation of wildlife by domestic cats (Felis catus) is a complex problem: Cats are popular companion animals in modern society but are also acknowledged predators of birds, herpetofauna, invertebrates, and small mammals. A comprehensive understanding of this conservation issue demands an understanding of both the ecological consequence of owning a domestic cat and the attitudes of cat owners. Here, we determine whether cat owners are aware of the predatory behavior of their cats, using data collected from 86 cats in two UK villages. We examine whether the amount of prey their cat returns influences the attitudes of 45 cat owners toward the broader issue of domestic cat predation. We also contribute to the wider understanding of physiological, spatial, and behavioral drivers of prey returns among cats. We find an association between actual prey returns and owner predictions at the coarse scale of predatory/nonpredatory behavior, but no correlation between the observed and predicted prey-return rates among predatory cats. Cat owners generally disagreed with the statement that cats are harmful to wildlife, and disfavored all mitigation options apart from neutering. These attitudes were uncorrelated with the predatory behavior of their cats. Cat owners failed to perceive the magnitude of their cats’ impacts on wildlife and were not influenced by ecological information. Management options for the mitigation of cat predation appear unlikely to work if they focus on “predation awareness” campaigns or restrictions of cat freedom. PMID:26306163

  7. Feral Cats: Too Long a Threat to Hawaiian Wildlife

    USGS Publications Warehouse

    Hess, Steven C.; Banko, Paul C.

    2006-01-01

    BACKGROUND Domestic cats (Felis catus) were first brought to Hawai`i aboard sailing ships of European explorers and colonists. The job of these predators was to control mice and rats on the ships during the long voyages. As in other places, cats were taken in and adopted by the families of Hawai`i and soon became household pets known as popoki. But cats have always been very well equipped to live and hunt on their own. On tropical archipelagos like the Hawaiian Islands where no other predatory mammals of comparable size existed, abundant and naive prey were particularly easy game, and cats soon thrived in the wild. Although the details of when cats first came to live in the wild remain little known, adventurers, writers, and naturalists of the day recorded some important observations. Feral cats were observed in remote wilderness around K?ilauea volcano on Hawai`i Island as early as 1840 by explorer William Brackenridge. Mark Twain was so impressed by the great abundance of cats when he visited Honolulu in 1866 that he reported his observations in the Sacramento Union newspaper, which were later reprinted in his book Roughing It: I saw... tame cats, wild cats, singed cats, individual cats, groups of cats, platoons of cats, companies of cats, regiments of cats, armies of cats, multitudes of cats, millions of cats...

  8. Turbulence and fossil turbulence in oceans and lakes

    NASA Astrophysics Data System (ADS)

    Leung, Pak Tao; Gibson, Carl H.

    2013-01-01

    Turbulence is defined as an eddy-like state of fluid motion where the intertial-vortex forces of the eddies are larger than any of the other forces that tend to damp the eddies out. Energy cascades of irrotational flows from large scales to small are non-turbulent, even if they supply energy to turbulence. Turbulent flows are rotational and cascade from small scales to large, with feedback. Viscous forces limit the smallest turbulent eddy size to the Kolmogorov scale. In stratified fluids, buoyancy forces limit large vertical overturns to the Ozmidov scale and convert the largest turbulent eddies into a unique class of saturated, non-propagating, internal waves, termed fossil-vorticity-turbulence. These waves have the same energy but different properties and spectral forms than the original turbulence patch. The Gibson (1980, 1986) theory of fossil turbulence applies universal similarity theories of turbulence and turbulent mixing to the vertical evolution of an isolated patch of turbulence in a stratified fluid as its growth is constrained and fossilized by buoyancy forces. Quantitative hydrodynamic-phase-diagrams (HPDs) from the theory are used to classify microstructure patches according to their hydrodynamic states. When analyzed in HPD space, previously published oceanic datasets showed their dominant microstructure patches are fossilized at large scales in all layers. Laboratory and field measurements suggested phytoplankton species with different swimming abilities adjust their growth strategies by pattern recognition of turbulence-fossil-turbulence dissipation and persistence times that predict survival-relevant surface layer sea changes. New data collected near a Honolulu waste-water outfall showed the small-to-large evolution of oceanic turbulence microstructure from active to fossil states, and revealed the ability of fossil-density-tubulence patches to absorb, and vertically radiate, internal wave energy, information, and enhanced turbulent

  9. New Lidar Capabilities in Space: An Overview of the Cloud-Aerosol Transport System (CATS)

    NASA Astrophysics Data System (ADS)

    McGill, M. J.; Yorks, J. E.; Hlavka, D. L.; Selmer, P. A.; Hart, W. D.; Palm, S. P.; Nowottnick, E. P.; Vaughan, M.; Rodier, S. D.; Colarco, P. R.; da Silva, A.; Buchard, V.

    2014-12-01

    The Cloud-Aerosol Transport System (CATS), built at NASA Goddard Space Flight Center as a payload for the International Space Station (ISS), is set to launch in the late 2014. CATS is an elastic backscatter lidar operating in one of three science modes with three wavelengths (1064, 532, 355 nm) and HSRL capability at 532 nm. Depolarization measurements will be made at the 532 and 1064 nm wavelengths. The CATS science modes are described in Figure 1. The ISS orbit is a 51 degree inclination orbit at an altitude of about 405 km. This orbit provides more comprehensive coverage of the tropics and mid-latitudes than sun-synchronous orbiting sensors, with nearly a three day repeat cycle. Thus, science applications of CATS include cloud and aerosol climate studies, air quality monitoring, and smoke/volcanic plume tracking. Current uncertainties in cloud and aerosol properties limit our ability to accurately model the Earth's climate system and predict climate change. These limitations are due primarily to difficulties in adequately measuring aerosols and clouds on a global scale. A primary science objectives of CATS is to provide global aerosol and cloud vertical profile data in near real time to for assimilation in aerosol transport models such as the NASA GEOS-5 model. Furthermore, the vertical profiles of cloud and aerosol properties provided by CATS will complement current and future passive satellite sensors. Another important science objective of CATS is to advance technology in support of future mission development. CATS will employ 355 nm and HSRL capabilities, as well as depolarization at multiple wavelengths. These expanded measurement capabilities will provide the science community with new and improved global data products that have yet to be retrieved from space-based lidar. In preparation for launch, simulations of the CATS lidar signal are produced using GEOS5 model data to develop and test future data products. An example of the simulated CATS attenuated

  10. Renal morphology in cats with diabetes mellitus.

    PubMed

    Zini, E; Benali, S; Coppola, L; Guscetti, F; Ackermann, M; Lutz, T A; Reusch, C E; Aresu, L

    2014-11-01

    In humans, diabetes mellitus (DM) is an important cause of renal damage, with glomerular lesions being predominant. In cats, although diabetes is a common endocrinopathy, it is yet unknown whether it leads to renal damage. The aim of the study was to compare renal histologic features and parameters of renal function in diabetic cats against a control population matched for age, gender, breed, and body weight. Thirty-two diabetic and 20 control cats were included. Kidney sections from paraffin-embedded kidney samples were stained and examined with optical microscopy to identify glomerular, tubulointerstitial, and vascular lesions and to assess their frequency and severity. Serum creatinine and urea concentrations were also compared. Glomerular lesions were observed in 29 cats overall, with mesangial matrix increase being more common (19 cats). Tubulointerstitial lesions were observed in 42 cats, including lymphocytic infiltration (29), fibrosis (22), or tubular necrosis (21). Vascular lesions were observed in 5 cases. The frequency and severity of histologic lesions did not differ between diabetic and control cats; however, among diabetics, those that survived longer after diagnosis had more glomerular and vascular lesions. Serum creatinine and urea concentrations were similar between groups; in diabetic cats median creatinine was 109 μmol/l (range, 51-1200) and urea was 12 mmol/l (range, 4-63), and in controls creatinine was 126 μmol/l (range, 50-875) and urea 11 mmol/l (range, 3-80). The results suggest that DM in cats does not lead to microscopically detectable kidney lesions or clinically relevant renal dysfunction. The authors hypothesize that the short life expectancy of diabetic cats may be the main reason for the difference from human diabetics.

  11. Feline Epitheliotropic Mastocytic Conjunctivitis in 15 Cats.

    PubMed

    Beckwith-Cohen, B; Dubielzig, R R; Maggs, D J; Teixeira, L B C

    2017-01-01

    Mast cell infiltration occurs in malignant, inflammatory (eg, allergic, infectious), and idiopathic disease processes in humans and animals. Here, we describe the clinical and histological features of a unique proliferative conjunctivitis occurring in 15 cats. Ocular specimens were examined histologically, and polymerase chain reaction (PCR) for feline herpesvirus 1 (FHV-1) was performed on ocular tissues obtained from 10 cats. Cats had a median age of 8 years (range: 7 months-17.5 years). The known median duration of ocular lesions prior to biopsy was 4 months (range: 1 week-3 years). Ocular disease was unilateral in 12 cats, and 9 cats had coexisting corneal disease. Clinically and histologically, proliferative or nodular conjunctival lesions were noted in 13 cats. The nictitating membrane was affected in 10 cats. Histologically, lesions were characterized by mixed inflammatory infiltrates with an abundance of Giemsa-positive and toluidine blue-positive intraepithelial and subepithelial mast cells, marked edema, and papillary epithelial hyperplasia. Feline herpesvirus 1 was demonstrated by PCR in 1 of 10 cats tested. Follow-up information was available for 14 cats: 8 had no recurrence during a median follow-up period of 17.5 months (range: 4.5-30 months), 2 underwent orbital exenteration, 3 had recurrence that was medically managed, and 1 cat had diffuse conjunctivitis at the time of biopsy and recurrence was deemed irrelevant. Various ocular medications were administered before and after surgical biopsy. This condition was designated as feline epitheliotropic mastocytic conjunctivitis, with intraepithelial mast cells being an essential feature and papillary epithelial proliferation being characteristic but not diagnostic alone. The condition appears to be uncommon and benign. Although the cause is unknown, an allergic component is possible.

  12. Intermittent Turbulence in the Very Stable Ekman Layer

    SciTech Connect

    Barnard, James C

    2001-01-01

    This study describes a Direct Numerical Simulation (DNS) of a very stable Ekman layer in which a constant downward heat flux is applied at the lower boundary, thus cooling the fluid above. Numerical experiments were performed in which the strength of the imposed heat flux was varied. For downward heat fluxes above a certain critical value the turbulence becomes intermittent and, as the heat flux increases beyond this value, the flow tends to relaminarize because of the very strong ambient stratification. We adopt Mahrt?s (1999) definition of the very stable boundary layer as a boundary layer in which intermittent, rather than continuous turbulence, is observed. Numerical experiments were used to test various hypothesis of where in ?stability parameter space? the very stable boundary layer is found. These experiments support the findings of Howell and Sun (1999) that the boundary layer will exhibit intermittency and therefore be categorized as ?very stable?, when the stability parameter, z/L, exceeds unity. Another marker for the very stable boundary layer, Derbyshire?s (1990) maximum heat flux criterion, was also examined. Using a case study drawn from the simulations where turbulence intermittency was observed, the mechanism that causes the intermittence was investigated. It was found that patchy turbulence originates from a vigorous inflectional, Ekman-like instability -- a roll cell -- that lifts colder air over warmer air. The resulting convective instability causes an intense burst of turbulence. This turbulence is short-lived because the lifting motion of the roll cell, as well as the roll cell itself, is partially destroyed after the patchy turbulence is generated. Examples of intermittent turbulence obtained from the simulations appear to be consistent with observations of intermittency even though the Reynolds number of the DNS is relatively low (400).

  13. Intermittent turbulence in the very stable Ekman layer

    NASA Astrophysics Data System (ADS)

    Barnard, James Coles

    This study describes a Direct Numerical Simulation (DNS) of a very stable Ekman layer in which a constant downward heat flux is applied at the lower boundary, thus cooling the fluid above. Numerical experiments were performed in which the strength of the imposed heat flux was varied. For downward heat fluxes above a certain critical value the turbulence becomes intermittent and, as the heat flux increases beyond this value, the flow tends to relaminarize because of the very strong ambient stratification. We adopt Mahrt's (1999) definition of the very stable boundary layer as a boundary layer in which intermittent, rather than continuous turbulence, is observed. Numerical experiments were used to test various hypothesis of where in "stability parameter space" the very stable boundary layer is found. These experiments support the findings of Howell and Sun (1999) that the boundary layer will exhibit intermittency and therefore be categorized as "very stable", when the stability parameter, z/ Λ, exceeds unity. Another marker for the very stable boundary layer, Derbyshire's (1990) maximum heat flux criterion, was also examined. Using a case study drawn from the simulations where turbulence intermittency was observed, the mechanism that causes the intermittence was investigated. It was found that patchy turbulence originates from a vigorous inflectional, Ekman-like instability---a roll cell---that lifts colder air over warmer air. The resulting convective instability causes an intense burst of turbulence. This turbulence is short-lived because the lifting motion of the roll cell, as well as the roll cell itself, is partially destroyed after the patchy turbulence is generated. Examples of intermittent turbulence obtained from the simulations appear to be consistent with observations of intermittency even though the Reynolds number of the DNS is relatively low (400).

  14. Turbulent black holes.

    PubMed

    Yang, Huan; Zimmerman, Aaron; Lehner, Luis

    2015-02-27

    We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids.

  15. Bacterial turbulence in motion

    NASA Astrophysics Data System (ADS)

    Rusconi, Roberto; Smriga, Steven; Stocker, Roman; Secchi, Eleonora; Buzzaccaro, Stefano; Piazza, Roberto

    2014-11-01

    Dense suspensions of motile bacteria exhibit collective dynamics akin to those observed in classic, high Reynolds number turbulence, yet this analogy has remained largely qualitative. Here we present experiments in which a dense suspension of Bacillus subtilis bacteria was flown through narrow microchannels and the velocity statistics of the flowing suspension were accurately quantified with a recently developed velocimetry technique. This revealed a robust intermittency phenomenon, whereby the average velocity profile of the flowing suspension oscillated between a plug-like flow and a parabolic flow. This intermittency is a hallmark of classic turbulence and was associated with the presence of collective structures in the suspension. Furthermore, quantification of the Reynolds stress profile revealed a direct link between the turbulent nature of the suspension and its anomalous viscosity.

  16. LDV measurements of turbulent baroclinic boundary layers

    SciTech Connect

    Neuwald, P.; Reichenbach, H.; Kuhl, A.L.

    1993-07-01

    Described here are shock tube experiments of nonsteady, turbulent boundary layers with large density variations. A dense-gas layer was created by injecting Freon through the porous floor of the shock tube. As the shock front propagated along the layer, vorticity was created at the air-Freon interface by an inviscid, baroclinic mechanism. Shadow-schlieren photography was used to visualize the turbulent mixing in this baroclinic boundary layer. Laser-Doppler-Velocimetry (LDV) was used to measure the streamwise velocity histories at 14 heights. After transition, the boundary layer profiles may be approximated by a power-law function u {approximately} u{sup {alpha}} where {alpha} {approx_equal} 3/8. This value lies between the clean flat plate value ({alpha} = 1/7) and the dusty boundary layer value ({alpha} {approx_equal} 0.7), and is controlled by the gas density near the wall.

  17. Fractional Order Modeling of Atmospheric Turbulence - A More Accurate Modeling Methodology for Aero Vehicles

    NASA Technical Reports Server (NTRS)

    Kopasakis, George

    2014-01-01

    The presentation covers a recently developed methodology to model atmospheric turbulence as disturbances for aero vehicle gust loads and for controls development like flutter and inlet shock position. The approach models atmospheric turbulence in their natural fractional order form, which provides for more accuracy compared to traditional methods like the Dryden model, especially for high speed vehicle. The presentation provides a historical background on atmospheric turbulence modeling and the approaches utilized for air vehicles. This is followed by the motivation and the methodology utilized to develop the atmospheric turbulence fractional order modeling approach. Some examples covering the application of this method are also provided, followed by concluding remarks.

  18. Shock following a cat scratch.

    PubMed

    Yamamoto, Umpei; Kunita, Mutsumi; Mohri, Masahiro

    2013-01-11

    A 49-year-old man with fever, pain in both legs, purpuras and cyanosis was admitted to hospital. He was a heavy drinker, but did not have diabetes or other immunosuppressive disease. On admission, he was in shock, with haematological findings suggestive of disseminated intravascular coagulation, and liver and kidney failure. The presence of a scratch wound on his face caused by a cat, and linear, Gram-negative rods phagocytosed by polynuclear leucocytes on peripheral blood smear suggested Capnocytophaga canimorsus infection. On day 1, antibiotics (ampicillin/sulbactam) and catecholamines were initiated. The patient required haemodialysis three times per week for 3 weeks. His toes became necrotic but improved and amputation was not necessary. On day 52, he was discharged from hospital with only mild sensory impairment of the legs.

  19. CAT — EDRN Public Portal

    Cancer.gov

    The CAT gene product, catalase, occurs in the peroxisome of almost all respiring organismÃÆ'¢â‚¬â„¢s cells. Catalase is a heme enzyme that converts the reactive oxygen species hydrogen peroxide to water and oxygen, diminishing the toxic effects of hydrogen peroxide on the cell. Catalase promotes growth of cells including T-cells, B-cells, myeloid leukemia cells, melanoma cells, mastocytoma cells and normal and transformed fibroblast cells. Polymorphisms in this gene have been associated with decreases in catalase activity but, to date, acatalasemia is the only disease known to be caused by this gene.

  20. Interspecies transmission of feline immunodeficiency virus from the domestic cat to the Tsushima cat (Felis bengalensis euptilura) in the wild.

    PubMed

    Nishimura, Y; Goto, Y; Yoneda, K; Endo, Y; Mizuno, T; Hamachi, M; Maruyama, H; Kinoshita, H; Koga, S; Komori, M; Fushuku, S; Ushinohama, K; Akuzawa, M; Watari, T; Hasegawa, A; Tsujimoto, H

    1999-09-01

    Feline immunodeficiency virus (FIV) was isolated from a wild-caught Tsushima cat (Felis bengalensis euptilura), an endangered Japanese nondomestic subspecies of leopard cat (F. bengalensis). Phylogenetic analysis of the env gene sequences indicated that the FIV from the Tsushima cat belonged to a cluster of subtype D FIVs from domestic cats. FIVs from both the Tsushima cat and the domestic cat showed similar levels of replication and cytopathicity in lymphoid cell lines derived from these two species. The results indicated the occurrence of interspecies transmission of FIV from the domestic cat to the Tsushima cat in the wild.

  1. Laboratory Measurements of Turbulence Under Shoaling Waves

    NASA Astrophysics Data System (ADS)

    Kikuchi, M.; Veron, F.

    2003-12-01

    Understanding the sediment transport in surf and swash zone is essential for numerous coastal projects and applications. Many time-dependent models parameterize the sediment transport. While some can be quite successful in predicting the evolution of the bed shape, our understanding of the sediment suspension mechanisms is still rather poor. When the waves approach the shore and break, the energy of the waves is lost to the generation of turbulence and currents, the entrainment of bubbles, and a fraction of the energy from breaking waves is transferred to suspend the sediment particles. A further investigation of the turbulence caused by breaking waves, resulting in the suspension of the sediment particles from the beach bed, is therefore necessary to improve our understanding of the suspension processes. We have used a Particle Image Velocimetry (PIV) technique to study the temporal and spatial structure of the turbulence in the bottom boundary layer. The experiments were performed in the large linear wave flume at the Air-Sea Interaction Laboratory at the University of Delaware. Continuous linear monochromatic deepwater waves were mechanically generated and sent to break naturally on an adjustable planner Plexiglas beach. The beach angle was adjusted to 1:2.6, 1:3.2, or 1:4.6 and a number of wave amplitudes were utilized for each of the beach angle. The PIV field of view was also arranged parallel to the beach bottom and in the vertical plane. The measurements were taken after reaching a quasi-steady state. Ensemble phase averages are used to obtain mean and turbulent fields. Time evolution is studied to investigate the formation and evolution of the turbulent structures and hairpin vortices within the bottom boundary layer. The results are discussed in the context of sediment transport.

  2. Joint Agency Turbulence Experiment.

    DTIC Science & Technology

    1985-01-21

    Time Series of Aircraft Longitudinal Gust Data For Penetration 1 on 1 July 1981 63 C5. Time Series of Turbulence Severity Estimates Derived From 400 m...spectral analysis of aircraft longitudinal gust data is shown in Figure B1. Figure B2 shows a modeled turbulence field. The model displays the expected...centered about Location C o %-. -. °,4 0- S E - oo -12 -4 - to 20 so O so s 7D -U. TIME (sec) Figure C4. Time Series of Aircraft Longitudinal Gust Data

  3. Electromagnetic strong plasma turbulence

    SciTech Connect

    Melatos, A.; Jenet, F. A.; Robinson, P. A.

    2007-02-15

    The first large-scale simulations of continuously driven, two-dimensional electromagnetic strong plasma turbulence are performed, for electron thermal speeds 0.01c{<=}v{<=}0.57c, by integrating the Zakharov equations for coupled Langmuir and transverse (T) waves near the plasma frequency. Turbulence scalings and wave number spectra are calculated, a transition is found from a mix of trapped and free T eigenstates for v{>=}0.1c to just free eigenstates for v{<=}0.1c, and wave energy densities are observed to undergo slow quasiperiodic oscillations.

  4. Turbulence in Reynolds' flashes

    NASA Astrophysics Data System (ADS)

    Cerbus, Rory; Liu, Chien-Chia; Gioia, Gustavo; Chakraborty, Pinaki

    2016-11-01

    Osborne Reynolds' seminal work from 1883 revealed that the transition from quiescent, laminar flow to a turbulent pipe filled with roiling eddies is mediated by localized flashes of fluctuations. Later work has unveiled many features of these flashes: they proliferate or fade away, maintain their shape or continually expand. The nature of the fluctuations in the flashes, however, has remained mysterious. Here, using measures traditionally attributed to high Reynolds number (Re) flows, we present experimental results on the fluctuations of the flashes. Our results suggest that the transition to turbulence is the low Re limit of the high Re, fully developed flow. Okinawa Institute of Science and Technology.

  5. Turbulent jet mixing in a supersonic stream

    NASA Technical Reports Server (NTRS)

    Swanson, R. C.; Schetz, J. A.

    1971-01-01

    An experimental study of turbulent, subsonic, coaxial jet mixing of air in a supersonic air stream is presented. Data taken at five axial stations downstream of the exit of the jet supply tube, which was suspended through the nozzle throat of a supersonic wind tunnel, are given in the form of total pressure, Mach number, and velocity distributions. An investigation of the effect of swirl as a mixing aid was conducted. Swirl, produced by tangential injection of 50% of the total air mass flow leaving the jet supply tube, was examined through Schlieren photographs and total pressure surveys. From a comparison of nonswirl and swirl data, it is concluded that the swirl has no discernible effect on the mixing.

  6. Experimental Investigation of Active Feedback Control of Turbulent Transport in a Magnetized Plasma

    SciTech Connect

    Gilmore, Mark Allen

    2013-07-07

    A new and unique basic plasma science laboratory device - the HelCat device (HELicon-CAThode) - has been constructed and is operating at the University of New Mexico. HelCat is a 4 m long, 0.5 m diameter device, with magnetic field up to 2.2 kG, that has two independent plasmas sources - an RF helicon source, and a thermionic cathode. These two sources, which can operate independently or simultaneously, are capable of producing plasmas with a wide range of parameters and turbulence characteristics, well suited to a variety of basic plasma physics experiments. An extensive set of plasma diagnostics is also operating. Experiments investigating the active feedback control of turbulent transport of particles and heat via electrode biasing to affect plasma ExB flows are underway, and ongoing.

  7. Environmental Aspects of Domestic Cat Care and Management: Implications for Cat Welfare

    PubMed Central

    Stella, Judith L.

    2016-01-01

    Domestic cats (Felis silvestris catus) are the most commonly kept companion animals in the US with large populations of owned (86 million), free-roaming (70 million), research (13,000), and shelter (2-3 million) cats. Vast numbers of cats are maintained in homes and other facilities each year and are reliant on humans for all of their care. Understanding cat behavior and providing the highest quality environments possible, including positive human-cat interactions, based on research could help improve the outcomes of biomedical research, shelter adoptions, and veterinary care, as well as overall cat welfare. Often, however, cats' needs are inadequately met in homes and some aspects may also not be well met in research colonies and shelters, despite the fact that similar problems are likely to be encountered in all of these environments. This paper provides a brief overview of common welfare challenges associated with indoor housing of domestic cats. Essential considerations for cage confinement are reviewed, along with implications of poor cat coping, such as weakening of the human-animal bond and relinquishment to shelters. The important role that environmental management plays in cat behavior and welfare outcomes is explored along with the need for additional research in key areas. PMID:27774506

  8. Reduction of feral cat (Felis catus Linnaeus 1758) colony size following hysterectomy of adult female cats.

    PubMed

    Mendes-de-Almeida, Flavya; Remy, Gabriella L; Gershony, Liza C; Rodrigues, Daniela P; Chame, Marcia; Labarthe, Norma V

    2011-06-01

    The size of urban cat colonies is limited only by the availability of food and shelter; therefore, their population growth challenges all known population control programs. To test a new population control method, a free-roaming feral cat colony at the Zoological Park in the city of Rio de Janeiro was studied, beginning in 2001. The novel method consisted of performing a hysterectomy on all captured female cats over 6 months of age. To estimate the size of the colony and compare population from year to year, a method of capture-mark-release-recapture was used. The aim was to capture as many individuals as possible, including cats of all ages and gender to estimate numbers of cats in all population categories. Results indicated that the feral cat population remained constant from 2001 to 2004. From 2004 to 2008, the hysterectomy program and population estimates were performed every other year (2006 and 2008). The population was estimated to be 40 cats in 2004, 26 in 2006, and 17 cats in 2008. Although pathogens tend to infect more individuals as the population grows older and maintains natural behavior, these results show that free-roaming feral cat colonies could have their population controlled by a biannual program that focuses on hysterectomy of sexually active female cats.

  9. Critical issues encountered in experiments and measurements involving optical turbulence

    NASA Astrophysics Data System (ADS)

    Eaton, Frank D.

    2007-02-01

    The successful design and operation of high energy laser (HEL) and laser communication systems require a comprehensive and thorough knowledge of the real turbulent atmosphere coupled with high-fidelity realistic laser beam propagation models. To date, modeling and simulation of laser beam propagation through atmospheric turbulence have relied upon a traditional theoretical basis that assumes the existence of homogeneous, isotropic, stationary, and Kolmogorov turbulence. The real impact of the refractive index structure parameter ( C2 n ) on laser beam propagation including effects of non-classical turbulence as well as inner (l °) and outer scale (L °) effects will be examined. Observations clearly show turbulence is often layered and is produced by wave activity and episodic events such as Kelvin-Helmholtz instabilities. Other critical turbulence issues involve the relationship between mechanical and optical turbulence and the effect of path variability of turbulence and inner scale on optical turbulence parameters over long paths. These issues will be examined from data obtained from five systems: a) a new measurement platform using a free-flying balloon that lifts a ring with a boom upon which are mounted several fine wire (1-μm diameter) sensors to measure high-speed temperature and velocity fluctuations, b) a new system using a kite/tethered blimp platform that obtains both profile and measurements at a fixed altitude over time, c) a 50 MHz radar at Vandenberg Air Force Base that senses at high temporal and spatial resolution to 20 km ASL, d) an instrumented aircraft system, and e) a suite of optical systems. The first four systems all provide estimates of C2 n , the eddy dissipation rate (\\Vegr), l ° and L °. Methods of calibration and problems of interpreting results from the measurement systems are discussed.

  10. The Chediak-Higashi syndrome of cats.

    PubMed

    Kramer, J W; Davis, W C; Prieur, D J

    1977-05-01

    Initial clinical, genetic, cytochemical and ultrastructural studies have characterized the Chediak-Higashi syndrome in cats. Three cats with Chediak-Higashi syndrome were found in a single line of 27 Persian cats, and three additional affected cats were produced from two prospective breedings of the original line. The disorder was characterized genetically as an autosomal recessive condition. All cats in the line with the combination of yellow eye color and "blue smoke" hair color exhibited the disorder. Four of the five cats examined had bilateral nuclear cataracts as early in life as 3 months of age. No increased susceptibility to infectious disease was observed. A bleeding tendency was noted. Abnormally large eosinophilic, sudanophilic, peroxidase-containing granules were observed in the neutrophils of the granulocytic series of blood and bone marrow by electron and light microscopy. Granules of eosinophils and basophils were also enlarged. Light microscopic studies of hair and skin revealed enlarged melanin granules. These manifestations were similar to those in man, mink, cattle, mice, and the killer whale with Chediak-Higashi syndrome. Cats are the sixth species in which this genetic disease has been reported.

  11. Urate excretion by the cat kidney.

    PubMed

    Kim, Y K; Jung, D K; Jung, J S; Lee, S H

    1992-08-01

    1. The renal handling of urate by the cat kidney was investigated during continuous infusion of urate. 2. Fractional urate excretion (FE(UA)) in cats was 0.57 +/- 0.04, indicating net reabsorption of urate. In contrast, FE(UA) in rabbits was 1.76 +/- 0.08, reflecting net secretion of urate. 3. Fractional PAH excretion (FE(PAH)) was 3.94 +/- 0.26 in cats and 4.12 +/- 0.76 in rabbits, showing net secretion in both species. 4. FE(UA) in cats was dependent on urine flow, but was independent of plasma urate concentration. 5. The urate excretion in cats was enhanced by probenecid, but was insensitive to PAH and PZA. 6. The PAH excretion in cats was reduced by probenecid, but was unaltered by urate and PZA. 7. These results indicate that urate is handled in the cat kidney by a unique transport system which is distinct from that for organic anions.

  12. Hookworms of feral cats in Florida.

    PubMed

    Anderson, Tara Creel; Foster, Garry W; Forrester, Donald J

    2003-07-10

    Thirty feral cats (Felis catus) from Alachua county (northern Florida) and 30 from Palm Beach county (southern Florida) were examined for hookworms. Two species, Ancylostoma tubaeforme and Ancylostoma braziliense, were identified. Forty-five cats (75%) were infected with A. tubaeforme, with a mean intensity of 48 hookworms per cat. Twenty cats (33%) were infected with A. braziliense, with a mean intensity of 28 worms per cat. The prevalence of A. tubaeforme was greater than that of A. braziliense in Alachua (P=0.002) and Palm Beach (P=0.004) counties. The intensity of A. tubaeforme infections was higher in Palm Beach county than Alachua county (P=0.013). The intensities of A. tubaeforme and A. braziliense were positively correlated (increased together) in Palm Beach county (P=0.011). These hookworms have also been identified in bobcats (Felis rufus), gray foxes (Urocyon cinereoargenteus), and red foxes (Vulpes vulpes) in Florida. The prevalence of A. tubaeforme was significantly greater in feral cats than those reported in bobcats (P<0.001). The prevalence of A. braziliense was significantly greater in feral cats than in those reported in gray foxes (P=0.008). The hookworm that infects Florida panthers and bobcats, A. pluridentatum, was not found.

  13. Sources and dynamics of turbulence in the upper troposphere and lower stratosphere: A review

    NASA Astrophysics Data System (ADS)

    Sharman, R. D.; Trier, S. B.; Lane, T. P.; Doyle, J. D.

    2012-06-01

    Turbulence is a well-known hazard to aviation that is responsible for numerous injuries each year, with occasional fatalities, and is the underlying cause of many people's fear of air travel. Not only are turbulence encounters a safety issue, they also result in millions of dollars of operational costs to airlines, leading to increased costs passed on to the consumer. For these reasons, pilots, dispatchers, and air traffic controllers attempt to avoid turbulence wherever possible. Accurate forecasting of aviation-scale turbulence has been hampered in part by a lack of understanding of the underlying dynamical processes. However, more precise observations of turbulence encounters together with recent research into turbulence generation processes is helping to elucidate the detailed dynamical processes involved and is laying the foundation for improved turbulence forecasting and avoidance. In this paper we briefly review some of the more important recent observational, theoretical, and modeling results related to turbulence at cruise altitudes for commercial aircraft (i.e., the upper troposphere and lower stratosphere), and their implications for aviation turbulence forecasting.

  14. Exocrine Pancreas in Cats With Diabetes Mellitus.

    PubMed

    Zini, E; Ferro, S; Lunardi, F; Zanetti, R; Heller, R S; Coppola, L M; Guscetti, F; Osto, M; Lutz, T A; Cavicchioli, L; Reusch, C E

    2016-01-01

    Pancreatitis has been described in cats with diabetes mellitus, although the number of studies currently available is very limited. In addition, ketoacidosis has been hypothesized to be associated with pancreatitis in diabetic cats. The aims of the present study were to investigate whether diabetic cats have pancreatitis and to determine if pancreatitis is more frequent with ketoacidosis. Samples of pancreas were collected postmortem from 37 diabetic cats, including 15 with ketoacidosis, and 20 control cats matched for age, sex, breed, and body weight. Sections were stained with hematoxylin and eosin, double-labeled for insulin/CD3, insulin/CD20, insulin/myeloperoxidase, insulin/PCNA, and glucagon/Ki67, and single-labeled for Iba1. A previously proposed semiquantitative score was used to characterize pancreatitis, along with counts of inflammatory cells. Scores of pancreatitis and the number of neutrophils, macrophages, and lymphocytes in the exocrine pancreas did not differ between diabetic and control cats or between diabetic cats with and without ketoacidosis. Of note, PCNA-positive acinar cells were increased (P = .002) in diabetic cats, particularly near islets (P < .001). Ki67-positive acinar cells were increased only near islets (P = .038). Ketoacidosis was not linked to proliferation. The results suggest that histopathologic evidence of pancreatitis may not be more frequent in diabetic cats and that ketoacidosis may not be associated with it at the time of death. Augmented PCNA-positive acinar cells might indicate increased proliferation due to chronic pancreatitis. The reason behind the prevalent proliferation of acinar cells surrounding pancreatic islets deserves further investigation.

  15. Turbulence characteristics inside a turbulent spot in plane Poiseuille flow

    NASA Technical Reports Server (NTRS)

    Henningson, Dan S.; Kim, John

    1989-01-01

    Turbulence characteristics inside a turbulent spot in plane Poiseuille flow are investigated by analyzing a database obtained from a direct simulation. The spot area is divided into two distinct regions - a turbulent area and a wave area. It is found that the flow structures inside the turbulent area have strong resemblance to those found in the fully-developed turbulent channel flow. A suitably defined mean and rms fluctuations as well as the internal shear-layer structures are found to be similar to the turbulent counterpart. In the wave area the inflexional mean spanwise profiles cause a rapid growth of oblique waves, which break down to turbulence. The rms fluctuations and Reynolds stress are found to be higher in that area, and the shear-layer structures are similar to those observed in the secondary instability of two-dimensional Tollmien-Schlichting waves.

  16. 14 CFR 25.1517 - Rough air speed, VRA.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Rough air speed, VRA. 25.1517 Section 25... Limitations § 25.1517 Rough air speed, VRA. A rough air speed, VRA, for use as the recommended turbulence... rough air encounters will not cause the overspeed warning to operate too frequently. In the absence of...

  17. Cat scratch disease from a domestic dog.

    PubMed

    Chen, Tun-Chieh; Lin, Wei-Ru; Lu, Po-Liang; Lin, Chun-Yu; Chen, Yen-Hsu

    2007-02-01

    Cat scratch disease (CSD), caused by Bartonella henselae, is a zoonosis and characterized by self-limited lymphadenopathy. It is transmitted commonly by scratch or bite from cats or kitten. We report an unusual case of CSD caused by a domestic dog scratch that we believe is the first report in Taiwan. A 23-year-old healthy woman developed cervical lymphadenopathy, mild fever, headache, and malaise 3 days after dog scratch. Her symptoms improved after azithromycin treatment. Serology proved B. henselae infection. The owners of a domestic dog might be at risk of "cat" scratch disease.

  18. Cytogenetic investigation of cat-eye syndrome.

    PubMed

    Walknowska, J; Peakman, D; Weleber, R G

    1977-10-01

    Using multiple chromosomal banding techniques, we studied a child with typical cat-eye syndrome and ocular retraction syndrome. Although the mother was was chromosomally normal, other maternal relatives showed features of the cat-eye syndrome, suggesting the basic abnormality is heritable. The abnormal chromosome in our case was most likely the product of reciprocal translocation where short arm plus centromeric chromatin from two separate acrocentric chromosomes fused together. The chromosomes involved were probably No. 22 and either Nos. 13 or 14. The basic underlying defect in cat-eye syndrome may be a heritable fragile site or some other predisposition leading to complex chromosomal interchange.

  19. Aspergillus species cystitis in a cat.

    PubMed

    Adamama-Moraitou, K K; Paitaki, C G; Rallis, T S; Tontis, D

    2001-03-01

    A Persian male cat with a history of lower urinary tract disease was presented because of polydipsia, polyuria, constipation and nasal discharge. Ten weeks before admission, the cat had been treated for lower urinary tract disease by catheterisation and flushing of the bladder. The animal was thin, dehydrated, anaemic and azotaemic. Urine culture revealed Aspergillus species cystitis. Antibodies against Aspergillus nidulans were identified in serum. Fluconazole was administered orally (7.5 mg/kg, q 12 h) for 10 consecutive weeks. The azotaemia was resolved, the kidney concentrating ability was recovered and the cat has remained healthy without similar problems.

  20. Turbulent Flame Propagation Characteristics of High Hydrogen Content Fuels

    SciTech Connect

    Seitzman, Jerry; Lieuwen, Timothy

    2014-09-30

    This final report describes the results of an effort to better understand turbulent flame propagation, especially at conditions relevant to gas turbines employing fuels with syngas or hydrogen mixtures. Turbulent flame speeds were measured for a variety of hydrogen/carbon monoxide (H2/CO) and hydrogen/methane (H2/CH4) fuel mixtures with air as the oxidizer. The measurements include global consumption speeds (ST,GC) acquired in a turbulent jet flame at pressures of 1-10 atm and local displacement speeds (ST,LD) acquired in a low-swirl burner at atmospheric pressure. The results verify the importance of fuel composition in determining turbulent flame speeds. For example, different fuel-air mixtures having the same unstretched laminar flame speed (SL,0) but different fuel compositions resulted in significantly different ST,GC for the same turbulence levels (u'). This demonstrates the weakness of turbulent flame speed correlations based simply on u'/SL,0. The results were analyzed using a steady-steady leading points concept to explain the sensitivity of turbulent burning rates to fuel (and oxidizer) composition. Leading point theories suggest that the premixed turbulent flame speed is controlled by the flame front characteristics at the flame brush leading edge, or, in other words, by the flamelets that advance farthest into the unburned mixture (the so-called leading points). For negative Markstein length mixtures, this is assumed to be close to the maximum stretched laminar flame speed (SL,max) for the given fuel-oxidizer mixture. For the ST,GC measurements, the data at a given pressure were well-correlated with an SL,max scaling. However the variation with pressure was not captured, which may be due to non-quasi-steady effects that are not included in the current model. For the ST,LD data, the leading points model again faithfully captured the variation of turbulent flame speed over a wide range of fuel-compositions and turbulence intensities. These results provide

  1. Effect of de-correlating turbulence on the low frequency decay of jet-surface interaction noise in sub-sonic unheated air jets using a CFD-based approach

    NASA Astrophysics Data System (ADS)

    Afsar, M. Z.; Leib, S. J.; Bozak, R. F.

    2017-01-01

    In this paper we extend the Rapid-distortion theory (RDT)-based model derived by Goldstein, Afsar & Leib (J. Fluid Mech., vol. 736, pp. 532-569, 2013) for the sound generated by the interaction of a large-aspect-ratio rectangular jet with the trailing edge of a flat plate to include a more realistic upstream turbulence spectrum that possess a de-correlation (i.e. negative dip) in its space-time structure and use results from three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solutions to determine the mean flow, turbulent kinetic energy and turbulence length & time scales. Since the interaction noise dominates the low-frequency portion of the spectrum, we use an appropriate asymptotic approximation for the Rayleigh equation Green's function, which enters the analysis, based on a two-dimensional mean flow representation for the jet. We use the model to predict jet-surface interaction noise for a range of subsonic acoustic Mach number jets, nozzle aspect ratios, streamwise and transverse trailing-edge locations and compare them with experimental data. The RANS meanflow computations are also compared with flow data for selected cases to assess their validity. We find that finite de-correlation in the turbulence spectrum increases the low-frequency algebraic decay (the low-frequency "roll-off") of the acoustic spectrum with angular frequency to give a model that has a pure dipole frequency scaling. This gives better agreement with noise data compared to Goldstein et al. (2013) for Strouhal numbers less than the peak jet-surface interaction noise. For example, through sensitivity analysis we find that there is a difference of 10 dB at the lowest frequency for which data exists (relative to a model without de-correlation effects included) for the highest acoustic Mach number case. Secondly, our results for the planar flow theory provide a first estimate of the low-frequency amplification due to the jet-surface interaction for moderate aspect ratio nozzles when RANS

  2. Consideration of Turbulence Effects in One-Dimensional Laminar Flamelet Equations

    NASA Astrophysics Data System (ADS)

    Chan, Wai Lee; Ihme, Matthias

    2014-11-01

    The laminar flamelet formulation has been used as a fundamental building block for the construction of turbulent combustion closures. By assuming that turbulence only leads to a deformation and straining of the local flame structure, the turbulence/chemistry interaction is then considered through a presumed shape probability density function (PDF) approach. However, the consistency of this approach remains unclear in the context of large-eddy simulations (LES), and the objective of this study is to examine the representation of turbulent scalar fluxes and turbulence/chemistry coupling on the flame structure. To this end, a detailed numerical simulation of a turbulent counterflow diffusion flame is performed, and the simulation results are used to analyze the limitations of the classic laminar flamelet formulation and explore a possible alternative approach. Financial support through the Air Force Office of Scientific Research under Award No. FA9550-11-1-0031 is gratefully acknowledged.

  3. Flows, Turbulence, and Mixing

    NASA Astrophysics Data System (ADS)

    Lazarian, Alex

    2003-07-01

    HST and FUSE spectra of distant UV-bright sources reveal interstellar absorption lines of high stages of ionization {O VI, C IV, N V, Si IV} arising in many different astrophysical environments such as superbubbles, interstellar chimneys, high-velocity clouds, galaxy halos and cosmic filaments. Turbulence, always present in the magnetized ISM, must mix the hot { 10^6 K} gas with cooler gas within "turbulent mixing layers". Present theory, based on 1D steady-state flows, suggest the line ratios in these layers differ significantly from photoionized gas, radiative shocks, cooling zones, or conduction fronts. These models are use to infer mass and energy fluxes important to understanding the ISM. We propose to develop a suite of 3D time-dependent models that properly calculate turbulent mixing. We will produce synthetic UV absorption lines and optical emission lines directly relevant to HST observations that use GHRS, STIS, and eventually, COS. These models will allow us to explore the sensitivity of the spectral diagnostics to magnetic field strength, turbulence intensity, and relative velocity of the hot and cold gas. We will publish the resulting grid of spectral diagnostics and make them available through the Web.

  4. Chemically Reacting Turbulent Flow.

    DTIC Science & Technology

    1987-04-14

    two stages of gen I tubes equipped with P-47 phosphor screens The detector chosen for the camera was a Reticon RL128S* line detectoI- .,hich consists...the Stud’, of Turbulent Mixing," William M. Pitts, Nuclear Engineering Seminar of the Department of Chemical and Nuclear Engineering, University of

  5. Dissipation in unsteady turbulence

    NASA Astrophysics Data System (ADS)

    Bos, Wouter J. T.; Rubinstein, Robert

    2017-02-01

    Recent experiments and simulations have shown that unsteady turbulent flows display a universal behavior at short and intermediate times, different from classical scaling relations. The origin of these observations is explained using a nonequilibrium correction to Kolmogorov's energy spectrum, and the exact form of the observed universal scaling is derived.

  6. Multilevel turbulence simulations

    SciTech Connect

    Tziperman, E.

    1994-12-31

    The authors propose a novel method for the simulation of turbulent flows, that is motivated by and based on the Multigrid (MG) formalism. The method, called Multilevel Turbulence Simulations (MTS), is potentially more efficient and more accurate than LES. In many physical problems one is interested in the effects of the small scales on the larger ones, or in a typical realization of the flow, and not in the detailed time history of each small scale feature. MTS takes advantage of the fact that the detailed simulation of small scales is not needed at all times, in order to make the calculation significantly more efficient, while accurately accounting for the effects of the small scales on the larger scale of interest. In MTS, models of several resolutions are used to represent the turbulent flow. The model equations in each coarse level incorporate a closure term roughly corresponding to the tau correction in the MG formalism that accounts for the effects of the unresolvable scales on that grid. The finer resolution grids are used only a small portion of the simulation time in order to evaluate the closure terms for the coarser grids, while the coarse resolution grids are then used to accurately and efficiently calculate the evolution of the larger scales. The methods efficiency relative to direct simulations is of the order of the ratio of required integration time to the smallest eddies turnover time, potentially resulting in orders of magnitude improvement for a large class of turbulence problems.

  7. Spirituality in Turbulent Times.

    ERIC Educational Resources Information Center

    Wheatley, Margaret J.

    2002-01-01

    Discusses the importance of spiritual leadership in turbulent, uncertain times. Describes several spiritual principles--for example, life is cyclical; all life is interconnected. Offers six suggestions for personal health: Start day peacefully, learn to be mindful, slow things down, create own measures, expect surprise, practice gratefulness. (PKP)

  8. Heart rate turbulence.

    PubMed

    Cygankiewicz, Iwona

    2013-01-01

    Heart rate turbulence (HRT) is a baroreflex-mediated biphasic reaction of heart rate in response to premature ventricular beats. Heart rate turbulence is quantified by: turbulence onset (TO) reflecting the initial acceleration of heart rate following premature beat and turbulence slope (TS) describing subsequent deceleration of heart rate. Abnormal HRT identifies patients with autonomic dysfunction or impaired baroreflex sensitivity due to variety of disorders, but also may reflect changes in autonomic nervous system induced by different therapeutic modalities such as drugs, revascularization, or cardiac resynchronization therapy. More importantly, impaired HRT has been shown to identify patients at high risk of all-cause mortality and sudden death, particularly in postinfarction and congestive heart failure patients. It should be emphasized that abnormal HRT has a well-established role in stratification of postinfarction and heart failure patients with relatively preserved left ventricular ejection fraction. The ongoing clinical trials will document whether HRT can be used to guide implantation of cardioverter-defibrillators in this subset of patients, not covered yet by ICD guidelines. This review focuses on the current state-of-the-art knowledge regarding clinical significance of HRT in detection of autonomic dysfunction and regarding the prognostic significance of this parameter in predicting all-cause mortality and sudden death.

  9. The Theories of Turbulence

    NASA Technical Reports Server (NTRS)

    Bass, J; Agostini, L

    1955-01-01

    The theory of turbulence reached its full growth at the end of the 19th century as a result of the work by Boussinesq and Reynolds. It then underwent a long period of stagnation which ended under the impulse given to it by the development of wind tunnels caused by the needs of aviation. Numerous researchers, attempted to put Reynolds' elementary statistical theory into a more precise form. During the war, some isolated scientists - von Weizsacker and Heisenberg in Germany, Kolmogoroff in Russia, Onsager in the U.S.A. - started a program of research. By a system of assumptions which make it possible to approach the structure of turbulence in well-defined limiting conditions quantitatively, they obtained a certain number of laws on the correlations and the spectrum. Since the late reports have improved the mathematical language of turbulence, it was deemed advisable to start with a detailed account of the mathematical methods applicable to turbulence, inspired at first by the work of the French school, above all for the basic principles, then the work of the foreigners, above all for the theory of the spectrum.

  10. Workshop on Computational Turbulence Modeling

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This document contains presentations given at Workshop on Computational Turbulence Modeling held 15-16 Sep. 1993. The purpose of the meeting was to discuss the current status and future development of turbulence modeling in computational fluid dynamics for aerospace propulsion systems. Papers cover the following topics: turbulence modeling activities at the Center for Modeling of Turbulence and Transition (CMOTT); heat transfer and turbomachinery flow physics; aerothermochemistry and computational methods for space systems; computational fluid dynamics and the k-epsilon turbulence model; propulsion systems; and inlet, duct, and nozzle flow.

  11. Remarks on turbulent constitutive relations

    NASA Technical Reports Server (NTRS)

    Shih, Tsan-Hsing; Lumley, John L.

    1993-01-01

    The paper demonstrates that the concept of turbulent constitutive relations can be used to construct general models for various turbulent correlations. Some of the Generalized Cayley-Hamilton formulas for relating tensor products of higher extension to tensor products of lower extension are introduced. The combination of dimensional analysis and invariant theory can lead to 'turbulent constitutive relations' (or general turbulence models) for, in principle, any turbulent correlations. As examples, the constitutive relations for Reynolds stresses and scalar fluxes are derived. The results are consistent with ones from Renormalization Group (RNG) theory and two-scale Direct-Interaction Approximation (DIA) method, but with a more general form.

  12. Earliest "Domestic" Cats in China Identified as Leopard Cat (Prionailurus bengalensis).

    PubMed

    Vigne, Jean-Denis; Evin, Allowen; Cucchi, Thomas; Dai, Lingling; Yu, Chong; Hu, Songmei; Soulages, Nicolas; Wang, Weilin; Sun, Zhouyong; Gao, Jiangtao; Dobney, Keith; Yuan, Jing

    2016-01-01

    The ancestor of all modern domestic cats is the wildcat, Felis silvestris lybica, with archaeological evidence indicating it was domesticated as early as 10,000 years ago in South-West Asia. A recent study, however, claims that cat domestication also occurred in China some 5,000 years ago and involved the same wildcat ancestor (F. silvestris). The application of geometric morphometric analyses to ancient small felid bones from China dating between 5,500 to 4,900 BP, instead reveal these and other remains to be that of the leopard cat (Prionailurus bengalensis). These data clearly indicate that the origins of a human-cat 'domestic' relationship in Neolithic China began independently from South-West Asia and involved a different wild felid species altogether. The leopard cat's 'domestic' status, however, appears to have been short-lived--its apparent subsequent replacement shown by the fact that today all domestic cats in China are genetically related to F. silvestris.

  13. Turbulence Modeling Workshop

    NASA Technical Reports Server (NTRS)

    Rubinstein, R. (Editor); Rumsey, C. L. (Editor); Salas, M. D. (Editor); Thomas, J. L. (Editor); Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    Advances in turbulence modeling are needed in order to calculate high Reynolds number flows near the onset of separation and beyond. To this end, the participants in this workshop made the following recommendations. (1) A national/international database and standards for turbulence modeling assessment should be established. Existing experimental data sets should be reviewed and categorized. Advantage should be taken of other efforts already under-way, such as that of the European Research Community on Flow, Turbulence, and Combustion (ERCOFTAC) consortium. Carefully selected "unit" experiments will be needed, as well as advances in instrumentation, to fill the gaps in existing datasets. A high priority should be given to document existing turbulence model capabilities in a standard form, including numerical implementation issues such as grid quality and resolution. (2) NASA should support long-term research on Algebraic Stress Models and Reynolds Stress Models. The emphasis should be placed on improving the length-scale equation, since it is the least understood and is a key component of two-equation and higher models. Second priority should be given to the development of improved near-wall models. Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES) would provide valuable guidance in developing and validating new Reynolds-averaged Navier-Stokes (RANS) models. Although not the focus of this workshop, DNS, LES, and hybrid methods currently represent viable approaches for analysis on a limited basis. Therefore, although computer limitations require the use of RANS methods for realistic configurations at high Reynolds number in the foreseeable future, a balanced effort in turbulence modeling development, validation, and implementation should include these approaches as well.

  14. 9 CFR 113.39 - Cat safety tests.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Cat safety tests. 113.39 Section 113... Procedures § 113.39 Cat safety tests. The safety tests provided in this section shall be conducted when... recommended for use in cats. (a) The cat safety test provided in this paragraph shall be used when the...

  15. 9 CFR 113.39 - Cat safety tests.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Cat safety tests. 113.39 Section 113... Procedures § 113.39 Cat safety tests. The safety tests provided in this section shall be conducted when... recommended for use in cats. (a) The cat safety test provided in this paragraph shall be used when the...

  16. 9 CFR 113.39 - Cat safety tests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Cat safety tests. 113.39 Section 113... Procedures § 113.39 Cat safety tests. The safety tests provided in this section shall be conducted when... recommended for use in cats. (a) The cat safety test provided in this paragraph shall be used when the...

  17. 9 CFR 113.39 - Cat safety tests.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Cat safety tests. 113.39 Section 113... Procedures § 113.39 Cat safety tests. The safety tests provided in this section shall be conducted when... recommended for use in cats. (a) The cat safety test provided in this paragraph shall be used when the...

  18. 9 CFR 113.39 - Cat safety tests.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Cat safety tests. 113.39 Section 113... Procedures § 113.39 Cat safety tests. The safety tests provided in this section shall be conducted when... recommended for use in cats. (a) The cat safety test provided in this paragraph shall be used when the...

  19. Dynamics of Turbulence Suppression in a Helicon Plasma

    NASA Astrophysics Data System (ADS)

    Hayes, Tiffany; Gilmore, Mark

    2012-10-01

    Experiments are currently being conducted in the the Helicon-Cathode Device (HelCat) at the University of New Mexico. The goal is to the study in detail the transition from a turbulent to a non-turbulent state in the presence of flow shear. HelCat has intrinsic fluctuations that have been identified as drift-waves. Using simple electrode biasing, it has been found that these fluctuations can be completely suppressed. In some extreme cases, a different instability, possibly the Kelvin-Helmholtz instability, can be excited. Detailed studies are underway in order to understand the characteristics of each mode, and to elucidate the underlying physics that cause the change between an unstable plasma, and an instability-free plasma. Dynamics being observed include changes in flow profiles, both azimuthal and parallel, as well as changes in potential and temperature gradients. Further understanding is being sought using several computer codes developed at EPFL: a linear stability solver (LSS,footnotetextP. Ricci and B.N. Rogers (2009). Phys Plasmas 16, 062303. a one-dimensional PIC code/sheath solver, ODISEE,footnotetextJ. Loizu, P. Ricci, and C. Theiler (2011). Phys Rev E 83, 016406 and a global, 3D Braginski code, GBS.footnotetextRicci, Rogers (2009) A basic overview of results will be presented.

  20. Transmission of feline immunodeficiency virus (FIV) among cohabiting cats in two cat rescue shelters.

    PubMed

    Litster, Annette L

    2014-08-01

    Conflicting accounts have been published in the veterinary literature regarding transmission of feline immunodeficiency virus (FIV) between cohabiting cats in mixed households, and the mechanics of possible casual transmission, if it occurs, are poorly understood. Similarly, there are conflicting reports of vertical transmission of FIV. The aim of the present study was to document the FIV serological status of cats taken into two rescue shelters. At rescue shelter 1 (Rescue 1), cats cohabited in a multi-cat household of FIV-negative and naturally-infected, FIV-positive cats. A study was performed that combined a retrospective review of records of FIV serological status at intake (Test 1) and prospective FIV serological testing (Tests 2 and 3). Retrospective records were analyzed at rescue shelter 2 (Rescue 2), where FIV-positive queens with litters of nursing kittens were taken into the shelter, before being rehomed. FIV serology was performed on all kittens after weaning. Initial test results (Test 1) for 138 cohabiting cats from Rescue 1 showed that there were 130 FIV-negative cats and eight FIV-positive cats (six male neutered and two female spayed). A second test (Test 2), performed in 45 of the FIV-negative and five of the FIV-positive cats at median 28 months after Test 1 (range, 1 month to 8.8 years) showed that results were unchanged. Similarly, a third test (Test 3), performed in four of the original FeLV-negative cats and one remaining FIV-positive cat at median 38 months after Test 1 (range, 4 months to 4 years), also showed that results were unchanged. These results show a lack of evidence of FIV transmission, despite years of exposure to naturally-infected, FIV-positive cats in a mixed household. At Rescue 2, records were available from five FIV-positive queens with 19 kittens. All 19 kittens tested FIV-negative, suggesting that vertical transmission had not occurred.

  1. An Examination of Aviation Accidents Associated with Turbulence, Wind Shear and Thunderstorm

    NASA Technical Reports Server (NTRS)

    Evans, Joni K.

    2013-01-01

    The focal point of the study reported here was the definition and examination of turbulence, wind shear and thunderstorm in relation to aviation accidents. NASA project management desired this information regarding distinct subgroups of atmospheric hazards, in order to better focus their research portfolio. A seven category expansion of Kaplan's turbulence categories was developed, which included wake turbulence, mountain wave turbulence, clear air turbulence, cloud turbulence, convective turbulence, thunderstorm without mention of turbulence, and low altitude wind shear, microburst or turbulence (with no mention of thunderstorms).More than 800 accidents from flights based in the United States during 1987-2008 were selected from a National Transportation Safety Board (NTSB) database. Accidents were selected for inclusion in this study if turbulence, thunderstorm, wind shear or microburst was considered either a cause or a factor in the accident report, and each accident was assigned to only one hazard category. This report summarizes the differences between the categories in terms of factors such as flight operations category, aircraft engine type, the accident's geographic location and time of year, degree of injury to aircraft occupants, aircraft damage, age and certification of the pilot and the phase of flight at the time of the accident.

  2. Acute monocytic leukaemia in a cat.

    PubMed

    Nagashima, N; Kano, R; Hirai, A; Yamazaki, J; Inoue, C; Hisasue, M; Moore, P F; Hasegawa, A

    2005-09-17

    A three-year-old cat with lymphadenopathy, non-regenerative anaemia and marked leucocytosis (171.3 x 10(9) white blood cells/l) was diagnosed with monocytic leukaemia and treated with a combination of anticancer drugs. A number of mature and immature monocyte-like cells were detected in the peripheral blood and bone marrow; they proved to be monocytic cells by cytochemical examination and an analysis of their cell surface phenotype, indicating that the cat suffered from acute myeloid leukaemia, subclassified as monocytic leukaemia (M5). Treatment with cytarabine, doxorubicin, vincristine and prednisolone greatly reduced the number of blast cells in the cat's peripheral blood and bone marrow. The cat was in partial remission for 67 days and survived for 95 days after it was first examined.

  3. Arrhythmogenic right ventricular cardiomyopathy in two cats.

    PubMed

    Harvey, A M; Battersby, I A; Faena, M; Fews, D; Darke, P G G; Ferasin, L

    2005-03-01

    Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disease characterised by infiltration of the myocardium by adipose and fibrous tissue. The disease is an important cause of sudden death in humans, but has rarely been described in animals. This report describes ARVC in two cats with right-sided congestive heart failure. One cat had also experienced previous episodes of syncope. Standard six-lead and 24-hour (Holter) electrocardiogram recording revealed complete atrioventricular block and multiform ventricular ectopics in both cats, with the addition of ventricular tachycardia, ventricular bigeminy and R-on-T phenomenon in one of them. On echocardiography, the right ventricle and atrium were massively dilated and hypokinetic. The survival times of the cats were three days and 16 days following diagnosis. Histopathology in one case revealed fibro-fatty infiltration of the myocardium, predominantly affecting the right ventricular free wall.

  4. Peripheral pulmonary artery stenosis in three cats

    PubMed Central

    AOKI, Takuma; SUNAHARA, Hiroshi; SUGIMOTO, Keisuke; ITO, Tetsuro; KANAI, Eiichi; FUJII, Yoko

    2014-01-01

    Case 1 involved a 4-month-old intact male Somali cat in which peripheral pulmonary artery stenosis (PPS) was recognized after a cardiac murmur remained following patent ductus arteriosus ligation. Case 2, which involved a 1-year-old neutered male Norwegian Forest cat, and Case 3, which involved a 6-month-old intact female American Curl cat, were referred, because of cardiac murmurs. Grades III to IV/VI systolic heart murmurs were auscultated at the left heart base in all 3 cats. All cases showed bilateral pulmonary artery stenosis, although there were no associated clinical signs. In Cases 1 and 2, the pressure gradient through the stenosis decreased after treatment with atenolol. PMID:25650057

  5. SWMM-CAT User’s Guide

    EPA Science Inventory

    The Storm Water Management Model Climate Adjustment Tool (SWMM-CAT) is a simple to use software utility that allows future climate change projections to be incorporated into the Storm Water Management Model (SWMM).

  6. Cats of the Pharaohs: Genetic Comparison of Egyptian Cat Mummies to their Feline Contemporaries

    PubMed Central

    Kurushima, Jennifer D.; Ikram, Salima; Knudsen, Joan; Bleiberg, Edward; Grahn, Robert A.; Lyons, Leslie A.

    2012-01-01

    The ancient Egyptians mummified an abundance of cats during the Late Period (664 - 332 BC). The overlapping morphology and sizes of developing wildcats and domestic cats confounds the identity of mummified cat species. Genetic analyses should support mummy identification and was conducted on two long bones and a mandible of three cats that were mummified by the ancient Egyptians. The mummy DNA was extracted in a dedicated ancient DNA laboratory at the University of California – Davis, then directly sequencing between 246 and 402 bp of the mtDNA control region from each bone. When compared to a dataset of wildcats (Felis silvestris silvestris, F. s. tristrami, and F. chaus) as well as a previously published worldwide dataset of modern domestic cat samples, including Egypt, the DNA evidence suggests the three mummies represent common contemporary domestic cat mitotypes prevalent in modern Egypt and the Middle East. Divergence estimates date the origin of the mummies’ mitotypes to between two and 7.5 thousand years prior to their mummification, likely prior to or during Egyptian Predyanstic and Early Dynastic Periods. These data are the first genetic evidence supporting that the ancient Egyptians used domesticated cats, F. s. catus, for votive mummies, and likely implies cats were domesticated prior to extensive mummification of cats. PMID:22923880

  7. Severe Turbulence and Maneuvering from Airline Flight Records

    NASA Technical Reports Server (NTRS)

    Wingrove, Rodney C.; Bach, R. E., Jr.

    1994-01-01

    Digital flight records from reported clear-air turbulence incidents are used to determine winds and turbulence, to determine maneuver g loads, and to analyze control problems. Many cases of severe turbulence are found downwind of mountains and thunderstorms where sharp, sudden jolts are associated with vortices in atmospheric waves. Other cases of severe turbulence are round in strong updrafts above thunderstorm buildups that may be undetected by onboard weather radar. An important finding is that there are large maneuvering loads in over half of the reported clear-air turbulence incidents. Maneuvering loads are determined through an analysis of the short-term variations in elevator deflection and aircraft pitch angle. For altitude control in mountain waves the results indicate that small pitch angle changes with proper timing are sufficient to counter variations in vertical wind. For airspeed control in strong mountain waves, however, there is neither the available thrust nor the quickness in engine response necessary to counter the large variations in winds.

  8. Satellite sensing of submerged fossil turbulence and zombie turbulence

    NASA Astrophysics Data System (ADS)

    Gibson, Carl H.

    2004-11-01

    Surface brightness anomalies from a submerged municipal wastewater outfall trapped by buoyancy in an area 0.1 km^2 are surprisingly detected from space satellites in areas > 200 km^2. How is this possible? Microstructure measurements near the outfall diffuser reveal enhanced turbulence and temperature dissipation rates above the 50 m trapping depth. Near-vertical radiation of internal waves by fossil and zombie turbulence microstructure patches produce wind ripple smoothing with 30-50 m internal wave patterns in surface Fourier brightness anomalies near the outfall. Detections at 10-14 km distances are at 100-220 m bottom boundary layer (BBL) fossil turbulence scales. Advected outfall fossils form zombie turbulence patches in internal wave patterns as they extract energy, vorticity, turbulence and ambient vertical internal wavelength information as their density gradients are tilted by the waves. As the zombies fossilize, patterned energy radiates near-vertically to produce the detected Fourier anomalies. Zombie turbulence patches beam extracted energy in a preferred direction with a special frequency, like energized metastable molecules in a chemical maser. Thus, kilowatts to produce the submerged field of advected fossil outfall turbulence patches are amplified by beamed zombie turbulence maser action (BZTMA) into megawatts of turbulence dissipation to affect sea surface brightness on wide surface areas using gigawatts of BBL fossil turbulence wave energy available.

  9. Second order Horner's syndrome in a cat.

    PubMed

    De Risio, Luisa; Fraser McConnell, James

    2009-08-01

    This case report describes the clinical and magnetic resonance imaging (MRI) findings of a 3.5-year-old, male neutered, domestic shorthair cat with second order Horner's syndrome as the only clinical abnormality. The neuroanatomical pathway of the sympathetic innervation to the eye, differential diagnoses for Horner's syndrome in cats, and the interpretation of pharmacological testing are reviewed. The unusual MRI findings and the value of fat-suppressed MRI sequences are discussed.

  10. [Spectacles for dogs and cats (author's transl)].

    PubMed

    Stades, F C

    1978-08-01

    Indications for using spectacles in dogs and cats are reviewed. These indications are classified into the following categories: (1) correction of visual acuity, (2) protection against external irritants such as ultraviolet rays and wind, (3) prevention of self-mutilation and (4) psychological reasons. The only justifiable indications for the use of spectacles or sun-glasses in dogs or cats consist in the treatment or prevention of some ophthalmic disorders.

  11. Version 2 Goddard Satellite-Based Surface Turbulent Fluxes (GSSTF2)

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.; Shie, Chung-Lin; Starr, David O'C. (Technical Monitor)

    2002-01-01

    Information on the turbulent fluxes of momentum, moisture, and heat at the air-sea interface is essential in improving model simulations of climate variations and in climate studies. We have derived a 13.5-year (July 1987-December 2000) dataset of daily surface turbulent fluxes over global oceans from the Special Sensor Mcrowave/Imager (SSM/I) radiance measurements. This dataset, version 2 Goddard Satellite-based Surface Turbulent Fluxes (GSSTF2), has a spatial resolution of 1 degree x 1 degree latitude-longitude and a temporal resolution of 1 day. Turbulent fluxes are derived from the SSM/I surface winds and surface air humidity, as well as the 2-m air and sea surface temperatures (SST) of the NCEP/NCAR reanalysis, using a bulk aerodynamic algorithm based on the surface layer similarity theory.

  12. Detailed thermodynamic analyses of high-speed compressible turbulence

    NASA Astrophysics Data System (ADS)

    Towery, Colin; Darragh, Ryan; Poludnenko, Alexei; Hamlington, Peter

    2016-11-01

    Interactions between high-speed turbulence and flames (or chemical reactions) are important in the dynamics and description of many different combustion phenomena, including autoignition and deflagration-to-detonation transition. The probability of these phenomena to occur depends on the magnitude and spectral content of turbulence fluctuations, which can impact a wide range of science and engineering problems, from the hypersonic scramjet engine to the onset of Type Ia supernovae. In this talk, we present results from new direct numerical simulations (DNS) of homogeneous isotropic turbulence with turbulence Mach numbers ranging from 0 . 05 to 1 . 0 and Taylor-scale Reynolds numbers as high as 700. A set of detailed analyses are described in both Eulerian and Lagrangian reference frames in order to assess coherent (structural) and incoherent (stochastic) thermodynamic flow features. These analyses provide direct insights into the thermodynamics of strongly compressible turbulence. Furthermore, presented results provide a non-reacting baseline for future studies of turbulence-chemistry interactions in DNS with complex chemistry mechanisms. This work was supported by the Air Force Office of Scientific Research (AFOSR) under Award No. FA9550-14-1-0273, and the Department of Defense (DoD) High Performance Computing Modernization Program (HPCMP) under a Frontier project award.

  13. Characterization of a liquid-filled turbulence simulator

    NASA Astrophysics Data System (ADS)

    Davis, Christopher C.; Zhang, Yimin; Plett, Mark L.; Polak-Dingels, Penelope; Barbier, Pierre R.; Rush, David W.

    1998-10-01

    The development of high performance line-of-sight optical communication links through the turbulent atmosphere is facilitated by laboratory tests of schemes involving adaptive optics, beam tracking, modulation and coding, aperture averaging, fading statistics, and transmitter/receiver diversity. A water-filled turbulence tube has been implemented to simulate, in some respects, the effects produced on a laser beam when it propagates several kilometers through the air. This tube is being used to investigate on a laboratory scale: aperture averaging, fluctuation statistics, optical path difference, high data rate modulation, and various coding schemes. The liquid- filled turbulence tube causes fluctuations on a slower time scale than does the atmosphere. At low turbulence levels it produces log-normal fluctuation statistics, causes tip-tilt errors similar to those previously observed for atmospheric paths, and has already allowed evaluation of aperture averaging and fade statistics. It also allows the testing of various technological schemes to deal with atmospheric turbulence effects without any specific assumptions, such as weak Kolmogorov turbulence, being built into the model.

  14. Turbulence Spectra and Eddy Diffusivity over Forests.

    NASA Astrophysics Data System (ADS)

    Lee, Xuhui

    1996-08-01

    The main objectives of this observational study are to examine the stability dependence of velocity and air temperature spectra and to employ the spectral quantities to establish relations for eddy diffusivity over forests. The datasets chosen for the analysis were collected above the Browns River forest and the Camp Borden forest over a wide range of stability conditions.Under neutral and unstable conditions the nondimensional dissipation rate of turbulent kinetic energy (TKE) over the forests is lower than that from its Monin-Obukhov similarity (MOS) function for the smooth-wall surface layer. The agreement is somewhat better under stable conditions but a large scatter is evident. When the frequency is made nondimensional by the height of the stand (h) and the longitudinal velocity at this height (uh, the Kaimal spectral model for neutral air describes the observations very well. The eddy diffusivity formulation K = c 4w/ provides a promising alternative to the MOS approach, where w is the standard deviation of the vertical velocity and TKE dissipation rate. Current datasets yield a constant of 0.43 for c for sensible heat in neutral and stable air, a value very close to that for the smooth-wall surface layer. It is postulated that c is a conservative parameter for sensible heat in the unstable air, its value probably falling between 0.41 and 0.54. In the absence of data, it is possible to estimate K from measurements of the local mean wind u and air stability. As a special case, it is shown that K = 0.27(uh/uh)w under neutral stability. This relation is then used to establish a profile model for wind speed and scalar concentration in the roughness sublayer. The analysis points out that uh and h are important scaling parameters in attempts to formulate quantitative relations for turbulence over tall vegetation.

  15. Mixing and diffusion in intermittent overturning turbulence

    NASA Astrophysics Data System (ADS)

    Redondo, Jose M.; Mahjoub, Otman B.; Gonzalez-Nieto, Pilar L.; Lawry, Andrew

    2014-05-01

    of scales. The method involving the multi-fractal dimension measurements is much more elaborated and seems to have a better theoretical justification in the sense that it is possible that different concentrations showing different fractal dimensions may be due to different levels of intermittency (and thus different spectra, which are not generally in equilibrium as dscribed by[9,10]. Using topological descriptors we can establish now a theoretical baseline pattern for the turbulence behaviour that is reflected in the different structures (volume fraction, velocity, vorticity, helicity) we can thus obtain a classification relating D3 and the integral of the different fractal dimensions D2 for different levels of scalar (volume fraction reaction intensity or temperature). [5,8,11] Vorticity evolution is more smooth and quite different than that of volume fraction or density and these seem also different for the RT and RM instability driven mixing showing a wider range of even higher mixing efficiencies 0- 0.66 Thanks to European Union project ERBIC15-CT96-0111 Multi-scale complex fluid flows and interfacial phenomena (PITN-GA-2008-214919). ERCOFTAC and GenCat. grant 2001SGR00221. [1] Mahjoub O.B., Redondo J.M. and Babiano A. (2000) Hyerarchy flux in nonhomogeneous flows in Turbulent diffusion in the environment Eds. Redondo J.M. and Babiano A. 249-260. . [2] Dalziel, S. B.,(1994) Perturbations and coherent flow in Rayleigh-Taylor instability: in 4th International Workshop on the Physics of Compressible Turbulent Mixing, ed. P. F. Linden, D. L. Youngs, & S. B. Dalziel; 32-41. [3] Linden, P. F., Redondo, J. M., and Youngs, D. (1994) Molecular mixing in Rayleigh-Taylor instability, J. Fluid Mech. 265, 97-124 [4] Vindel, J.M., Yague, C. and Redondo, J.M. Nuovo Cimento (2008) 31, [5]Redondo J.M. (1993) Fractal models of density interfaces. Wavelets, Fractals and Fourier transforms. (Eds.) M. Farge, J.C.R. Hunt and J.C. Vassilicos. 353-370. IMA number 43, Clarendon Press

  16. [Splenic abscess and cat-scratch disease].

    PubMed

    Valdesoiro Navarrete, L; Pineda Solas, V; Martín Martín, C; Sanfeliu Sala, I; Cabezas Maspoch, R M; Sánchez Oespina, M

    2001-10-01

    Cat-scratch disease is caused by a Gram-negative bacillus known as Bartonella henselae. This disease is usually benign and causes regional adenitis that does not require treatment. However, some patients develop more serious atypical forms of the disease including prolonged systemic illness with hepatic and splenic abscesses.A 14-year-old girl was admitted to hospital with a 12-day history of persistent high fever and abdominal pain. Ultrasonography and computerized tomography of the abdomen revealed splenic abscesses. These findings, together with an antecedent of cat exposure, led to the suspicion of cat-scratch disease, which was confirmed by serology. The girl was treated with intramuscular ceftriaxone and clinical evolution was favorable. Splenic cat-scratch disease is infrequent. Cat-scratch disease sometimes presents as fever of unknown origin and consequently this disease should be considered in the differential diagnosis of prolonged fever. Although evolution is usually favorable, antibiotic therapy is recommended in systemic manifestations of cat-scratch disease.

  17. High-Speed Turbulent Reacting Flows: Intrinsic Flame Instability and its Effects on the Turbulent Cascade

    NASA Astrophysics Data System (ADS)

    Poludnenko, Alexei

    2016-11-01

    Turbulent reacting flows are pervasive both in our daily lives on Earth and in the Universe. They power modern society being at the heart of many energy generation and propulsion systems, such as gas turbines, internal combustion and jet engines. On astronomical scales, thermonuclear turbulent flames are the driver of some of the most powerful explosions in the Universe, knows as Type Ia supernovae. Despite this ubiquity in Nature, turbulent reacting flows still pose a number of fundamental questions often exhibiting surprising and unexpected behavior. In this talk, we will discuss several such phenomena observed in direct numerical simulations of high-speed, premixed, turbulent flames. We show that turbulent flames in certain regimes are intrinsically unstable even in the absence of the surrounding combustor walls or obstacles, which can support the thermoacoustic feedback. Such instability can fundamentally change the structure and dynamics of the turbulent cascade, resulting in a significant (and anisotropic) redistribution of kinetic energy from small to large scales. In particular, three effects are observed. 1) The turbulent burning velocity can develop pulsations with significant peak-to-peak amplitudes. 2) Unstable burning can result in pressure build-up and the formation of pressure waves or shocks when the flame speed approaches or exceeds the speed of a Chapman-Jouguet deflagration. 3) Coupling of pressure and density gradients across the flame can lead to the anisotropic generation of turbulence inside the flame volume and flame acceleration. We extend our earlier analysis, which relied on a simplified single-step reaction model, by demonstrating existence of these effects in realistic chemical flames (hydrogen and methane) and in thermonuclear flames in degenerate, relativistic plasmas found in stellar interiors. Finally, we discuss the implications of these results for subgrid-scale LES combustion models. This work was supported by the Air Force

  18. The interaction of high-speed turbulence with flames: Turbulent flame speed

    SciTech Connect

    Poludnenko, A.Y.; Oran, E.S.

    2011-02-15

    Direct numerical simulations of the interaction of a premixed flame with driven, subsonic, homogeneous, isotropic, Kolmogorov-type turbulence in an unconfined system are used to study the mechanisms determining the turbulent flame speed, S{sub T}, in the thin reaction zone regime. High intensity turbulence is considered with the r.m.s. velocity 35 times the laminar flame speed, S{sub L}, resulting in the Damkoehler number Da=0.05. The simulations were performed with Athena-RFX, a massively parallel, fully compressible, high-order, dimensionally unsplit, reactive-flow code. A simplified reaction-diffusion model, based on the one-step Arrhenius kinetics, represents a stoichiometric H{sub 2}-air mixture under the assumption of the Lewis number Le=1. Global properties and the internal structure of the flame were analyzed in an earlier paper, which showed that this system represents turbulent combustion in the thin reaction zone regime. This paper demonstrates that: (1) The flame brush has a complex internal structure, in which the isosurfaces of higher fuel mass fractions are folded on progressively smaller scales. (2) Global properties of the turbulent flame are best represented by the structure of the region of peak reaction rate, which defines the flame surface. (3) In the thin reaction zone regime, S{sub T} is predominantly determined by the increase of the flame surface area, A{sub T}, caused by turbulence. (4) The observed increase of S{sub T} relative to S{sub L} exceeds the corresponding increase of A{sub T} relative to the surface area of the planar laminar flame, on average, by {approx}14%, varying from only a few percent to as high as {approx}30%. (5) This exaggerated response is the result of tight flame packing by turbulence, which causes frequent flame collisions and formation of regions of high flame curvature >or similar 1/{delta}{sub L}, or ''cusps,'' where {delta}{sub L} is the thermal width of the laminar flame. (6) The local flame speed in the cusps

  19. Constitutive expression of catABC genes in the aniline-assimilating bacterium Rhodococcus species AN-22: production, purification, characterization and gene analysis of CatA, CatB and CatC.

    PubMed

    Matsumura, Eitaro; Sakai, Masashi; Hayashi, Katsuaki; Murakami, Shuichiro; Takenaka, Shinji; Aoki, Kenji

    2006-01-01

    The aniline-assimilating bacterium Rhodococcus sp. AN-22 was found to constitutively synthesize CatB (cis,cis-muconate cycloisomerase) and CatC (muconolactone isomerase) in its cells growing on non-aromatic substrates, in addition to the previously reported CatA (catechol 1,2-dioxygenase). The bacterium maintained the specific activity of the three enzymes at an almost equal level during cultivation on succinate. CatB and CatC were purified to homogeneity and characterized. CatB was a monomer with a molecular mass of 44 kDa. The enzyme was activated by Mn2+, Co2+ and Mg2+. Native CatC was a homo-octamer with a molecular mass of 100 kDa. The enzyme was stable between pH 7.0 and 10.5 and was resistant to heating up to 90 degrees C. Genes coding for CatA, CatB and CatC were cloned and named catA, catB and catC respectively. The catABC genes were transcribed as one operon. The deduced amino acid sequences of CatA, CatB and CatC showed high identities with those from other Gram-positive micro-organisms. A regulator gene such as catR encoding a regulatory protein was not observed around the cat gene cluster of Rhodococcus sp. AN-22, but a possible relic of catR was found in the upstream region of catA. Reverse transcriptase-PCR and primer extension analyses showed that the transcriptional start site of the cat gene cluster was located 891 bp upstream of the catA initiation codon in the AN-22 strain growing on both aniline and succinate. Based on these data, we concluded that the bacterium constitutively transcribed the catABC genes and translated its mRNA into CatA, CatB and CatC.

  20. Preclinical development of CAT-354, an IL-13 neutralizing antibody, for the treatment of severe uncontrolled asthma

    PubMed Central

    May, RD; Monk, PD; Cohen, ES; Manuel, D; Dempsey, F; Davis, NHE; Dodd, AJ; Corkill, DJ; Woods, J; Joberty-Candotti, C; Conroy, LA; Koentgen, F; Martin, EC; Wilson, R; Brennan, N; Powell, J; Anderson, IK

    2012-01-01

    BACKGROUND AND PURPOSE IL-13 is a pleiotropic Th2 cytokine considered likely to play a pivotal role in asthma. Here we describe the preclinical in vitro and in vivo characterization of CAT-354, an IL-13-neutralizing IgG4 monoclonal antibody (mAb), currently in clinical development. EXPERIMENTAL APPROACH In vitro the potency, specificity and species selectivity of CAT-354 was assayed in TF-1 cells, human umbilical vein endothelial cells and HDLM-2 cells. The ability of CAT-354 to modulate disease-relevant mechanisms was tested in human cells measuring bronchial smooth muscle calcium flux induced by histamine, eotaxin generation by normal lung fibroblasts, CD23 upregulation in peripheral blood mononuclear cells and IgE production by B cells. In vivo CAT-354 was tested on human IL-13-induced air pouch inflammation in mice, ovalbumin-sensitization and challenge in IL-13 humanized mice and antigen challenge in cynomolgus monkeys. KEY RESULTS CAT-354 has a 165 pM affinity for human IL-13 and functionally neutralized human, human variant associated with asthma and atopy (R130Q) and cynomolgus monkey, but not mouse, IL-13. CAT-354 did not neutralize human IL-4. In vitro CAT-354 functionally inhibited IL-13-induced eotaxin production, an analogue of smooth muscle airways hyperresponsiveness, CD23 upregulation and IgE production. In vivo in humanized mouse and cynomolgus monkey antigen challenge models CAT-354 inhibited airways hyperresponsiveness and bronchoalveolar lavage eosinophilia. CONCLUSIONS AND IMPLICATIONS CAT-354 is a potent and selective IL-13-neutralizing IgG4 mAb. The preclinical data presented here support the trialling of this mAb in patients with moderate to severe uncontrolled asthma. PMID:21895629