2020 |
Browne LWB, Antonia RA, Rajagopalan S, Chambers AJ, 'Interaction region of a two-dimensional turbulent plane jet in still air. (2020)
The paper describes an experimental study to investigate the velocity and temperature fields in the interaction region of a two dimensional turbulent plane jet in still air. The e... [more]
The paper describes an experimental study to investigate the velocity and temperature fields in the interaction region of a two dimensional turbulent plane jet in still air. The experimental procedure is briefly described and the velocity and temperature variations plotted on graphs. A discussion is made, and conclusions proposed, as the link between the coherent structures observed in the mixing layer and those that were found in the self preserving far field. (A.J.)
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2013 |
Rajagopalan S, Antonia RA, Djenidi L, 'Effect of mesh grids on the turbulent mixing layer of an axisymmetric jet', Heat Transfer Engineering, 34 1216-1225 (2013) [C1]
This article focuses on the effect that two different mesh grids have on the structure of the mixing layer of an axisymmetric jet. Detailed measurements of mean velocity and turbu... [more]
This article focuses on the effect that two different mesh grids have on the structure of the mixing layer of an axisymmetric jet. Detailed measurements of mean velocity and turbulent velocity fluctuations are made with an X hot-wire probe in the range 0.5 = x/d = 10, where x is the longitudinal distance from the nozzle exit plane and d is the nozzle diameter. The grids are introduced at two locations-one location just downstream of the nozzle exit plane and the other location upstream of the nozzle exit plane in order to perturb the nozzle exit boundary layer. One mesh completely covers the nozzle (full mesh or FM) and the other mesh covers the central, high-speed zone (disk mesh or DM). With reference to the undisturbed jet, FM yields a significant reduction in the turbulence intensity and width of the shear layer, whereas DM enhances the turbulence intensity and increases the width of the shear layer. Both grids suppress the formation of the Kelvin-Helmholtz instability in the mixing layer. Results are presented, mainly at x/d = 5 and 6 in both the spectral domain and physical space. In the latter context, second-and third-order structure functions associated with u (the longitudinal velocity fluctuation) and v (the lateral or radial velocity fluctuation) are presented only for the flow perturbed by placing the mesh outside the nozzle. All mesh geometries have a more significant effect on the second-order structure function of u than on that of v. The third-order energy transfer term is affected in such a way that, relative to the undisturbed jet, its peak location is shifted to a smaller scale when FM is used and to a larger scale with DM. This is consistent with our observations that FM reduces the turbulence in the shear layer while DM enhances it. It is suggested that the large-scale vortices that are formed at the edge of the grids play a significant role in the transfer of energy. © 2013 Taylor & Francis Group, LLC.
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Nova |
2012 |
Lee S-J, Kim H-L, Lee J-P, Rajagopalan SR, 'Jet flow characteristics of sinusoidal wavy nozzles', Journal of Mechanical Science and Technology, 26 4007-4016 (2012) [C1]
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Nova |
2007 |
Xu G, Zhou T, Rajagopalan SR, 'Similarity of intermittency characteristics of temperature and transverse velocity', Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 76 (2007) [C1]
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Nova |
2007 |
Rajagopalan SR, Antonia RA, 'Turbulence and drag control in jet and wake flows', Sadhana - Academy Proceedings in Engineering Sciences, 32 133-144 (2007) [C1]
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2007 |
Xu G, Antonia RA, Rajagopalan SR, 'Scaling of mixed longitudinal-transverse velocity structure functions', Europhysics Letters, 79 44001 (2007) [C1]
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Nova |
2005 |
Rajagopalan SR, Antonia RA, 'Flow around a circular cylinder - structure of the near wake shear layer', Experiments in Fluids, 38 393-402 (2005) [C1]
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2004 |
Burattini P, Antonia RA, Rajagopalan SR, Stephens ML, 'Effect of initial conditions on the near-field development of a round jet', Experiments in Fluids, 37 56-64 (2004) [C1]
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2003 |
Olsen JF, Rajagopalan SR, Antonia RA, 'Jet column modes in both a plane jet and a passively modified plane jet subject to acoustic excitation', Experiments in Fluids, 278-287 (2003) [C1]
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2001 |
Xu G, Rajagopalan S, Antonia RA, 'Genetic alterrations of microsatellite markers at chromosome 17 in non-small cell lung cancer', Chinese Journal of Cancer Research, 13 181-184 (2001)
Objective: To analyse the microsatellite instability (MI) and loss of heterozygosity (LOH) in non-small cell lung cancer (NSCLC). Methods: MI and LOH at chromosome 17 were checked... [more]
Objective: To analyse the microsatellite instability (MI) and loss of heterozygosity (LOH) in non-small cell lung cancer (NSCLC). Methods: MI and LOH at chromosome 17 were checked in 35 cases of NSCLC tumor-normal paired tissues using four microsatellite markers TP53 (17p13.1), THRA1 (17q11.2-12), D17S579 (17q12-21) and D17S855 (17q21) by PCR based analysis. Mutations of P53 exons 5-8 were also tested using PCR-single strand conformation polymorphism (PCR-SSCP) and PCR-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. Results: 22 of 35 tumors (62.8%) displayed MI or LOH. 14 tumors (40.0%) exhibited MI, 11 tumors (31.4%) exhibited LOH, while 3 tumors (8.6%) exhibited MI and LOH concurrently. 23 tumors (8.6%) exhibited P53 gene mutations. The frequency of MI or LOH was obviously higher in the early-stage (stages I and II, 78.9%) than in the advanced-stage (stage III, 43.8%). However, the frequency of MI or LOH had no difference either between high-grade (75.0%) and low-grade (52.6%) differentiated NSCLC or between the tumors with P53 mutations (59.1%) and those without P53 mutations (69.2%). No relationship was observed between the presence of MI or LOH and the histologic subtype of NSCLC. Conclusion: The results suggest that MI and LOH at chromosome 17 may play a significant role in the development of NSCLC. The high frequency of MI or LOH in the early-stage tumors indicates that these genetic alterations could occur early during NSCLC development. Our data also show that the genetic alterations of microsatellite at chromosome 17 was not associated with P53 gene mutations.
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2001 |
Xu G, Antonia RA, Rajagopalan SR, 'Sweeping decorrelation hypothesis in a turbulent round jet', Fluid Dynamics Research, 28 311-321 (2001) [C1]
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2000 |
Xu G, Rajagopalan SR, Antonia RA, 'Approach to isotropy in a smooth wall turbulent boundary layer', Fluid Dynamics Research, 26 1-11 (2000) [C1]
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2000 |
Xu G, Antonia RA, Rajagopalan SR, 'Scaling of mixed longitudinal velocity-temperature structure functions', Europhysics Letters, 49 452-458 (2000) [C1]
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2000 |
Xu G, Antonia RA, Rajagopalan SR, 'Scaling of mean temperature dissipation rate', Physics of Fluids, 12 3090-3093 (2000) [C1]
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2000 |
Olsen JF, Rajagopalan S, 'Vortex shedding behind modified circular cylinders', JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS, 86 55-63 (2000)
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1998 |
Rajagopalan SR, Antonia RA, 'Turbulence Reduction in the Mixing Layer of a Plane Jet Using Small Cylinders', Experiments in Fluids, 25 96-103 (1998) [C1]
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1998 |
Rajagopalan SR, Zhou T, Antonia RA, 'Three-component turbulence measurementsusing a four-wire probe', Flow Measurement and Instrumentation, 9 211-216 (1998) [C1]
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1996 |
Antonia RA, Rajagopalan S, Zhu Y, 'Scaling of mean square vorticity in turbulent flows', EXPERIMENTS IN FLUIDS, 20 393-394 (1996)
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1996 |
Rajagopalan S, Ko NWM, 'Velocity and spanwise vorticity measurements in an excited mixing layer of a plane jet', Experiments in Fluids, 20 346-357 (1996)
The mixing layer of a plane jet was subjected to periodic weak excitation at two different frequencies corresponding to shear layer mode (St¿=0.012) and preferred mode (StD=0.36).... [more]
The mixing layer of a plane jet was subjected to periodic weak excitation at two different frequencies corresponding to shear layer mode (St¿=0.012) and preferred mode (StD=0.36). The nozzle exit boundary layer was identical for the unexcited and excited flows. Measurements of mean velocity, longitudinal and lateral velocity fluctuations, Reynolds shear stress and spanwise component of fluctuating vorticity were made over a longitudinal distance x/D of 6 for both the unexcited and the excited flows. Even weak excitation was observed to influence the development of the mixing layer. Under shear layer mode of excitation, the width of the layer and longitudinal turbulence level decrease compared to the naturally developing (unexcited) flow whereas preferred mode of excitation results in increase in the width and turbulence levels. The rms spanwise vorticity showed an increase for shear layer mode of excitation whereas the preferred mode of excitation resulted in a decrease compared to the values in an unexcited flow. Spectra of velocity and vorticity fluctuations exhibited subharmonic peaks, suggesting the possible occurrence of vortex pairing in both unexpected and excited flows. The influence of excitation is found to decrease as x/D increases and is not significant at x/D=6. © 1996 Springer-Verlag.
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1993 |
RAJAGOPALAN S, ANTONIA RA, 'RMS SPANWISE VORTICITY MEASUREMENTS IN A TURBULENT BOUNDARY-LAYER', EXPERIMENTS IN FLUIDS, 14 142-144 (1993)
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1993 |
RAJAGOPALAN S, ANTONIA RA, 'STRUCTURE OF THE VELOCITY-FIELD ASSOCIATED WITH THE SPANWISE VORTICITY IN THE WALL REGION OF A TURBULENT BOUNDARY-LAYER', PHYSICS OF FLUIDS A-FLUID DYNAMICS, 5 2502-2510 (1993)
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1991 |
Raupach MR, Antonia RA, Rajagopalan S, 'Rough-wall turbulent boundary layers', Applied Mechanics Reviews, 44 1-26 (1991)
This review considers theoretical and experimental knowledge of rough-wall turbulent boundary layers, drawing from both laboratory and atmospheric data. The former apply mainly to... [more]
This review considers theoretical and experimental knowledge of rough-wall turbulent boundary layers, drawing from both laboratory and atmospheric data. The former apply mainly to the region above the roughness sublayer (in which the roughness has a direct dynamical influence) whereas the latter resolve the structure of the roughness sublayer in some detail. Topics considered include the drag properties of rough surfaces as functions of the roughness geometry, the mean and turbulent velocity fields above the roughness sublayer, the properties of the flow close to and within the roughness canopy, and the nature of the organized motion in rough-wall boundary layers. Overall, there is strong support for the hypothesis of wall similarity: At sufficiently high Reynolds numbers, rough-wall and smooth-wall boundary layers have the same turbulence structure above the roughness (or viscous) sublayer, scaling with height, boundary-layer thickness, and friction velocity. © 1991 American Society of Mechanical Engineers.
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1990 |
ANTONIA RA, RAJAGOPALAN S, 'DETERMINATION OF DRAG OF A CIRCULAR-CYLINDER', AIAA JOURNAL, 28 1833-1834 (1990)
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1990 |
ANTONIA RA, RAJAGOPALAN S, 'PERFORMANCE OF LATERAL VORTICITY PROBE IN A TURBULENT WAKE', EXPERIMENTS IN FLUIDS, 9 118-120 (1990)
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1984 |
Luxton RE, Bull MK, Rajagopalan S, 'THICK TURBULENT BOUNDRAY LAYER ON A LONG FINE CYLINDER IN AXIAL FLOW.', Aeronautical Journal, 88 186-199 (1984)
Transverse curvature effects in axisymmetric flow on a circular cylinder are discussed. It is deduced that for small delta /a, where delta is the boundary layer thickness and a is... [more]
Transverse curvature effects in axisymmetric flow on a circular cylinder are discussed. It is deduced that for small delta /a, where delta is the boundary layer thickness and a is the cylinder radius, transverse curvature effects are small, for delta /a equals 0(1) the effect is felt mainly in the outer region and for delta /a VM GT TH 1, both the inner and the outer regions are affected. It is argued that the last case can only be achieved experimentally in the laboratory if the radius Reynolds number R//a equals U//1a/v is small and the streamwise Reynolds number R//x equals U//1x/v is large, implying x/a large. New experimental data are presented for this case. The data show that both the mean and turbulent flow field scale on outer variables throughout the layer and, for R//a greater than equivalent to 455, exhibit Reynolds number independence.
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1984 |
RAJAGOPALAN S, ANTONIA RA, 'CONDITIONAL AVERAGES ASSOCIATED WITH THE FINE-STRUCTURE IN A TURBULENT BOUNDARY-LAYER', PHYSICS OF FLUIDS, 27 1966-1973 (1984)
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1984 |
Antonia RA, Chambers AJ, Browne LWB, Rajagopalan S, 'ORGANISED STRUCTURE IN A SLIGHTLY HEATED TURBULENT PLANE JET. 529-534 (1984)
Two-point correlations of temperature fluctuations confirm the existence, in the self-preserving region of a plane jet, of spanwise structures, occurring alternately on opposite s... [more]
Two-point correlations of temperature fluctuations confirm the existence, in the self-preserving region of a plane jet, of spanwise structures, occurring alternately on opposite sides of the centreline. Conditional averages of temperature fluctuations are computed using a selection procedure based on information obtained at several points in space. The averages are compared with those obtained when the selection is based on information at one point in space.
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1984 |
Antonia RA, Rajagopalan S, Fulachier L, 'Comparison of temperature and velocity spectra in a slightly heated turbulent plane jet', AIAA Journal, 22 311-313 (1984)
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1983 |
Antonia RA, Browne LW, Rajagopalan S, Chambers AJ, 'On the organized motion of a turbulent plane jet', Journal of Fluid Mechanics, 134 49-66 (1983)
Measurements of space-time correlations of longitudinal and normal velocity fluctuations and of temperature fluctuations support the existence of counter-rotating spanwise structu... [more]
Measurements of space-time correlations of longitudinal and normal velocity fluctuations and of temperature fluctuations support the existence of counter-rotating spanwise structures appearing alternately on opposite sides of the jet centreline in the self-preserving region of the flow. The frequency of these structures closely satisfies self-preservation. The asymmetric arrangement of the structures is first observed downstream of the position where the jet mixing layers nominally merge but upstream of the onset of self-preservation. Closer to the jet exit, the space¿time correlations indicate the existence of spanwise structures that are symmetrical about the centreline. © 1983, Cambridge University Press. All rights reserved.
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1983 |
ANTONIA RA, BROWNE LWB, CHAMBERS AJ, RAJAGOPALAN S, 'BUDGET OF THE TEMPERATURE VARIANCE IN A TURBULENT PLANE JET', INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, 26 41-48 (1983)
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1983 |
ANTONIA RA, BROWNE LWB, RAJAGOPALAN S, CHAMBERS AJ, 'ON THE ORGANIZED MOTION OF A TURBULENT PLANE JET', JOURNAL OF FLUID MECHANICS, 134 49-66 (1983)
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1983 |
ANTONIA RA, RAJAGOPALAN S, CHAMBERS AJ, 'CONDITIONAL SAMPLING OF TURBULENCE IN THE ATMOSPHERIC SURFACE-LAYER', JOURNAL OF CLIMATE AND APPLIED METEOROLOGY, 22 69-78 (1983)
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1983 |
BROWNE LWB, ANTONIA RA, RAJAGOPALAN S, 'THE SPATIAL DERIVATIVE OF TEMPERATURE IN A TURBULENT-FLOW AND TAYLORS HYPOTHESIS', PHYSICS OF FLUIDS, 26 1222-1227 (1983)
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1982 |
ANTONIA RA, RAJAGOPALAN S, SUBRAMANIAN CS, CHAMBERS AJ, 'REYNOLDS-NUMBER DEPENDENCE OF THE STRUCTURE OF A TURBULENT BOUNDARY-LAYER', JOURNAL OF FLUID MECHANICS, 121 123-140 (1982)
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1982 |
SUBRAMANIAN CS, RAJAGOPALAN S, ANTONIA RA, CHAMBERS AJ, 'COMPARISON OF CONDITIONAL SAMPLING AND AVERAGING TECHNIQUES IN A TURBULENT BOUNDARY-LAYER', JOURNAL OF FLUID MECHANICS, 123 335-362 (1982)
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1982 |
RAJAGOPALAN S, ANTONIA RA, 'USE OF A QUADRANT ANALYSIS TECHNIQUE TO IDENTIFY COHERENT STRUCTURES IN A TURBULENT BOUNDARY-LAYER', PHYSICS OF FLUIDS, 25 949-956 (1982)
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1982 |
RAJAGOPALAN S, SUBRAMANIAN CS, ANTONIA RA, CHAMBERS AJ, 'SPANWISE CORRELATION OF TEMPERATURE IN A TURBULENT BOUNDARY-LAYER', PHYSICS OF FLUIDS, 25 1144-1145 (1982)
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1982 |
ANTONIA RA, RAJAGOPALAN S, BROWNE LWB, CHAMBERS AJ, 'CORRELATIONS OF SQUARED VELOCITY AND TEMPERATURE DERIVATIVES IN A TURBULENT PLANE JET', PHYSICS OF FLUIDS, 25 1156-1158 (1982)
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1982 |
Browne LWB, Antonia RA, Rajagopalan S, Chambers AJ, 'Interaction region of a two-dimensional turbulent plane jet in still air. (1982)
The paper describes an experimental study to investigate the velocity and temperature fields in the interaction region of a two dimensional turbulent plane jet in still air. The e... [more]
The paper describes an experimental study to investigate the velocity and temperature fields in the interaction region of a two dimensional turbulent plane jet in still air. The experimental procedure is briefly described and the velocity and temperature variations plotted on graphs. A discussion is made, and conclusions proposed, as the link between the coherent structures observed in the mixing layer and those that were found in the self preserving far field. (A.J.)
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1981 |
PHANTHIEN N, ANTONIA RA, RAJAGOPALAN S, 'PERTURBATION SOLUTION FOR FLOW BETWEEN A ROTATING-DISK AND A PARALLEL STATIONARY PLATE', JOURNAL DE MECANIQUE, 20 617-625 (1981)
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1981 |
RAJAGOPALAN S, ANTONIA RA, 'PROPERTIES OF THE LARGE STRUCTURE IN A SLIGHTLY HEATED TURBULENT MIXING LAYER OF A PLANE JET', JOURNAL OF FLUID MECHANICS, 105 261-281 (1981)
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1980 |
RAJAGOPALAN S, ANTONIA RA, 'CHARACTERISTICS OF A MIXING LAYER OF A TWO-DIMENSIONAL TURBULENT JET', AIAA JOURNAL, 18 1052-1058 (1980)
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1980 |
PHONGANANT D, ANTONIA RA, CHAMBERS AJ, RAJAGOPALAN S, 'FEATURES OF THE ORGANIZED MOTION IN THE ATMOSPHERIC SURFACE-LAYER', JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 85 424-432 (1980)
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1980 |
RAJAGOPALAN S, ANTONIA RA, 'INTERACTION BETWEEN LARGE AND SMALL-SCALE MOTIONS IN A TWO-DIMENSIONAL TURBULENT DUCT FLOW', PHYSICS OF FLUIDS, 23 1101-1110 (1980)
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1980 |
RAJAGOPALAN S, ANTONIA RA, 'INVESTIGATION OF NATURAL TRANSITION IN THE INLET REGION OF A TWO-DIMENSIONAL DUCT FLOW', PHYSICS OF FLUIDS, 23 1938-1948 (1980)
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1980 |
Phong-Anant D, Antonia RA, Chambers AJ, Rajagopalan S, 'Features of the organized motion in the atmospheric surface layer.', Journal of Geophysical Research, 85 424-432 (1980)
Simultaneous temperature traces at several heights in the first 8 m of the atmospheric surface layer indicate the presence of an organized structure with a spatially coherent upwi... [more]
Simultaneous temperature traces at several heights in the first 8 m of the atmospheric surface layer indicate the presence of an organized structure with a spatially coherent upwind interface characterized by a sharp decrease in temperature. The convecton speed of this interface, obtained by different methods, increases with height and is approximately equal to the local mean wind velocity.- from Authors
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1980 |
Rajagopalan S, Antonia RA, 'Large structure in a heated turbulent mixing layer.', IN: PROC. 7TH AUSTRALASIAN CONF. ON HYDRAULICS & FLUID MECHANICS, PREPRINTS OF PAPERS, (BRISBANE, AUSTRALIA: AUG. 18-22, 1980, 505-508 (1980)
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1979 |
ANTONIA RA, CHAMBERS AJ, PHONGANANT D, RAJAGOPALAN S, 'PROPERTIES OF SPATIAL TEMPERATURE DERIVATIVES IN THE ATMOSPHERIC SURFACE-LAYER', BOUNDARY-LAYER METEOROLOGY, 17 101-118 (1979)
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1979 |
ANTONIA RA, CHAMBERS AJ, PHONGANANT D, RAJAGOPALAN S, SREENIVASAN KR, 'RESPONSE OF ATMOSPHERIC SURFACE-LAYER TURBULENCE TO A PARTIAL SOLAR ECLIPSE', JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 84 1689-1692 (1979)
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1979 |
RAJAGOPALAN S, ANTONIA RA, 'SOME PROPERTIES OF THE LARGE STRUCTURE IN A FULLY-DEVELOPED TURBULENT DUCT FLOW', PHYSICS OF FLUIDS, 22 614-622 (1979)
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1978 |
ANTONIA RA, CHAMBERS AJ, RAJAGOPALAN S, SREENIVASAN KR, FRIEHE CA, 'MEASUREMENTS OF TURBULENT FLUXES IN BASS STRAIT', JOURNAL OF PHYSICAL OCEANOGRAPHY, 8 28-37 (1978)
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1978 |
Antonia RA, Chambers AJ, Rajagopalan S, Screenivasan KR, 'Measurements of turbulent fluxes in Bass Strait.', Journal of Physical Oceanography, 8 28-37 (1978)
Friehe,C Measurements of turbulent momentum, heat and moisture fluxes have been made in Bass Strait from a stable platform, at a height of approximately 5 m above water. Direct me... [more]
Friehe,C Measurements of turbulent momentum, heat and moisture fluxes have been made in Bass Strait from a stable platform, at a height of approximately 5 m above water. Direct measurements of these fluxes are compared with estimates obtained from spectra of velocity, temperature and humidity fluctuations with the use of the inertial dissipation technique. Directly measured momentum and moisture flux values are in reasonable agreement with inertial dissipation values. Thesensible heat flux obtained by the inertial dissipation technique is about twice as large as the directly measured heat flux. The dependence on wind speed of bulk transfer coefficients of momentum, heat and moisture and of variances of velocity and scalar fluctuations is discussed and compared with available data. (A)
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1977 |
Narayanan MAB, Rajagopalan S, Narasimha R, 'Experiments on the fine structure of turbulence', Journal of Fluid Mechanics, 80 237-257 (1977)
Investigations have been carried out of some aspects of the fine-scale structure of turbulence in grid flows, in boundary layers in a zero pressure gradient and in a boundary laye... [more]
Investigations have been carried out of some aspects of the fine-scale structure of turbulence in grid flows, in boundary layers in a zero pressure gradient and in a boundary layer in a strong favourable pressure gradient leading to relaminarization. Using a narrow-band filter with suitable mid-band frequencies, the properties of the fine-scale structure (appearing as high frequency pulses in the filtered signal) were analysed using the variable discriminator level technique employed earlier by Rao, Narasimha & Badri Narayanan (1971). It was found that, irrespective of the type of flow, the characteristic pulse frequency (say Np) defined by Rao et al. was about 0.6 times the frequency of the zero crossings. It was also found that, over the small range of Reynolds numbers tested, the ratio of the width of the fine-scale regions to the Kolmogorov scale increased linearly with Reynolds number in grid turbulence as well as in flat-plate boundarylayer flow. Nearly lognormal distributions were exhibited by this ratio as well as by the interval between successive zero crossings. The values of Np and of the zero-crossing rate were found to be nearly constant across the boundary layer, except towards its outer edge and very near the wall. In the zero-pressure-gradient boundary-layer flow, very near the wall the high frequency pulses were found to occur mostly when the longitudinal velocity fluctuation u was positive (i.e. above the mean), whereas in the outer part of the boundary layer the pulses more often occurred when u was negative. During acceleration this correlation between the fine-scale motion and the sign of u was less marked. © 1977, Cambridge University Press. All rights reserved.
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