scholarly journals SODAR STUDIES OF THE MONSOON TROUGH BOUNDARY LAYER AT JODHPUR (INDIA)

MAUSAM ◽  
2021 ◽  
Vol 44 (1) ◽  
pp. 9-14
Author(s):  
S. P. SINGAL ◽  
B. S. GERA ◽  
V. K. OJHA
Keyword(s):  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Inversion Layer ◽  
Monsoon Trough ◽  
Thermal Plumes ◽  
Preliminary Examination ◽  
Set Up ◽  
Monsoon Dynamics

A monostatic sodar was set up at Jodhpur, the extreme end of the monsoon trot*, to study the thermal boundary layer up to a height of 700 m. This effort was a part of the co-ordinated multi institutional project to study the monsoon dynamics. The usual structures of thermal plumes, ground based stable layers, elevated/multi- layers with or without undulations and dot echoes were seen. However, erosion of the inversion layer normally observed in the morning in the form of a rising layer over land areas was absent all through the period of observation from June to August 1990. In the paper, a study of the observed data in relation to the rainfall activity has been made. A preliminary examination shows that sodar structures may provide addi• tional information, not available normally through the conventional meteorological tools.

Effect of Nanofluid on Heat Transfer Enhancement for Mixed Convection Flow Over a Corrugated Surface

2020 ◽  
Vol 45 (4) ◽  
pp. 373-383
Author(s):  
Nepal Chandra Roy ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Local Nusselt Number ◽  
Richardson Number ◽  
Thermal Boundary Layer ◽  
Volume Fraction ◽  
Convection Flow ◽  
Mixed Convection Flow

AbstractA mathematical model for mixed convection flow of a nanofluid along a vertical wavy surface has been studied. Numerical results reveal the effects of the volume fraction of nanoparticles, the axial distribution, the Richardson number, and the amplitude/wavelength ratio on the heat transfer of Al2O3-water nanofluid. By increasing the volume fraction of nanoparticles, the local Nusselt number and the thermal boundary layer increases significantly. In case of \mathrm{Ri}=1.0, the inclusion of 2 % and 5 % nanoparticles in the pure fluid augments the local Nusselt number, measured at the axial position 6.0, by 6.6 % and 16.3 % for a flat plate and by 5.9 % and 14.5 %, and 5.4 % and 13.3 % for the wavy surfaces with an amplitude/wavelength ratio of 0.1 and 0.2, respectively. However, when the Richardson number is increased, the local Nusselt number is found to increase but the thermal boundary layer decreases. For small values of the amplitude/wavelength ratio, the two harmonics pattern of the energy field cannot be detected by the local Nusselt number curve, however the isotherms clearly demonstrate this characteristic. The pressure leads to the first harmonic, and the buoyancy, diffusion, and inertia forces produce the second harmonic.

scholarly journals Nocturnal Boundary Layer Evolution and Its Impacts on the Vertical Distributions of Pollutant Particulate Matter

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 610
Author(s):  
Yu Shi ◽  
Lei Liu ◽  
Fei Hu ◽  
Guangqiang Fan ◽  
Juntao Huo
Keyword(s):  
Boundary Layer ◽  
Nitrate Concentration ◽  
Inversion Layer ◽  
Mixing Layer ◽  
Early Morning ◽  
Nocturnal Boundary Layer ◽  
Atmospheric Environment ◽  
Considerable Proportion ◽  
Surface Inversion ◽  
Vertical Distributions

To investigate the evolution of the nocturnal boundary layer (NBL) and its impacts on the vertical distributions of pollutant particulates, a combination of in situ observations from a large tethered balloon, remote sensing instruments (aerosol lidar and Doppler wind lidar) and an atmospheric environment-monitoring vehicle were utilized. The observation site was approximately 100 km southwest of Beijing, the capital of China. Results show that a considerable proportion of pollutant particulates were still suspended in the residual layer (RL) (e.g., the nitrate concentration reached 30 μg m−3) after sunset. The NBL height calculated by the aerosol lidar was closer to the top of the RL before midnight because of the pollutants stored aloft in the RL and the shallow surface inversion layer; after midnight, the NBL height was more consistent with the top of the surface inversion layer. As the convective mixing layer gradually became established after sunrise the following day, the pollutants stored in the nocturnal RL of the preceding night were entrained downward into the mixing layer. The early morning PM2.5 concentration near 700 m in the RL on 20 December decreased by 83% compared with the concentration at 13:34 on 20 December at the same height. The nitrate concentration also decreased significantly in the RL, and the mixing down of nitrate from the RL could contribute about 37% to the nitrate in the mixing layer. Turbulence activities still existed in the RL with the bulk Richardson number (Rb) below the threshold value. The corresponding increase in PM2.5 was likely to be correlated with the weak turbulence in the RL in the early morning.

scholarly journals Thermal boundary layer structure in convection with and without rotation

2020 ◽  
Vol 5 (11) ◽  
Author(s):  
Robert S. Long ◽  
Jon E. Mound ◽  
Christopher J. Davies ◽  
Steven M. Tobias
Keyword(s):  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Layer Structure ◽  
Boundary Layer Structure

Stability of a thermal boundary layer in the presence of vibration in weightlessness environment

2011 ◽  
Vol 192 (1) ◽  
pp. 129-134 ◽  
Author(s):  
D. Lyubimov ◽  
T. Lyubimova ◽  
S. Amiroudine ◽  
D. Beysens
Keyword(s):  
Boundary Layer ◽  
Thermal Boundary Layer
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