9 Numerical simulation of convective flows under microgravity conditions

2020 ◽  
pp. 257-340
Keyword(s):  
Numerical Simulation ◽  
Convective Flows ◽  
Microgravity Conditions

High Rayleigh Number Flows in a Cubical Enclosure

2005 ◽  
Author(s):  
Lucas Vargas ◽  
Ikram Ahmed ◽  
David N. Koert
Keyword(s):  
Numerical Simulation ◽  
Rayleigh Number ◽  
Prandtl Number ◽  
Turbulent Flows ◽  
State Of The Art ◽  
Transition To Turbulence ◽  
Computing Technology ◽  
Chaotic Flows ◽  
Convective Flows ◽  
Cubical Enclosure

High Rayleigh number (Ra) natural convective flows in cubical enclosures were investigated using Direct Numerical Simulation (DNS). Here the bottom of the cavity was heated while the top was cooled, each maintained at a different constant temperature, with the sidewalls insulated. The Prandtl number was maintained at 2.5 and the Ra varied between 106 and 108. In order to observe the transition to turbulence with increasing Ra, power spectrum slopes were compared with Kolmogorov’s −5/3 rule for turbulent flows. At the higher Ra studied, the flows showed characteristics typically attributed to “chaotic” flows. However, the transition to full turbulence was not observed, which is expected around Ra ∼ 109 and may not be predicted using DNS with the state-of-the-art computing technology.

STUDY OF CONVECTIVE FLOWS IN THREE-COMPONENT GAS MIXTURES BY THE METHOD OF NUMERICAL SIMULATION

2021 ◽  
Vol 73 (1) ◽  
pp. 103-109
Author(s):  
V.N. Kossov ◽  
◽  
V. Mukamedenkyzy ◽  
Z.Z. Yuldasheva ◽  
A. Khasseinova ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Average Velocity ◽  
Cylindrical Channel ◽  
Gas Mixtures ◽  
Physical Parameters ◽  
Loss Of Stability ◽  
Mechanical Equilibrium ◽  
Splitting Scheme ◽  
Heavy Component ◽  
Convective Flows

The characteristics of convective flows arising in three-component gas mixtures are investigated by the method of numerical simulation. The time variation of the isoconcentration lines of the heavy component of the mixture and the average velocity are considered as characteristics of convective flows. To calculate the characteristics of convective flows arising in a vertical cylindrical channel, we used a numerical model based on the splitting scheme according to physical parameters. It was shown that in three-component gas mixtures, where special diffusion regimes are manifested, non-monotonic distributions of component concentrations and velocities are possible. The time of loss of stability of mechanical equilibrium and the time of developed convective flows are determined.

scholarly journals Concluding remarks

2006 ◽  
Vol 2 (S239) ◽  
pp. 517-522
Author(s):  
Jean-Paul Zahn
Keyword(s):  
Numerical Simulation ◽  
Accretion Disks ◽  
Thermal Convection ◽  
New Techniques ◽  
Spatial And Temporal Scales ◽  
Convective Flows ◽  
The Past ◽  
Wide Range ◽  
Astrophysical Objects ◽  
Substantial Progress

Thermal convection occurs in most objects that populate our Universe, whenever radiation is insufficient to transport the heat because the medium is too opaque. In astrophysical objects convection involves a wide range of spatial and temporal scales - experts call this turbulence - which makes it rather difficult to model. For this reason convection remains one of the major uncertainties when modeling stars and planets, and this is partly true also for accretion disks. However, substantial progress has been achieved during the past years, both in the numerical simulation of convective regions and in the observation of convective flows by various new techniques.

Numerical simulation of droplet deformation in convective flows

AIAA Journal ◽  
1992 ◽  
Vol 30 (5) ◽  
pp. 1290-1297 ◽  
Author(s):  
Zheng-Tao Deng ◽  
San-Mou Jeng
Keyword(s):  
Numerical Simulation ◽  
Droplet Deformation ◽  
Convective Flows
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