Numerical simulation the vortex in Couette-Taylor flow of compressible gas
Mathematics. Physics. Mechanics
Moscow Institute of Physics and Technology, 9, Institutskiy per., Dolgoprudny, Moscow region, 141701, Russia
The Couette-Taylor flow in compressible gas is of great importance in theoretical physics as well as for technical applications. There is a variety of research papers on the flow in incompressible gases and liquids considering both theoretical issues and numerical simulation results. However, the number of studies for the compressible flow is limited, despite its increasing applications. The purpose of this paper is to obtain numerical results for the Couette-Taylor flow in compressible gas using the software ANSYS CFX to study the vortex structure within one symmetric couple and the effect of the cylinder surface temperature as well as Reynolds number on the vortex structure and vortex density.
In order to produce reliable results for unlimited coaxial cylinders, the physical model was built to guarantee the length of the cylinders is much bigger than the gap between the two cylinders (100 times in our model). To obtain compressibility properties, air was chosen. The numerical results showed symmetric trajectories of air particles in neighboring vortices, which means the vortices are coupled and each couple contains two symmetric vortices.
The vortex density as well as the vortex structure were studied through the Reynolds number and the cylinder surface temperature. The Reynolds number based on the speed of the inner cylinder changes within the range of 4.104 and 4.105. The temperature is referred to the stagnation temperature. The results show similar dependencies of vortex density on the Reynolds number and on the surface temperature. The density initially increases with the increase of the Reynolds number. After reaching its high, the density drops dramatically before remaining stable despite the increase of Reynolds number.
The same pattern is observed for vortex density and temperature relation. In our model, the surface temperature of the inner cylinder was fixed and the surface temperature of the outside cylinder was changed between one to eight with respect to the stagnation temperature. The vortex density remains unchanged when the surface temperature of the outside cylinder exceeds seven.
Keywords:Couette-Taylor flow, compressibility influence, flow structure
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