Investigation on Instability of Rayleigh-Benard Convection Using Lattice Boltzmann Method with a Modified Boundary Condition | ||
| Journal of Computational Applied Mechanics | ||
| مقاله 2، دوره 49، شماره 2، 2018، صفحه 231-239 اصل مقاله (840.06 K) | ||
| نوع مقاله: Research Paper | ||
| شناسه دیجیتال (DOI): 10.22059/jcamech.2017.243410.197 | ||
| نویسندگان | ||
| Mostafa Varmazyar* 1؛ Mohammadreza habibi2؛ Arash Mohammadi1 | ||
| 1Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran | ||
| 2Research Institute of Petroleum Industry, Tehran, Iran | ||
| چکیده | ||
| In this study, the effects of Prandtl number on the primary and secondary instability of the Rayleigh-Benard convection problem has been investigated using the lattice Boltzmann method. Two different cases as Pr=5.8 and 0.7 representing the fluid in liquid and gas conditions are examined. A body forces scheme of the lattice Boltzmann method was presented. Two types of boundary conditions in the presence of body forces are analyzed by the moment method and applied to a Poiseuille flow. Characteristic velocity was set in such a way that the compressibility effects are negligible. The calculations show that the increment of Prandtl number from 0.7 to 5.8 causes to create a secondary instability and onset of the oscillation in the flow field. Results show that at Pr=5.8, when the Rayleigh number is increased, a periodic solution appeared at Ra=48,000. It is observed that the dimensionless frequency ratio for Ra= 105 with Pr=5.8 is around 0.0065. The maximum Nusselt number for Ra = 105 with Pr=5.8 are estimated to be 5.4942. | ||
| کلیدواژهها | ||
| Rayleigh-Benard Convection؛ instability؛ Lattice Boltzmann method؛ Bennett Methodology؛ Dimensionless Frequency Ratio | ||
| مراجع | ||
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