Three-Dimensional Rayleigh-Benard Convection of a Rarefied Gas: DSMC and Navier-Stokes Calculations

Abstract

The three-dimensional Rayleigh-Benard convection of a rarefied gas is studied numerically by using DSMC and Navier-Stokes finite difference methods. We present the results obtained in a three-dimensional box with an aspect ratio A=Lx:Ly:Lz at a fixed wall temperature ratio r=Tc/Th=0.1. In general, the three-dimensional results confirm the validity of the zone of convection obtained in the previous author's two-dimensional considerations. A detailed analysis has been performed for Knudsen number Kn=0.02 and A=2:2:1, A=3:3:1, and A= 4:4:1 and different Froude numbers ranged within the zone of convection. As result, a variety of different stable convection patterns in form of rolls and squares has been obtained. For the lowest Knudsen numbers computed, Kn=0.001 and Kn=0.002 , Froude number Fr= 1.0, and a fixed aspect ratio A=2:2:1, an irregular (chaotic) flow in form of unstable polygonal patterns has been observed.

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Document Details

Document Type
Technical Report
Publication Date
Jul 13, 2005
Accession Number
ADA446020

Entities

People

  • C. Cercignani
  • S. K. Stefanov
  • V. M. Roussinov

Organizations

  • Bulgarian Academy of Sciences

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Aspect Ratio
  • Computational Fluid Dynamics
  • Convection
  • Dynamics
  • Flow
  • Fluid Dynamics
  • Fluid Flow
  • Froude Number
  • Gas Dynamics
  • Gases
  • Knudsen Number
  • Rarefied Gas Dynamics
  • Rarefied Gases
  • Simulations
  • Temperature Gradients
  • Three Dimensional
  • Two Dimensional

Fields of Study

  • Physics

Readers

  • Combustion science or combustion engineering.
  • Computational Fluid Dynamics (CFD)
  • Marine Hydrodynamics