THREE DIMENSIONAL FINITE ELEMENT ANALYSIS FOR RAYLEIGH-BENARD CONVECTION IN RECTANGULAR ENCLOSURES

• 来源期刊: 力学学报（英文版）
• 学科: 物理学
• 关键词: Rayleigh-Benard convection, finite element method, bifurcation
• 年，卷（期）: 2002,（2）
• 页码范围: 114-125
• 页数: 12页
• 分类号: O3
• 语种: 英文

摘要

The pattern of Rayleigh-Benard convection of air in a rectangular box heated-from-below is studied by numerically solving the three-dimensional timedependent Navier-Stokes equations under the Bonssinesq approximation. Slightly supercritical Rayleigh number was adopted to track the evolutions of flow structure as a function of enclosure's aspect ratio (A = L/H). The flow will asymptotically evolve to different patterns, among which, two possible types of flow pattern are found.One consists of the pair of straight vortex rolls and the other appears as closed vortex rings. The transition between the flow patterns indicates that there exists a flow bifurcation with the variation of container's aspect ratio. In addition, both steady and oscillatory flows have been observed, corresponding to the pair of straight vortex rolls and the vortex ring, respectively. The complexity of flow structure tends to increase with the increasing aspect ratio of the rectangular enclosure.