湍流热对流的三维数值模拟
首发时间:2012-12-21
摘要:Rayleigh-B'enard湍流热对流系统是研究对流问题的经典流体力学模型,数值模拟在相关的研究工作中具有不可替代的作用。近年来发展起来的格子Boltzmann方法为湍流问题的大规模数值模拟提供了一种高效的技术手段。本文用格子Boltzmann方法对Rayleigh-B'enard湍流热对流进行了三维数值模拟,在竖直方向上采用非平衡外推边界条件,在水平方向上采用周期性边界条件,当Prandtl数为1.07时,Rayleigh数的取值分布在一个较大的数量级区间。数值模拟结果给出了包括对流开始、振荡、混沌、转捩、软湍流及硬湍流等区域的温度场分布,这将有助于理解湍流热对流模式随Rayleigh数变化的规律。
关键词: 流体力学 湍流热对流 数值模拟 格子Boltzmann方法
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Numerical simulation of turbulent convection in three dimensions
Abstract:Rayleigh-B'enard turbulent convection is a classical fluid problem in the research of convection, wherein numerical simulation plays an indispensable role. Recently the lattice Boltzmann method has developed into a highly efficient approach in the investigation of turbulence by large scale numerical simulation. In this paper, the turbulent Rayleigh-B'enard convection is simulated by the Lattice Boltzmann method. The non-equilibrium extrapolation boundary condition is employed in the vertical direction and the periodical boundary condition in the horizontal direction. The Prandtl number is 1.07 and the Rayleigh number ranges in several orders of magnitude. The distribution of temperature field in different regimes is given, including the onset, oscillatory, chaotic, transition, soft-turbulence and hard-turbulence. This result is helpful in understanding the dependence of convection patterns on the Rayleigh number.
Keywords: fluid dynamics turbulent thermal convection numerical simulation lattice Boltzmann method
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