旋转体系中湍流的LBM模拟
Lattice-Boitzmann Investigation of Rotating Turbulence
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摘要: 采用基于多松弛时间因子的格子Boltzmann方法对旋转体系中的湍流进行数值研究,考察Rossby数和Ekman数对湍流的影响,包括湍流能量及其耗散率、速度、涡结构及湍流的耗散尺度即Kolmorogov尺度和积分尺度等.研究表明,系统的旋转延缓了湍流能量的衰减速率,逐步破坏初始涡结构的均匀性,与旋转方向相反的涡逐步被抑制,并最终形成若干与旋转同向的涡柱.结果还表明,系统旋转越快,湍流的耗散尺度越小而积分尺度越大.Abstract: Turbulence in the presence of rotation is numerically investigated with MRT-lattice Bohzmann method. Influence of rotation (Rossby number and Ekman number) on turbulence is studied in detail. Numerical results include turbulence energy, dissipation rate, iso-surface of velocity, vortex structure, dissipation length and integral length and so on. It shows that rotation slows down turbulence energy decaying rate. Moreover, the initial homogeneity of turbulence is broken down in the presence of rotation. Vortices rotating in opposite direction of the system are suppressed gradually and columnar vortices appear rotating in the same direction of the system eventually. In addition, it was found that Kolmogorov length decreases as rotation increases while integral length increases.