CFX4中常用模型在复杂流动中适用性分析

目前商用流体力学被广泛用于工业的流动分析,但是对其模拟复杂流动的适用性和精确度等的认识还不够.通过数值计算和实验的对比分析,对CFX4提供的常用的标准k-ε模型、RNGk-ε模型以及低雷诺数k-ε模型在模型参数缺省的情况下计算值的准确性作了较为详细的评价.结果发现,数值计算值的准确性与流动的复杂性有关.对所讨论的两种流动,标准k-ε模型和RNGk-ε模型给出了与实测值较为一致的结果,而低雷诺数k-ε模型与实测结果存在较大出入.因此,在没有实验资料进行模型验证的情况下,标准k-ε模型和RNGk-ε模型可能是一个较好的选择.

Analysis of applicability of models in CFX4 to complex Flow

Today, commercial flow analysis tools are widely used in the industry, but their capacity, efficiency and accuracy to solve complex flow are not so clear. Based on experimental data, a detailed discussion on the accuracy of 4 turbulence models with default model parameters in CFX4 is carried out. It is shown that the predicted accuracy is dependent on the complexity of the flow itself. For the discussed 2 cases, predicted velocities from standard k-ε model and RNG k-ε model, in general, have good agreement with the experiment,while the difference between the measured velocities and the prediction from the low Reynolds number k-ε model is large. However, the predicted vortex structures from these turbulence models are different from the experiment. Therefore,model verification is always necessary for a high accurate numerical analysis of complex flows.Under the situation of lacking of experimental data, the standard k-ε or RNG k-ε models may be a good choice.