水流绕过二维方形障碍物的湍流数值模拟

采用了混合有限分析求解方法对湍流绕过二维方形障碍物进行了数值模拟,模拟雷诺应力项时采用了布辛涅斯克假定.采用了k-ε双层模型进行计算,通过与文献中的实验结果及数值计算结果的比较验证了本计算方法的有效性.模拟结果表明k-ε双层模型较壁面函数法预测湍流绕过方形障碍物时更为准确;障碍物高度及流动条件不变时(Re=1.4×104,H=1.0),随着方形障碍物长度的变化,障碍物上游的旋涡Ⅰ的长度基本上没有变化,而在障碍物的下游当L/H≥4时旋涡Ⅱ的长度也基本上保持不变.

Numerical Prediction of Turbulent Flow past a 2D Surface-mounted Rib

A numerical study was performed for investigating the turbulent flow over a surface-mounted two-dimensional rib using Hybrid Finite Analytic Method (HFAM).The Boussinesq approximation had been used for modeling of the Reynolds stress. A two-equation k-ε model with two-layer model was employed. The validity of the numerical method was tested by comparison the numerical predictions with experimental results and numerical simulation results available in literatures, and a good agreement was obtained. The simulation results showed that the two-layer model was suit for modeling the turbulent flow over a square rib and was more accurate than wall function method. Numerical simulation results indicated that upstream of the rib, the length of vortex Ⅰ almost had no change with varying rib lengths under the same rib height and flow conditions ( Re = 1.4 × 104, H = 1.0), downstream of the rib, if L/H ≥ 4 the length of vortex Ⅱ keeps almost unchanged for the varying lengths.