均匀吸气控制下后台阶流动的数值模拟

Numerical simulation of a backwardfacing step flow controlled by steady suction

摘要:

为检验本文数值方法及其求解策略模拟均匀吸气控制下钝体绕流的可行性，分别采用基于LES（large eddy simulation）方法的DKEM（dynamic kinetic energy subgridscale model）模型和基于RANS（Reynolds averaged NavierStokes）方法的SST（shear stress transport）kω模型对均匀吸气控制下三维后台阶（backwardfacing step，BFS）的流动分离和再附进行了数值模拟． 比较了数值模拟和实验所得的平均风压系数分布和再附长度，结果表明:LES方法在本文精细网格下能得到较精确的预测结果;不同流量系数C^Q的吸气控制均能较显著地减小后台阶流动的环绕区范围和再附长度，改善台阶后的流场结构;随着C^Q绝对值的增加，吸气控制效果逐渐显著．

Abstract:

To verify the feasibility of the numerical methods and solution strategies for simulating the flows around bluff bodies controlled by steady suction, the separation and reattachment over a suctioncontrolled backwardfacing step (BFS) flow is numerically investigated using the dynamic kinetic energy subgridscale model (DKEM) model based on the large eddy simulation (LES) method and the SST k-ω model based on the Reynolds averaged NavierStokes (RANS) method, respectively. Comparisons of the mean pressure coefficient and reattachment length between the numerical simulations and the existed experiment are also conducted to prove the validity. The results indicate that the LES can acquire exact results under the refined grid adopted in the paper. Suction control with any suction flow coefficient C^Q can reduce the recirculation zone and reattachment length, and thus improve the flow fields downstream the step. With the increasing increments of the absolute C^Q,the effect of suction control is more significant. 