适用于公路隧道湍流的亚滤波尺度模型修正

Modification of Subfilter-scale Model in Large Eddy Simulation for Flow Field in Highway Tunnels

公路隧道流场的复杂性给数值计算带来了极大的困难,动态涡粘性模型和动态混合模型都存在小尺寸涡的耗散过大问题。主要原因在于,公路隧道湍流在壁面附近存在强剪切应力,以致于小尺寸涡的耗散较大,但模型的耗散量不足以使之平衡。湍流能量级串机制的研究表明,在湍流场中,大尺度运动对小尺度运动的细节不敏感。所以,只要亚滤波尺度模型提供了恰当的动能耗散率,大尺度运动的模拟结果就能获得大致正确的统计规律。基于上述思想,文章提出了一种适用于公路隧道流场的涡粘系数模型。该模型能产生恰当的动能耗散率,从而平衡亚滤波尺度运动的能量耗散。经过与模型实测数据和DNS计算结果的对比,验证了其准确性,效果理想。

The complexity of highway tunnel flow field has brought a lot of difficulties to numerical calculation,the problem of excessive dissipation of small-size eddy exists in both the dynamic eddy viscosity model and dynamic mixed model.The main reason is that there is strong shear stress for the turbulence near the wall of highway tunnels, causing large dissipation of small size eddy,but the simulated dissipation in the model is not sufficient to balance it. A study on turbulent energy cascade mechanism shows that the large-scale motion is not sensitive to the details of small-scale motion in the turbulent flow field,and as long as the SFS model provides appropriate kinetic energy dissipation rate,the roughly correct statistical law can be obtained from the simulation results of large scale motion. Based on the above ideas,an eddy viscosity coefficient model for highway tunnel flow field is proposed.The model can generate an appropriate kinetic energy dissipation rate so as to balance the energy dissipation of SFS motion.Its accuracy is verified and the effect is ideal through the comparison of the measured data of model and DNS calculation results.