基于非Favre过滤的大涡模拟

将直接过滤的可压缩Navier-Stokes(NS)方程组作为可压缩湍流大涡模拟方程组.方程组中因过滤产生的高阶相关项用Taylor级数展开近似表达,得到可压缩张量扩散模型.与传统的采用质量加权过滤(Favre过滤)的可压缩大涡模拟方程组相比,由于这种方法没有密度信息的损失,所以能反映真实的密度脉动信息;方程所求量为流场物理量的过滤值,物理意义明确,使大涡模拟结果与直接数值模拟或实验结果更具有可比性.用这种大涡模拟方程组对绕双椭球高超声速湍流进行了模拟,并将所得结果与实验、Baldwin-Lomax(BL)模型及Smagorinsky亚格子模型的结果进行了对比. 

Large eddy simulation based on non-Favre filtering

The equations of motion for large eddy simulation(LES) were obtained by filtering the compressible NS equations.For conventional compressible LES,the Favre filtering was used.This avoids some complexity,but gives rise to difficulties when comparing to experimental data,which is not Favre filtered.A tensor-diffusive model(TDM) for compressible turbulent flow which uses the standard compressible LES filtered variables(non Favre filtering) was proposed.The difficulties mentioned above have been overcome by the TDM approach.The approach is closer to the physics of the problem,because the information of the density is not lost.To validate this approach,the hypersonic flow through an double ellipsoidal sphere was simulated using the non-Favre filtering equations.The results were compared with experiment,as well as the data of BL model and Smagorinsky model.