The objective of this paper is to present a new Large Eddy Simulation (LES) model obtained by filtering a generalized version of the Navier–Stokes equations with nonlinear viscosity. This new model is a generalization of the model introduced in Rodríguez and Taboada-Vázquez (2017).

The new LES model, in which viscosity has been substituted by a nonlinear function of the strain rate tensor, has been implemented and validated using FreeFem++ codes. The numerical predictions have been compared with analytical solutions of the Navier–Stokes equations and it was found that the present model provides a more accurate approximation of the exact solution than that obtained by Direct Numerical Simulation (DNS) of the Navier–Stokes equations, even using a coarser mesh.

The model has also been validated by studying the unsteady flow over a backward-facing step. In this case, our numerical predictions have been compared with the experimental measurements reported by Armaly et al. (1983) and the numerical results obtained by Chacón and Lewandowski (2014). The new model performs satisfactorily in predicting these flows too.

本文的目的是提出一种新的大涡模拟（LES）模型，该模型是通过过滤具有非线性粘度的Navier–Stokes方程的广义形式而获得的。这个新模型是Rodríguez和Taboada-Vázquez（2017）中引入的模型的概括。

使用FreeFem ++代码实现并验证了新的LES模型，在该模型中，粘度已被应变率张量的非线性函数代替。将数值预测与Navier–Stokes方程的解析解进行了比较，发现与Navier–Stokes方程的直接数值模拟（DNS）相比，本模型提供了更精确的精确解近似。使用较粗的网格。

该模型还通过研究后向步骤中的非稳态流动得到了验证。在这种情况下，我们的数值预测已经与Armaly等人报道的实验测量结果进行了比较。（1983）和Chacón和Lewandowski（2014）获得的数值结果。新模型在预测这些流量方面也令人满意。