An LES Turbulent Inflow Generator using A Recycling and Rescaling Method

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.The present paper describes a recycling and rescaling method for generating turbulent inflow conditions for Large Eddy Simulation. The method is first validated by simulating a turbulent boundary layer and a turbulent mixing layer. It is demonstrated that, with input specification of mean velocities and turbulence rms levels (normal stresses) only, it can produce realistic and self-consistent turbulence structures. Comparison of shear stress and integral length scale indicates the success of the method in generating turbulent 1-point and 2-point correlations not specified in the input data. With the turbulent inlet conditions generated by this method, the growth rate of the turbulent boundary/mixing layer is properly predicted. Furthermore, the method can be used for the more complex inlet boundary flow types commonly found in industrial applications, which is demonstrated by generating non-equilibrium turbulent inflow and spanwise inhomogeneous inflow. As a final illustration of the benefits brought by this approach, a droplet-laden mixing layer is simulated. The dispersion of droplets in the near-field immediately downstream of the splitter plate trailing edge where the turbulent mixing layer begins is accurately reproduced due to the realistic turbulent structures captured by the recycling/rescaling method

Large-eddy simulation of the shock/boundary layer interaction

Bidimensional interaction of an oblique shock with a plane plate has been studied numerically using large eddy simulation (LES) and compared with experimental data. This case represents an idealized model of bidimensional air intake and constitutes a challenge for compressible LES because shock and strong separation are considered. Numerically, a particular attention is given to spatial numerical scheme and to inflow conditions. Numerical results are in good quantitative agreement with experimental results, and LES can now be considered as a predictive tool for such physically complex flow. Mean and fluctuating longitudinal velocity are in very satisfactory agreement with experimental data. Nevertheless, cross term (u'w') appears underestimated. The separated zone is correctly described, and LES can be used for fine study of the physic of such interaction. The dependence of the solution to numerical parameters is studied extensively. The effects of the size of the domain in the spanwise direction, of the resolution in the longitudinal direction, and the presence of a subgrid-scale model do not appear to be deciding