Effects of convection schemes on hybrid RANS-LES calculations

Artikel i vetenskaplig tidskrift, 2018

Nowadays it is commonly accepted to report on convections schemes in the case of Large Eddy Simulations. However, this is still not mandatory for the hybrid Reynolds-Averaged Navier-Stokes (RANS)—LES calculations. Therefore, this paper intends to show that the effects of convection scheme is equally important for hybrid RANS-LES calculations as well as for LES runs. We choose here the Partially-Averaged Navier–Stokes (PANS) model as the representative hybrid RANS-LES model but the conclusions derived in this work are equally applicable to other methods. The aim of the paper is to provide a proper criterion from the employment of higher order differencing schemes. The paper will assess two approaches, namely step functions where central-differencing scheme is used in the regions with a lower unresolved turbulent kinetic energy and a continuous function which depends on the ratio between unresolved and total kinetic energy. The results will be presented for the flow around the square cylinder. Direct numerical simulation (DNS) data and measurements are available for comparisons.