Contrasting a novel temporally orientated Hamilton–Jacobi‐equation‐based ILES method with other approaches for a complex geometry flow

Abstract

AbstractFlow and heat transfer inside an idealized electronics system is simulated using large‐eddy simulation (LES)‐related approaches that have been validated for simpler canonical flows. These include: Yoshizawa LES, detached eddy simulation (DES), limited numerical scales (LNS) and other hybrid LES–RANS (Reynolds‐averaged Navier–Stokes) approaches including a new ILES (implicit LES)–RANS method. For the ILES, dissipation from the one legged temporal discretization is used to drain turbulence. The use of differential equations, including the Hamilton–Jacobi and Eikonal, to model turbulence distance functions is explored. The Hamilton–Jacobi is shown to be especially compatible with the zonal RANS–ILES approach and the Eikonal with DES. Performances of the LES‐related methods are compared with explicit algebraic stress unsteady RANS (URANS) results and also measurements. Considering the problem complexity, generally, for all methods, predicted mean velocities and turbulence intensities are in a reasonable agreement with measurements. Average errors are 15 and 25%, respectively. With the exception of the zonal ILES–RANS method, turbulence intensities are under‐predicted. For heat transfer, none of the models performs well giving circa 100% errors. Notably, the LNS performs poorly for both the flow field and heat transfer giving a highly complex RANS–LES interface with inappropriate upstream LES boundary conditions. DES is found impossible to converge. This is partly attributed to the irregular LES–RANS interface arising with the method. All the LES approaches significantly underpredict heat transfer and the URANS over‐predicts. Even the increased flow activity arising from use of the less dissipative ILES element does not prevent the significant heat transfer under‐prediction. Copyright © 2005 John Wiley & Sons, Ltd.