Evaluation of PANS method in conjunction with non-linear eddy viscosity closure using OpenFOAM

Abstract

Purpose

In recent years, the partially averaged Navier–Stokes (PANS) methodology has earned acceptability as a viable scale-resolving bridging method of turbulence. To further enhance its capabilities, especially for simulating separated flows past bluff bodies, this paper aims to combine PANS with a non-linear eddy viscosity model (NLEVM).

Design/methodology/approach

The authors first extract a PANS closure model using the Shih’s quadratic eddy viscosity closure model [originally proposed for Reynolds-averaged Navier–Stokes (RANS) paradigm (Shih et al., 1993)]. Subsequently, they perform an extensive evaluation of the combination (PANS + NLEVM).

Findings

The NLEVM + PANS combination shows promising result in terms of reduction of the anisotropy tensor when the filter parameter (f_k) is reduced. Further, the influence of PANS filter parameter f on the magnitude and orientation of the non-linear part of the stress tensor is closely scrutinized. Evaluation of the NLEVM + PANS combination is subsequently performed for flow past a square cylinder at Reynolds number of 22,000. The results show that for the same level of reduction in f_k, the PANS + NLEVM methodology releases significantly more scales of motion and unsteadiness as compared to the traditional linear eddy viscosity model (LEVM) of Boussinesq (PANS + LEVM). The authors further demonstrate that with this enhanced ability the NLEVM + PANS combination shows much-improved predictions of almost all the mean quantities compared to those observed in simulations using LEVM + PANS.

Research limitations/implications

Based on these results, the authors propose the NLEVM + PANS combination as a more potent methodology for reliable prediction of highly separated flow fields.

Originality/value

Combination of a quadratic eddy viscosity closure model with PANS framework for simulating flow past bluff bodies.

Citation

Saroha, S., Sinha, S.S. and Lakshmipathy, S. (2019), "Evaluation of PANS method in conjunction with non-linear eddy viscosity closure using OpenFOAM", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 29 No. 3, pp. 949-980. https://doi.org/10.1108/HFF-09-2018-0529