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

• Published in: International journal of numerical methods for heat & fluid flow Vol. 29; no. 3; pp. 949 - 980
• Main Authors: Saroha, Sagar, Sinha, Sawan S, Lakshmipathy, Sunil
• Format: Journal Article
• Language: English
• Published: Bradford Emerald Publishing Limited 04.03.2019; Emerald Group Publishing Limited
• Subjects: Acceptability; Anisotropy; Bluff bodies; Boussinesq approximation; Boussinesq equations; Computational fluid dynamics; Computer simulation; Cylinders; Eddy viscosity; Energy; Evaluation; Experiments; Flow control; Flow separation; Flow simulation; Fluid flow; Frameworks; Mathematical models; Methodology; Methods; Navier-Stokes equations; Orientation; Parameters; Reduction; Reynolds number; Tensors; Turbulence; Viscosity; Vortices; OpenFOAM; Non-linear eddy viscosity model; Partially-averaged navier stokes equation
• ISSN: 0961-5539; 1758-6585
• DOI: 10.1108/HFF-09-2018-0529

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 (fk) 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 fk, 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.