Minimum-dissipation model for large-eddy simulation in OpenFoam -A study on channel flow, periodic hills and flow over cylinder

TL;DR

This study evaluates the minimum-dissipation sub-grid model in OpenFOAM for turbulent flows, demonstrating its accuracy and efficiency across channel, cylinder, and hill flows, with particular emphasis on discretization schemes and mesh resolution.

Contribution

It introduces the static QR model with a specific constant, showing its effectiveness without wall damping and highlighting the benefits of symmetry-preserving discretizations in LES simulations.

Findings

QR model performs as well as dynamic models with lower cost

Symmetry-preserving discretization outperforms standard methods at high Reynolds numbers

Model constant C=0.024 yields optimal accuracy across flow cases

Abstract

The minimum-dissipation model is applied to turbulent channel flows up to $Re_\tau = 2000$, flow past a circular cylinder at $Re=3900$, and flow over periodic hills at $Re=10595$. Numerical simulations are performed in OpenFOAM which is based on finite volume methods for discretizing partial differential equations. We use both symmetry-preserving discretizations and standard second-order accurate discretization methods in OpenFOAM on structured meshes. The results are compared to DNS and experimental data. The results of channel flow mainly demonstrate the static QR model performs equally well as the dynamic models while reducing the computational cost. The model constant $C=0.024$ gives the most accurate prediction, and the contribution of the sub-grid model decreases with the increase of the mesh resolution and becomes very small (less than 0.2 molecular viscosity) if the fine meshes are used. Furthermore, the QR model is able to predict the mean and rms velocity accurately up to $Re_\tau = 2000$ without a wall damping function. The symmetry-preserving discretization outperforms the standard OpenFOAM discretization at $Re_\tau=1000$. The results for the flow over a cylinder show that mean velocity, drag coefficient, and lift coefficient are in good agreement with the experimental data. The symmetry-preserving scheme with the QR model predicts the best results. The various comparisons carried out for flows over periodic hills demonstrate the need to use the symmetry-preserving discretization or central difference schemes in OpenFOAM in combination with the minimum dissipation model. The model constant of $C=0.024$ is again the best one.