Large Eddy Simulation of gravity currents with a high order DG method

TL;DR

This paper presents a high-order Discontinuous Galerkin method for DNS and LES of turbulent gravity currents, demonstrating improved accuracy and model performance over traditional approaches.

Contribution

It introduces a DG-LES approach with built-in filtering, showing advantages over classical models like Smagorinsky in gravity current simulations.

Findings

DG-LES accurately reproduces key features of variable density flows.

Dynamic models outperform Smagorinsky in LES of gravity currents.

Method effectively captures non-Boussinesq lock-exchange phenomena.

Abstract

This work deals with Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES) of turbulent gravity currents, performed by means of a Discontinuous Galerkin (DG) Finite Element method. In particular, a DG-LES approach in which the filter operation is built in the numerical discretization has been employed, similarly to VMS approaches. Numerical simulations of non-Boussinesq lock-exchange benchmark problems show that, in the DNS case, the proposed method allows to correctly reproduce relevant features of variable density flows with gravity. Moreover LES results highlight the excessively high dissipation of the Smagorinsky model with respect to the Germano dynamic procedure, providing a first indication of the superiority of dynamic models in the context of gravity currents.