Plasma Models in Hybrid RANS-LES Simulation for Backward Facing Step Flow Control

Abstract

This paper presents a study on the effects of a single discharge barrier dielectric barrier device on the periodic components of the turbulent shear layers and the Reynolds stresses. 3D simulations using improved delayed detached eddy simulation, a hybrid RANS/LES technique, has been used for the study. The geometry for the study is taken from the experimental configurations for this case. The case comprises a turbulent flow over a backward facing step (BFS), where separation is induced after the step edge. The results from the simulations are compared to the experimental data with and without control. The active flow control device is a single dielectric barrier discharge, DBD, plasma actuator located upstream of the step. The effects of quasi-steady and unsteady—or pulsated-plasma actuation using two different phenomenological models are studied. The resulting turbulent structures, Reynolds stresses, and velocity profiles are analysed applying two different models to simulate the plasma actuation. The results for quasi-steady plasma mode show good agreement with the available experimental data and a reduction of the reattachment length. Regarding modulated actuation of the DBD plasma device, three dimensional simulations are carried out and the results also show excellent agreement of the overall behaviour flow when compared to the experimental data.