2D simulations with Reynolds Stress turbulence model

Hypothesis and Goals

The Reynolds Stress model(RSM) is the most elaborate turbulence model that FLUENT provides. Abandoning the isotropic eddy-viscosity hypothesis, the RSM closes the Reynolds-averaged Navier-Stokes equations by solving transport equations for the Reynolds stresses, together with an equation for the dissipation rate. This means that five additional transport equations are required in 2D flows.

Since the RSM accounts for the effects of streamline curvature, swirl, rotation, and rapid changes in strain rate in a more rigorous manner than one-equation and two-equation models, it has greater potential to give accurate predictions for 180-degree-turning flow in the hydraulic flocculator.

Simulations using RSM was compared to results from the current k-epsilon realizable (rke) model.

Methods and Procedures

Click here for a Report summary describing all modeling parameters.

Note that as opposed to k-epsilon realizable solver, RSM is quite sensitive to different specification methods of both inlet and outlet boundary conditions.

Results and Discussion

A comparison of the energy dissipation contours from RSM and rke is shown below.

Energy dissipation contour of 2D model, k-epsilon realizable 1.5b

Energy dissipation contour of 3D model with periodic boundary condition, k-epsilon realizable

Further Research

As mentioned above, RSM is quite sensitive to turbulence specification method of both inlet and out boundary conditions, thus more simulation experiments and research on the underlying methodology are needed to investigate about this parameter.