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.
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.
A comparison of the energy dissipation contours from RSM and rke is shown below.
Energy dissipation map from Reynolds Stress Model (2D)
Energy dissipation map from Reynolds Stress Model (2D)
As shown above, results from the two turbulence models appear similar in terms of the lengths and shapes of the energy dissipation zone and the range of the energy dissipation value, while more detailed minor discrepancies indicates the differences of the two models in terms of their underlying assumptions and methodology.