RANS, URANS, and DES turbulence Comparison modeling on NACA 0012 AOA25DEG Vorticity | CFD Support

RANS, URANS, and DES turbulence Comparison modeling on NACA 0012 AOA25DEG Vorticity | CFD Support
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RANS stands for Reynolds-Averaged Navier-Stokes. It is a method that averages the flow variables over time to obtain a mean flow field and then models the effect of turbulence using additional equations for the turbulent fluctuations. RANS models are computationally efficient and widely used for industrial applications, but they have limitations in capturing complex flow features and unsteady phenomena.
URANS stands for Unsteady Reynolds-Averaged Navier-Stokes. It is a method that solves the RANS equations in a time-dependent manner, allowing for some unsteady effects to be captured. URANS models are more expensive than RANS models, but they can provide more accurate results for flows with large-scale periodic fluctuations, such as vortex shedding or oscillating jets.
DES stands for Detached-Eddy Simulation. It is a hybrid method that combines RANS and LES (see below) in different regions of the flow domain. DES uses RANS near solid boundaries where the grid resolution is coarse, and switches to LES in regions where the flow is detached and the grid is fine enough to resolve the large eddies. DES models are less costly than LES models, but they can suffer from numerical issues at the interface between RANS and LES zones.