# Turbulence Modeling

AcuSolve supports a variety of turbulence models for fluid flow simulations.

For steady state simulations the Reynolds-averaged Navier-Stokes equations are solved to arrive directly at the time averaged flow field. In case of transient simulations the governing equations are integrated in time to yield an accurate description of the flow field. There are also many different turbulence closure methods available for each type of simulation.

The various turbulence models used in AcuSolve are:
One Equation and Two Equation Models
Spalart-Allmaras (SA) turbulence model
Shear Stress Transport (SST) turbulence model
$k-\omega$ turbulence model
$k-\epsilon$ model
RNG $k-\epsilon$ model
Realizable $k-\epsilon$ model
Detached Eddy Simulation (DES) Models
SA – DES
SST – DES
Dynamic DES (DDES)
Large Eddy Simulation (LES) Models
Classical (Smaroginsky) model
Dynamic subgrid LES model

## Turbulent Boundary Layer Modeling

AcuSolve also offers three approaches for the simulation of turbulent boundary layer. These approaches involve setting the turbulence laws close to the wall and are described as follows:
Fully Resolved
This approach integrates equations directly to the wall and uses near wall damping functions to produce appropriate behavior.
Wall Function
This approach uses a wall model based on the standard Law of the Wall for turbulent boundary layers.
Running Average Wall Function
This approach enforces the Law of the Wall on the running average flow field.

The wall functions used in AcuSolve are valid through the viscous sublayer and the buffer layer and have the advantage of having no lower bound limit. The upper bound limit for $y+$ is 300.