# Turbulence

## Introduction

In the **Turbulence** panel you can enable turbulence models appropriate for your simulation.

## Enabling and Disabling Turbulence

In certain situations it can be useful to disable turbulence model at the beginning of simulation. This can be done using the **Enable Turbulence Equations** button and is usually used to stabilize simulation. Turbulence model can be enabled or disabled even while the simulation is still running.

## Turbulence Modeling

You can select one of three approaches to turbulence modelling:

**Laminar**- no turbulence modeling is used, applicable for very low velocity flows**RANS**- Reynolds-Averaged Navier-Stokes is most widely used modeling approach, which offers balance between accuracy and computational cost**LES**- Large Eddy Simulation offers improved modelling of large turbulent structures but is very computationally intensive

## RANS Models

When you select RANS turbulence modeling you will only have to define a **Model** .

Currently available models are:

**\(k-\epsilon\)****\(RNG k-\epsilon\)****\(Realizable k-\epsilon\)****\(Spalart-Allmaras\)****\(k-\omega\)****\(k-\omega SST\)****\(k-\omega SST SAS\)****\(k-kl-\omega\)**

Available models will vary depending on the version of OpenFOAM you are using and the solver that is currently selected.

### Model Constants

Most models require some constants to be specified. You can edit these constants by clicking the **Expand** button. Usually, you should not change the default values.

## LES Models

When you select LES modeling you will be able to specify:

**Model**- LES or DES model to use**Delta**- method for determining cutoff length scale**Filter**– if selected model requires, you can select type of the LES filter

Currently, available LES models:

**\(k-\omega SST DDES\)****\(k-\omega SST IDDES\)****\(k-\omega SST DES\)****\(Spalart-Allmaras DES\)****\(Spalart-Allmaras DDES\)****\(Spalart-Allmaras IDDES\)****\(Smagorinsky\)****\(WALE\)****\(k Equation\)****\(Dynamic k Equation\)**

### Delta Calculation Methods

Currently, available **Delta** calculation methods:

**Cube Root Volume****Max Delta XYZ**

**Inputs:**

**Coefficient**

### Filter Operators

For **Dynamic k Equation** model there are available **Filter** operators:

**Simple****Laplace****Anisotropic**

**Inputs:**

**Width Coefficient**