# Turbulence

Source: https://help.sim-flow.com/documentation/panels/turbulence
Last updated: 2026-10-14

## Introduction

![img 59593b00003e6](https://help.sim-flow.com/documentation/panels/images/turbulence/img_59593b00003e6.png)

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

## Enabling and Disabling Turbulence

![img 59593b6e19b06](https://help.sim-flow.com/documentation/panels/images/turbulence/img_59593b6e19b06.png)

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

## Turbulence Modeling

![img 59593bc38174e](https://help.sim-flow.com/documentation/panels/images/turbulence/img_59593bc38174e.png)

You can select one of three approaches to turbulence modeling:

- **Laminar** - no turbulence modeling is used, applicable for very low velocity flows
- **RANS** - [Reynolds-Averaged Navier-Stokes](https://en.wikipedia.org/wiki/Reynolds-averaged_Navier%E2%80%93Stokes_equations) is the most widely used modeling approach, which offers a balance between accuracy and computational cost
- **LES** - [Large Eddy Simulation](https://en.wikipedia.org/wiki/Large_eddy_simulation) offers improved modeling of large turbulent structures but is very computationally intensive

## RANS Models

![img 59593c20dd59e](https://help.sim-flow.com/documentation/panels/images/turbulence/img_59593c20dd59e.png)

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

![img 59593e208e0d7](https://help.sim-flow.com/documentation/panels/images/turbulence/img_59593e208e0d7.png)

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

![les models](https://help.sim-flow.com/documentation/panels/images/turbulence/les-models.png)

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 the selected model requires it, you can select the 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

![delta methods](https://help.sim-flow.com/documentation/panels/images/turbulence/delta-methods.png)

Currently, available **Delta** calculation methods:

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

**Inputs:**

- **Coefficient**

### Filter Operators

![filter operators](https://help.sim-flow.com/documentation/panels/images/turbulence/filter-operators.png)

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

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

**Inputs:**

- **Width Coefficient**