Introduction

Generation of synthetic turbulence at LES inlets can be defined using the cs_user_les_inflow_define user function, and possibly updated using cs_user_les_inflow_update, with cs_user_les_inflow_advanced allowing for finer definition of target statistics the inlet if needed.

Global caracteristics of synthetic turbulence inlets

General settings

The cs_user_les_inflow_define function is the main entry point for LES inflow definitions.

It can be used to set general options, such as the specific checkpoint/restart behavior, as in the following example:

Defining inlet properties

For each LES inlet, the cs_les_inflow_add_inlet must be used.

For example, to use the Batten Method for boundary faces of a zone named INLET_1:

And to use the Synthetic Eddy Method for boundary faces of a zone named INLET_2:

Modifying synthetic turbulence inlets

Updating base characteristics

To update reference velocity, turbulent kinetic energy, or dissipation rate for a given turbulence inlet, the cs_user_les_inflow_update function may be used. It is called automatically for each LES inlet defined previously.

The following example illustrates modifying values for the example zone named INLET_1:

Advanced LES inlet Example 1

Mean velocity, Reynolds stresses an dissipation are deduced from a wall law for the zone named INLET_1 (no modification of the statistics of the flow is provided for the other synthetic turbulence inlets).

Advanced LES Example 2

Reynolds stresses and dissipation at the inlet are computed using the turbulence intensity and standard laws for a circular pipe for for the zone named INLET_1 (no modification of the statistics of the flow is provided for the other synthetic turbulence inlets).