# Large eddy simulation

The **Large Eddy Simulation** ( **LES** , also called **coarse structure ****simulation** in German ) is a method for the numerical calculation of turbulent flows , i.e. those with large Reynolds numbers .

For this purpose, the Navier-Stokes equations are filtered in terms of location and time with a low pass . In this way, the large eddy structures (ie the **large eddies** ) can be calculated directly, the small structures are mapped using a fine structure model.

Thus, the expressiveness and computation time is between the direct numerical simulation (all flow properties are calculated, the required computing time is essential for the normal application to high) and the solution of the RANS equations ( **R** eynolds- **A** veraged- **N** avier- **S** Stokes; it only a time average is calculated, but the computing time is significantly less than with the coarse structure simulation or even the direct numerical simulation).

The Large Eddy Simulation was originally invented by meteorologists who have always had to calculate currents with very large Reynolds numbers.

## literature

- Joel H. Ferziger, Milovan Peric: Numerical Fluid Mechanics . Springer-Verlag, Berlin / Heidelberg 2008, ISBN 978-3-540-67586-0 .