Generating turbulence w/ forcing functions
 

Hey all, anyone have experience using forcing functions to generate turbulence? In my compressible LES code, I eventually get negative pressures when I use forcing. Are there any general rules people follow that I need to be aware of?

I've noticed some people use div-free forcing, but that's not a computational possibility with what I'm doing, as it's too expensive.

Usually, turbulence is forced by a statistical Ornstein-Uhlenbeck process. This methods allows to create forcing fields from the solenoidal (div free) to the fully compressible regime. As the forcing is usually only applied to low wave number modes in Fourier space, the computational overhead is very low in both cases.

The following references may be helpful to implement such a method:
http://dx.doi.org/10.1016/0045-7930(88)90013-8
http://nbn-resolving.de/urn/resolver...s2004012514889