Hello all!

This might be a trivial question but I am rather confused at the moment...

Say I have a large box and inside there is a small box. I'd like to get the small box "moving" in positive x-direction meaning that the box should stay put but it should get the fluid around it moving.

In Fluent this is done by saying that the small solid box has a motion type of "moving reference frame" and giving a value for its translational velocity. As a boundary condition the walls of the small box are given the correct velocity. This way the box itself isn't really moving anywhere but a boundary layer forms around it i.e. it induces movement in the fluid around it.

How do I do this in CFX??

Thanks in advance!

It is similar in CFX as that of in Fluent. Here it is MFR rather MRF, but the concept is same.

Just think in relatve velocity sense. For this you need to :

Additional setting need to be done when setting the domain to be moving domain (translating domain)

Doesn't MFR allow only rotational motion? I've been looking for some informations on transient simulations with moving meshes with large deformations but found nothing.