Hi,

Does anybody know how to carry out URANS simulations? Is it just a case of picking your RANS turbulence model then selecting the unsteady formulation? The Fluent manual is useless in this regard.

Then I assume you carry out timestep size changes until you get a good solution? Hope you can help...

Regards,

Carlos.

yes you are right, you pick a RANS model and use the unsteady solver. however, care must be tafen when adjusting the time step size. the time step should be larger than the turbulence scales turn over time and also small enough to capture the unsteady behaviour of the mean flow. this to ensure that the turbulence eddies are modeled and the unsteady behaviour of the mean flow is resolved. you should check the corresponding literature to make the appropriate choice of this time step

Thats great, many thanks!