How to run unsteady simulation in OpenFOAM?

usman89 · August 1, 2016, 14:00

Hi

I am doing my thesis on wind turbine wake analysis using OpenFOAM. The method I have to use is a fully resolved rotor method, i.e. direct method with the full turbine model.

So far I have been simulation with RANS approach, k omega SST and SimpleFOAM solver.

However, I have read that I have to do an unsteady analysis, read somewhere that it involves URANS.

Anyone able to shed some light on this please? Or do I simply run RANS approach with a different solver?

Many thanks

U

Tobi · August 12, 2016, 11:26

Unsteady means that you solve in time (you are interested of the time evaluation). Therefore you should use PIMPLE or PISO solver. In the newer versions there is only the xxxPimpleFoam available that can operate in PISO mode too.

A xxxSimpleFoam solver is normaly solving for steady-state and hence we have no time derivative that we take into account. If you don't know if a solver solves for a steady or unsteady problem. Check the equations in the source code and the fvSchemes for ddt and/or d2dt.

August 1, 2016, 14:00	How to run unsteady simulation in OpenFOAM?	#1
usman89 New Member Usman Ashraf Join Date: Jul 2016 Posts: 1 Rep Power: 0	Hi I am doing my thesis on wind turbine wake analysis using OpenFOAM. The method I have to use is a fully resolved rotor method, i.e. direct method with the full turbine model. So far I have been simulation with RANS approach, k omega SST and SimpleFOAM solver. However, I have read that I have to do an unsteady analysis, read somewhere that it involves URANS. Anyone able to shed some light on this please? Or do I simply run RANS approach with a different solver? Many thanks U

August 12, 2016, 11:26		#2
Tobi Super Moderator Tobias Holzmann Join Date: Oct 2010 Location: Bad Wörishofen Posts: 2,711 Blog Entries: 6 Rep Power: 52	Unsteady means that you solve in time (you are interested of the time evaluation). Therefore you should use PIMPLE or PISO solver. In the newer versions there is only the xxxPimpleFoam available that can operate in PISO mode too. A xxxSimpleFoam solver is normaly solving for steady-state and hence we have no time derivative that we take into account. If you don't know if a solver solves for a steady or unsteady problem. Check the equations in the source code and the fvSchemes for ddt and/or d2dt. __________________ Keep foaming, Tobias Holzmann

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