need for an unsteady implicit solver suitable for large timestep

dinonettis · May 24, 2010, 15:11

Dear all,

at the moment I'm facing the simulation of a flow around a sphere. The Reynolds is very low (27), therefore pressure and velocity are steady.
However the next step consists in performing a simulation in which the temperature at the inlet is linearly changing in time. Therefore I have to use a transient solver.
Due to the fact that the flow is steady (no risk of changing the physics of the flow) and due to the huge amount of time I have to simulate, I think the best solution is a very large time step. That's not possible with icofoam since it will take approximately 400 days to obtain the solution!!!! But I hope my PhD will end up by that time

))
Somebody knows an alternative solver able to do that?!?!?
Thanks in advance,

Dino

dinonettis · May 25, 2010, 13:40

I already tried pimpleFoam, but it seems to be not appropriate since starting from a converged solution, in terms of pressure and velocity, and using a Co=2 the pressure residuals are fixed to 0.8!!!!
Any suggestion is well accepted!!

stawrogin · May 26, 2010, 07:57

Hi Dino,

maybe this thread helps:

http://www.cfd-online.com/Forums/ope...ime-steps.html

stawrogin

May 24, 2010, 15:11	need for an unsteady implicit solver suitable for large timestep	#1
dinonettis Member Leonardo Nettis Join Date: Mar 2009 Posts: 72 Rep Power: 17	Dear all, at the moment I'm facing the simulation of a flow around a sphere. The Reynolds is very low (27), therefore pressure and velocity are steady. However the next step consists in performing a simulation in which the temperature at the inlet is linearly changing in time. Therefore I have to use a transient solver. Due to the fact that the flow is steady (no risk of changing the physics of the flow) and due to the huge amount of time I have to simulate, I think the best solution is a very large time step. That's not possible with icofoam since it will take approximately 400 days to obtain the solution!!!! But I hope my PhD will end up by that time )) Somebody knows an alternative solver able to do that?!?!? Thanks in advance, Dino

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May 25, 2010, 13:40		#2
dinonettis Member Leonardo Nettis Join Date: Mar 2009 Posts: 72 Rep Power: 17	I already tried pimpleFoam, but it seems to be not appropriate since starting from a converged solution, in terms of pressure and velocity, and using a Co=2 the pressure residuals are fixed to 0.8!!!! Any suggestion is well accepted!!

May 26, 2010, 07:57		#3
stawrogin Member Join Date: Nov 2009 Posts: 36 Rep Power: 17	Hi Dino, maybe this thread helps: http://www.cfd-online.com/Forums/ope...ime-steps.html stawrogin