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-   -   unsteady simulation (http://www.cfd-online.com/Forums/fluent/84643-unsteady-simulation.html)

hamid1 February 4, 2011 09:43

unsteady simulation
 
Hello guys

for unsteady simulation should one first have a converged solution in steady and then shift to unsteady or thats is not necessarily compulsory?

Amir February 4, 2011 10:55

Hi hamid,
it's not necessary to initialize unsteady problem with converged steady one.
but in some special cases like small perturbations and ... it helps you to have fewer iterations per time steps.

hamid1 February 4, 2011 11:41

thanks Amir,
but if I dont have a steady converged initialized solution does it mean that I cant rely on my unsteady simulation at the first few steps of time duration?

Amir February 4, 2011 13:47

your answer in unsteady simulation is reliable if and only if the residuals after each time step satisfy your convergence criteria. but as I said before , in some special cases if you have a good initialization data field , the convergence criteria may takes place in fewer iteration per time step . (this tip doesn't change the generality of the first sentence)

itsuetian@hotmail.com February 4, 2011 16:37

For unsteady simulation it is not mandatory to have converged solution in steady and then shift to unsteady simulation.You can start with unsteady simulation and can rely on that.I have worked on the unsteady simulation of flow arround cylinders and it gives reliable results.


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