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CFX Transient Initialization

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Old   June 16, 2016, 17:17
Default CFX Transient Initialization
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Ferruccio Rossi
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Hi,

I am running a two-ways FSI of a wing with CFX at a speed of 110 m/s. I found sources online where they explained that Initialization is the process to assign a value to unspecified solution fields. I assume it means that every cell in the domain will have the initial conditions specified in the Initialization menu. Is this correct?

For my case, as you can see from the picture, I already specified all the initial conditions (inlet, outlet, farfield,..) for every part of the fluid domain. Do I still need Initialization? Or should I leave the velocities components as 0?

I tried to run simulations with and without setting an Initialization value, and the results are pretty close. Can someone explain me in detail what the "Initialization" window does please?


Thank you.
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Old   June 17, 2016, 10:31
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Initialisation is intended to define a "known" start state in one hand.
On the other defining an initialisation close to the expected solution makes it easier for the solver to converge and also it can help you in the case your simulation wouldn't start or crash very fast. When you have too high gradients at the bginning it might be that the solver will not find the correct solution and simply diverge.

So in your case, atlhough the jump from 0 m/s to 11 m/s is quite big you seem to be lucky and the solver is able to find a converged solution.
As the (correct) initialisation only reduces the time until the solver has found the correct solution the end result will not differ significantly.
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