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Question about accelerating the convergence by changing the timestep

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Old   September 15, 2012, 17:55
Question Question about accelerating the convergence by changing the timestep
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Meimei Wang
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Hi,

We often change the time step in the middle of the simulation running to accelerate the convergence. For example, according to the FAQ of this forum, we can set the time step to local time step with factor of 5 at the beginning. Then when the RMS does not decrease anymore, we can change the time step to let it continue to decrease.

But how do we know what time step should I change to?
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Old   September 16, 2012, 07:50
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The CFX documentation describes setting the time step - a good starting point is the fluid residence time in the domain. But note this is only a guide - if the simulation is converging well a larger time step is possible, if convergnce is difficult a smalle rtiem step will be required.
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