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Impose transeint force

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Old   March 3, 2011, 17:52
Default Impose transeint force
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Henry Arrigo
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Hello,
How can I impose a sinusoidal force on a body. In the external force node there is no possibility to bind a Field function. What s your suggestions please?

Thank you.

Last edited by Henry Arrigo; March 3, 2011 at 18:51.
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Old   March 3, 2011, 17:54
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any one can help me please?
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Old   March 4, 2011, 00:29
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If the field function is not available you need to write a macro.

A simple strategy is to record a macro where you set a value for the external force with a numeric value.

Use this macro as a initial construct and instead of the numeric value replace it with your function.
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Old   March 4, 2011, 10:07
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thank you
this is not gonna work since I need to impose a continuous force while this case would result in a discrete one. more over I want to come up with solution in a single run.
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Old   March 7, 2011, 00:28
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Hi,

As long as you are using CFD for your simulation you cannot apply continuous force.

Whatever you do, even if you manage to get your BCs via a field function you will be using a finite time step and hence your profile will always be implemented in discrete time steps and not in a continuous fashion as you have envisioned.

So the only remedy to the above problem is to use a smaller time step while applying the acceleration profile.

Hope you got that
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Old   March 7, 2011, 10:01
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Henry Arrigo
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Hi,
Thank you Alastormoody.
Did you mean applying acceleration to the fluid field? Did I get it right.

In the wall node and in the Physics Conditions sub-node, there is an option which is named Tangential Velocity Specification. It has this possibility to use a field function as a vector field. Have you ever use that? I guess that could be a remedy too...

Thanks.
Henry
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