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Gravity is not constant in my case

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Old   January 6, 2009, 08:48
Default Gravity is not constant in my case
  #1
bastien
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Hi,

I am trying to simulate a reservoir under variable acceleration (sloshing case). It is well known that it is equivalent to a variable gravity.

However in star-ccm++ I do not find how to made the gravity variable (user function).

Any idea?

Regards
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Old   January 6, 2009, 11:53
Default Re: Gravity is not constant in my case
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steve
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Hi,

Your best bet here is a java macro to update the value of gravity before each timestep.

To do this, record a macro of you setting the gravity and then taking a timestep. Afterwards open the .java file and wrap the commands in some sort of java for or do loop and then modify the gravity function as required.

Regards

Steve

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Old   January 6, 2009, 15:11
Default Re: Gravity is not constant in my case
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bastien
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Hi

Thank you it work like a charm

I need to track the altitude of the free surface, any means simpler then adding all the volume against the vertical and dividing by the length?

waterheight=sum(vof(x=cst,y=cst,z))/(length*volumebase)

Regards

Bastien
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Old   January 6, 2009, 17:18
Default Re: Gravity is not constant in my case
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steve
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Hi Bastien,

What about a field function

($VolumeFraction0>0.5)?$$Centroid[2]:-1e12

Then create a maximum report of this field function for where ever you are interested (plane section, fluid domain etc.).

Is this perhaps what you are after?

Steve

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Old   January 7, 2009, 13:39
Default Re: Gravity is not constant in my case
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bastien
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It works thank you.

Bastien
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Old   January 23, 2009, 00:41
Default Re: Gravity is not constant in my case
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mahi
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Hi,

Can you send me the macro for the variable gravity case? I am also working on a similar case.
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