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Old   April 16, 2010, 12:28
Default rotating domain
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Ciro Cannavacciuolo
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Hi to everybody,
I'm simulating a multifase rotating domain in wich the axis of rotation doesn't match with one of the global ones.

So, I defined a local Coord and specified one of them as rotation axis.

The simulation doesn't work because:

This simulation involves a gravity vector which is not aligned with the rotation axis. Because the solver currently interprets the gravity vector as being in the relative frame, the gravity vector must be made a function of time so that it is constant in the absolute frame (ie, counterrotating in the relative frame).

Could someone help me in order to undestand the problem?

I specify that I have experiences with multiphase simulation with rotating domain. I never had problems because the rotation axis was coincident with one of the global ones.

Thank you in advance
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Old   April 18, 2010, 07:42
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Glenn Horrocks
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Looks like you might have to define gravity as a body force yourself and make it a function which makes it point in the direction you want. Then you can do whatever you like to the gravity vector - but you will have to do the maths to make it point in the correct direction, including the rotating frames of reference stuff.
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Old   April 19, 2010, 10:52
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Ciro Cannavacciuolo
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Hi,
the rotating velocity is "omega". Vertical global axis is Z. So, in a stationary domain the gravity vector as theese components:

g_x=0
g_y=0
g_z=-g

Now, if I have to define a time function in order to have the g vector always alligned to Z axis, I think I have to made zero g_x and g_y defining expression such as

g_x(t)=g_y(t)=g*sin(omega*t).

Is it correct?
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