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A general question on solving NS equations with an ALE description

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Old   July 22, 2011, 04:26
Default A general question on solving NS equations with an ALE description
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Hi,

Just a general question about the ALE approach. In the ALE approach you have both the mesh velocity and the flow velocity and therefore an extra unknown has been added to the NS equations. Is an extra equation needed to solve the equations now and what would that equation be?

Thanks,

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Old   July 23, 2011, 17:08
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The mesh velocities (magnitude and direction) are input to the fluid motion equations. You have to prescribe those velocities. You can specify values appropriate for your problem or
use appropriate physics (boundary motion, acceleration, ???) to specify an equation of motion for the mesh points.
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Old   July 23, 2011, 17:54
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Thanks very much.

I have seen a few relationships and am confused by them a little. What I was thinking about was to use this relationship: dv/dL = constant, where L is the cell length.

But I'm not sure maybe I should use:
dv/dt = constant,

Or dL/dt = v(t=n) - v(t=n+1),

Or that the cells are increased or decreased in size by the same amount such that dL/dt = constant i.e. v = constant.

I would appreciate you help.

Thanks,

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Old   August 7, 2011, 06:18
Default Initial conditions for an unsteady flow problem in 1D
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I was going to post a new question and accidentally wrote here. Please ignore this...

Last edited by Hooman; August 7, 2011 at 06:19. Reason: wrong place
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Old   September 5, 2011, 18:47
Default unsteady flow - issue with for loop
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I was going to post a new question and accidentally wrote here. Please ignore this...

Last edited by Hooman; September 5, 2011 at 19:12.
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