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CFX solver interpolation

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Old   July 1, 2018, 10:47
Default CFX solver interpolation
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Fahd Mohamed Elabd
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Hi guys,

I used user defined remeshing through junction box routines. CFX solver interrupt the calculation at each time step, then replace the mesh file with new one and interpolate the result of old mesh into the new mesh.

which type of interpolation CFX uses.
do I have access to change it or not and how?
Does interpolation scheme affect results?

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-Fahd
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Old   July 1, 2018, 18:50
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Glenn Horrocks
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It is almost certainly linear interpolation. I have not found a reference to justify that but I would imagine higher order interpolation would cause more trouble than it is worth due to unphysical overshoots.

I do not think you have access to change the interpolation done by CFX. If you want to change the way this is done you can write your own initial condition in user fortran and use what ever interpolation scheme you like.

Yes, interpolation scheme will affect results. Getting an interpolation scheme which is conservative is challenging. Also getting one which accurately keeps rapid changes in variables is also challenging. Getting a scheme which does both is just about impossible.
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Old   August 3, 2018, 01:53
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Lance
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The expert parameter
Code:
    interp second order data = t
will change the interpolation to second order. But beware, the .res files will become bigger.
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Old   August 3, 2018, 06:25
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Glenn Horrocks
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I did not know that, thanks!

But be aware that higher order functions are prone to gross overshoots. Caveat emptor!
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