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Display regions central linear and upwind for gamma scheme

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Old   May 12, 2008, 13:26
Default Hi, has anyone a hint, how
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Fabian Braennstroem
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Hi,

has anyone a hint, how to display regions of central differencing and upwind scheme when using gamma (and filteredLinear)? I am having trouble to understand the implementation and would like to postprocess the use of the schemes...

Fabian
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Old   May 13, 2008, 05:33
Default Not a bad idea, but I don't th
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Eugene de Villiers
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Not a bad idea, but I don't think anyone has ever done this - at least I haven't seen any pictures to this effect.

Your first problem is that the discretization is defined for the faces of the mesh, not the cells, so you wouldn't be able to look at the raw results in a post-processor.
Secondly, the interpolation schemes do not have references to the database within their scope, so you can't access registered fields without major effort.

Should you have a solution for this, I would simply proceed to calculate the limiter for each face using the existing schemes outside of the solution loop and then check the value of the limiter to determine how much blending is being used. You would require some understanding of how the limiters are constructed and their method parameters are defined, so I wouldn't consider this a simple exercise.
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Old   May 14, 2008, 08:42
Default Thanks. I just tried to insert
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Fabian Braennstroem
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Thanks. I just tried to insert a simple 'Info' statement into Gamma and filteredLinear files writing out phict and the limiter.
I understand the postprocessing problems, but would'nt it be possible to average the limiter for each cell and write those values inside of the interpolation schemes!?

Fabian
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Old   May 28, 2008, 03:49
Default One way to calculate the limit
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Fabian Braennstroem
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One way to calculate the limiter is to collect the neighbouring values and calculate the limter by hand, but how is this done for an arbitrary cell. What are in these cases the upwind and downwind cells?

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