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Mass flow sink (source point) --Absolute pressure keeps dropping

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Old   November 18, 2013, 15:35
Default Mass flow sink (source point) --Absolute pressure keeps dropping
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Hi, there,

I am using source point to simulate the mass flow sink on the wall.
I set the option of the continuity as "Total Fluid Mass Source", the "Total Source" set to a negative value.

The problem is that the absolute pressure at the source point keep dropping to non-physical value, which causes the CFD unstable, and can't converge.

Anyone knows why? And what should I change the source point setup?

I have used "pressure coefficient". Since it is mass flow sink, I have a positive number there.

If I turn on the heat transfer, what else should I pay attention to?

Thanks in advance.

Nan
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Old   November 18, 2013, 17:47
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The answer is pretty obvious - a mass sink point is not physically possible (this side of the nearest black hole anyway), so of course it will lead to non-physical results.

I would replace the point with a source volume and then you can spread the mass sink out over a larger volume and reduce the pressure spike and hopefully get convergence.
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Old   November 18, 2013, 23:59
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Glenn,

Thanks for the reply. I did quick search, can't find the way to create volume source. If you can give me some instructions or point me to some references. I really appreciate it. I am using cfx 14.0 now.

Thanks again.

Nan
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Old   November 19, 2013, 00:21
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It is very simple - you just make a mesh volume and assign a volume source to it. An example is the Heat transfer in a heating coil tutorial. (Actually I see in V14.5 that the heating coil example has been changed to use the electric potential model rather than a heat source)
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