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Porous Medium-entering D, F coefficients to code

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Old   January 4, 2019, 09:36
Default Porous Medium-entering D, F coefficients to code
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Sama
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I have calculated F and d coefficients for Darcy Forchheimer equation for my porous media and I have two scalars. I saw in code F and D should be entered like vectors:

type DarcyForchheimer;

d (500000 -1000 -1000);
f (0 0 0);

I dont know what those two -1000 mean and how I should calculate them!
I would appreciate it if any one could help me.
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Old   January 7, 2019, 04:24
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Hi,

The -1000 is a way to do multiplication. As only a positive number is valid, OpenFOAM uses a negative number as a multiplier. So your D values are equivalent to:

d (500000 500000000 500000000);

This way, you can force directionality of your porous region (i.e. a radiator that typically shows higher resistance in cross-flow directions than in flow direction).

Regards,
Tom
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Old   January 7, 2019, 08:46
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Thank you so much Tom,
In cases that we are sure porous media is homogeneous and air permeability/resistance in all directions are same, should we enter (500000 50000 50000)?
Thank you,
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Old   January 7, 2019, 09:46
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Yes, or alternatively

(500000 -1 -1)
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