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Porous Viscous Coefficient

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Old   June 21, 2020, 06:27
Post Porous Viscous Coefficient
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Yogesh Nalam
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Hello All,

I was trying to compute porous coefficients and I have a negative value for my viscous coefficient. Is it possible to have negative values or what should be done in that case?

Thanks !!!
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Old   June 22, 2020, 08:38
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A negative resistance value doesn't make sense.

How are you computing the value?
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Old   June 24, 2020, 11:01
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I have plotted Pressure Drop per unit length against velocity (Values from CFD and not experiments) and then just fitted a quadratic trend line to get coefficients.
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Old   June 24, 2020, 12:03
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This could just be a figment of your curve fit. The values don't make physical sense as negative, but should work out numerically. Just make sure to set up a report to make sure that the velocity/pressure drop line up with your expected curve.
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Old   June 25, 2020, 03:21
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That is true. It did not give any errors numerically. Okay, I will have to check the pressure drop reports then.

Thanks a lot.
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Old   Yesterday, 07:24
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Quote:
Originally Posted by nalamyogesh View Post
That is true. It did not give any errors numerically. Okay, I will have to check the pressure drop reports then.

Thanks a lot.
Some times -ve value comes due to curve fitting, try to remove points from the input data which is looking suspicious and try fitting the curve again. If possible share the curve.
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