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Convergence problems using extreme coefficient values like 1e-16 with porous jump

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Old   April 2, 2013, 16:16
Default Convergence problems using extreme coefficient values like 1e-16 with porous jump
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Recep Kaya
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Hi fellow CFD users,

I want to model a cylindirical membrane(plenty of membranes) in a cross flow condition, and when I use permemability and C2 coefficients like 2e-16 for face permeability and 3e+12 for C2, problem diverges. I have to use this coefficients because membranes that I want to model, has kind of 0.0001m/s velocity at 100000Pa values. I am sure these coefficients are the reason behind the divergence.

How can I solve this divergence problem ?

Thanks
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Old   April 3, 2013, 11:07
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OJ
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As you guessed it, are you sure about these coefficients? How did you arrive at these values?

OJ
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Old   April 4, 2013, 10:23
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hi oj

I arrive this values by plotting xy curve from my experimental data velocity and pressure drop, from the xy polynomial trendline excel generated the y=Ax2+Bx equation that I used to find C2 and alfa permeability coeffitions. I double checked everything that I do in excel. I am sure these coefficients is right. Because these coefficients belongs to a membrane that 0.5micrometer or even lower pore sizes. It has very low permeability compairing to normal filters.
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