# porous media flow

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 February 21, 2006, 08:30 porous media flow #1 Siraj Guest   Posts: n/a HI,my project involves porous media flow. i have the value of pressure drop across the length of the porous medium.and the velocity of fluid at entry to the pipe is also known.the porous medium is quite a distance away from the entry.i need to know how the values of alpha(a) and beta(b) can be calculated from the expression dp/L=(a*v^2+b*v).what velocity should i substitute in this relation.the STAR-CD methodology says its the characteristic velocity.how do i get that.kindly help.thanks all!!! and the flow is orthotropic

 February 21, 2006, 08:57 Re: porous media flow #2 Mork Guest   Posts: n/a You can use the average velocity across a section of your porous region. to calculate alpha and beta you need two data pairs of pressure drop as a fct. of velocity.

 February 21, 2006, 11:35 Re: porous media flow #3 Siraj Guest   Posts: n/a thanx Mork i'll plug in the average velocity as u suggested.can u please elaborate on what u meant by saying "two data pairs of pr.drop as a factor of velocity".

 February 22, 2006, 04:55 Re: porous media flow #4 Mork Guest   Posts: n/a You got an equation with two variables. You know the pressure drop for one flow rate value (and therefore for one velocity). If you know the pressure drop for a second velocity value, you can determine alpha and beta without problem. Hope that helps!

 February 24, 2006, 22:24 Re: porous media flow #5 Siraj Guest   Posts: n/a yes i got that!!thanks.Regards!!