momentum loss equation porous media

pato · March 17, 2012, 17:50

Hi,
i am modelating flow through a porous media as a simplification of a perforated difusser.
In order to obtain the same velocity profile as i did in the real perforated diffuser, i am taking different values for permeability coefficient and resistance loss coeffcient.
As far as i know, both of them define the mometum loss in the porous domain(both terms take part in the momentum loss equation), and hence the pressure drop.
would it actually be the same just changing one of these two parameters? could i get the same results by just changing one of them with a wide range of values?
is there actually any diffrenece between both of them? (i am refering to the effects on the porous media)

could anyone help me please?

evcelica · March 21, 2012, 18:28

permeability is the linear part of the loss model. loss coefficient is the quadratic part. you can use either one or both, depending on the characteristics of your diffuser. Solver theory guide will give you the exact formula for each I cant remember of the top of my head, or can I.....

DeltaP = -(Viscosity * Velocity / K.perm) - (Density*Loss.Coefficient*Velocity^2)
units will be Pa/m

March 17, 2012, 17:50	momentum loss equation porous media	#1
pato Member albert Join Date: Jan 2012 Posts: 31 Rep Power: 14	Hi, i am modelating flow through a porous media as a simplification of a perforated difusser. In order to obtain the same velocity profile as i did in the real perforated diffuser, i am taking different values for permeability coefficient and resistance loss coeffcient. As far as i know, both of them define the mometum loss in the porous domain(both terms take part in the momentum loss equation), and hence the pressure drop. would it actually be the same just changing one of these two parameters? could i get the same results by just changing one of them with a wide range of values? is there actually any diffrenece between both of them? (i am refering to the effects on the porous media) could anyone help me please?

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March 21, 2012, 18:28		#2
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,167 Rep Power: 23	permeability is the linear part of the loss model. loss coefficient is the quadratic part. you can use either one or both, depending on the characteristics of your diffuser. Solver theory guide will give you the exact formula for each I cant remember of the top of my head, or can I..... DeltaP = -(Viscosity * Velocity / K.perm) - (DensityLoss.CoefficientVelocity^2) units will be Pa/m