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-   -   Defining porous zone in fluent (http://www.cfd-online.com/Forums/fluent/125212-defining-porous-zone-fluent.html)

 dreamz October 21, 2013 12:26

Defining porous zone in fluent

I want to model a problem in which a rectangular solid which is actually a tissue present in human body. Blood flows through one of the faces and exits from the opposite one. The top face has predefined temperature. In cell-zone conditions in fluent, the option of porous zone is given only for fluid. Now, default material is air. In my case fluid flowing is blood. But blood cannot be porous. So, I need to define the whole rectangular solid as porous. How should I do it?

 silverra1n October 21, 2013 13:48

porous

hi!
You cannot do porous media as a solid. Because if you want do solution as a porous media you must specify it fluid. Because it will act like solid after your definition.

 A CFD free user October 21, 2013 15:08

@Dreamz
Based on what you mentioned, I can't see what's the necessity to define your model as porous! What you described is a typical problem. Please make it more clear, if you would.

 Kokemoor October 21, 2013 18:12

Porous media is a fluid cell zone condition. It doesn't mean that the fluid itself is porous, but instead that the fluid is flowing through a porous media whose characteristics you will describe through physical constants.

 dreamz October 21, 2013 23:03

@ A CFD free user:

The tissue in human body is porous. Hence I need to define this as porous medium

 dreamz October 21, 2013 23:08

@Kokemoor:
okay I got it. Now, through the tissue blood is flowing. So shall i change the material air to blood?

Also, in cell zone conditions when we activate porous zone, it asks for porosity value. So here, I should give the porosity value of the solid. Am I correct? (because blood won't have porosity values)

 Vidyanand Kesti October 22, 2013 00:20

Tissue can be defined as porous zone in cell zone condition; you can calculate the porous boundary condition either by Darcy or by testing. Assign the direction -1 and direction-2 as same value in porous zone condition

if you can try with porous jump as well in boundary condition.

 A CFD free user October 22, 2013 07:55

@ Dreamz
Yes, as the other guys mentioned, a porous zone is a fluid cell zone not a solid zone. To define a porous zone, you need to have at least two important parameters, viscous resistance which is in fact the inverse of permeability and porosity. There are other options as well, but these two are more common. You can also define your media as isotropic or anisotropic depending on your problem. One more thing, there is a relationship between porosity and tortuosity, you can extract the porosity from it.
Hope it helps

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