Modeling porous media flow in prostar
 

Hello,

I am working on some problem of porous media flow in prostar(starcd). To check as a trial, I changed the values of porosity in model,but i am not getting any effect. On setting the value of porosity as zero,it should behave as a solid. but it is not showing any changes in results. kindly help me.

Re: Modeling porous media flow in prostar
 

Isn't the porosity only a factor for transient simulations? Are you running transient?

Re: Modeling porous media flow in prostar
 

Ya ,some body had told me this. but then how to go for steady state problems.

Re: Modeling porous media flow in prostar
 

In steady-state, all you are doing with a porous medium is specifying pressure-drop as a function of fluid velocity. I don't know that you could stably model a solid like this. Why do you need to?

Re: Modeling porous media flow in prostar
 

I am modeling a shell and tube heat exchanger for getting shell side flow distribution for a steady state problem. The domain of U-tubes is being modeled as porous media .The value of porosity, i have used is 0.68(hand calculated as ratio of open vol. to total vol.)Just to check,I was trying to get the variation of results(vel. contours) with varying values of porosities(within a range of 0 to 1) keeping all porous resistance coefficient values same.According to my perception,When the value of porosity is 0.0,the domain which has been defined as porous media should behave as a solid and no flow should be able to pass across it.No change in results have been observed for different porosity values. HOW SHOULD I PROCEED???

Re: Modeling porous media flow in prostar
 

The porosity will have no effect on the calculation as it is steady-state, which is why you get the behaviour you have found. It's not a bug - see the methodology manual. The only useful validation you can make of your porous medium is to check that pressure drop vs. flow rate is what you expect it to be (given the coefficients you have supplied).

Re: Modeling porous media flow in prostar
 

hello Richard,

Thanks a lot for your replies.

Re: Modeling porous media flow in prostar
 

what's the problems about my following command? i want to define the fluid with the porosity 0.5, but the result is wrong. ctab,4,fluid,7,0.5,4,1,1,1,0,off,0,light CELL TABLE NUMBER 4 IS FLUI

NAME = soil

COLOR INDEX = 7 POROSITY INDEX = 0

MATERIAL NUMBER = 4 SPIN INDEX = 1

GROUP NUMBER = 1 LIGHTING MATERIAL = 1

RADIATION = OFF

CONDUCTION THICKNESS = 0.000000

INITIAL FREE SURFACE MATERIAL IS LIGHT

MESH*> ctname,4,soil NAME OF CELL TABLE 4 IS soil

Re: Modeling porous media flow in prostar
 

This is the porosity index no. which is an integer,say 1.

You should define the porosity in the Thermophysical models-->porosity-->porosity index #1.

Mahesh