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Nirmal Kumar Pathak October 26, 2005 07:01

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.

Richard October 26, 2005 07:19

Re: Modeling porous media flow in prostar
 
Isn't the porosity only a factor for transient simulations? Are you running transient?

Nirmal Kumar Pathak October 26, 2005 07:23

Re: Modeling porous media flow in prostar
 
Ya ,some body had told me this. but then how to go for steady state problems.

Richard October 26, 2005 08:47

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?

Nirmal kumar pathak October 27, 2005 04:30

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???

Richard October 27, 2005 08:02

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).

Nirmal Kumar Pathak October 28, 2005 00:35

Re: Modeling porous media flow in prostar
 
hello Richard,

Thanks a lot for your replies.

limingtiger October 30, 2005 03:19

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

Mahesh Masurkar November 23, 2005 08:18

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


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