# multilayer porous

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 February 7, 2012, 07:52 multilayer porous #1 Senior Member   Shashwat Join Date: Nov 2011 Posts: 107 Rep Power: 8 Dear friend my problem is fluid flow through multiple co axial layers which has different porosity. Mr Glenn Horrocks suggested me that "Rather than specifying this as different sub domains with different permiabilities it might be better to define the porosity and permeability as a function of location and use a single sub domain with variable porosity and permeability". my questions are: 1. shall I need to create 5 ( for example) layers of different thickness in the design modeler? for example: 5 parts , 5 bodies 2. if not what to do in the design modeler? 3. Suppose if I have multiple layers more than 10 with different thickness , what shall I do? 5.If I create single solid in the design modeler, how to setup multiple layers in the solid as a different thickness and different porocity?. 6. As mentioned Mr Glen, How to define the porosity and permeability as a function of location and use a single sub domain with variable porosity and permeability? Please give one example. I am cracking my head Please help me Thanks in advance Shashwat

 February 7, 2012, 17:30 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,096 Rep Power: 109 No, one body which contains all the porous regions. Use a CEL function to vary the porosity and perm. Your question is how to define the CEL function - and as I said on the other post have a look at the CFX tutorials, especially the free surface flow over a bump one as that has a CEL function to set up the inlet condition. If you are cracking your head then get a band-aid.

February 8, 2012, 08:58
#3
Senior Member

Shashwat
Join Date: Nov 2011
Posts: 107
Rep Power: 8
Hi
Mr Glenn

In my porous case, if I create for example
insert>domain>porous

a window pop up. I set the porous domain then it asks porosity .Suppose I entered porosity as you mentioned as CEL expression for the layer 1.

How to set porosity of the second layer in the same domain?

Thank you

Regards

Shashwat
Attached Images
 1.jpg (48.9 KB, 7 views) 2.jpg (45.7 KB, 5 views)

February 8, 2012, 09:09
#4
Senior Member

Shashwat
Join Date: Nov 2011
Posts: 107
Rep Power: 8
Mr Glenn

Please find the attached print screen

Is it correct?
If I copy the domain , I have warning

"In Analysis 'Flow Analysis 1': The same location has been specified for more than one domain."

Please rectify my fault

Thank you

Regards

Shashwat
Attached Images
 3.jpg (58.8 KB, 4 views)

 February 8, 2012, 11:54 #5 Senior Member   Shashwat Join Date: Nov 2011 Posts: 107 Rep Power: 8 hi Let me explain my problem again 1.I have created cylindrical fluid part and on which I have created cylindrical solid part in design modeler ( 2 parts , 2 bodies) and I select two bodies and I did Form new part. 2.I did CFX mesh 3. in cfx pre I found two parts. next I create a fluid domain inner core. Next I tried to create porous domain for the outer portion.if I set this domain as porous I suppose to give porosity and permeability . But my outer core consists of multiple layers and different porocity. Dear Mr Glen I completed the tutorial "free surface flow over a bump"as you mentioned in the previous post. I am struggling to correlate it to my problem . Can you please give some example or tips which I can proceed further Thank you Regards Shashwat

 February 8, 2012, 17:58 #6 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,096 Rep Power: 109 Have a look at how the boundary conditions are set up with CEL expressions. This is one way to make a parameter vary over a boundary. This technique can also be used to set volume parameters like porosity and permeability.

 February 9, 2012, 20:19 #7 Senior Member   Shashwat Join Date: Nov 2011 Posts: 107 Rep Power: 8 Dear Mr Glenn I have doubt in the tutorial "free surface flow over a bump"as you mentioned in the previous post. I believe that the total height of the column ( water +free surface) is 0.1 m Note: The total height was not given .But the height of the bump was given 0.03m. While writing CEL expression for the upstream free surface height they have taken taken free surface height as 0.069m my question is why they didn't take free surface height as 0.07m? or is the total height 0.099m? Thank you shashwat

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