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internal variable porosity permeability
Posted Aug 2, 2016, 12:16 a.m. EDT Fluid & Heat Version 5.2a 2 Replies
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I, beginner to COMSOL, am using poroelastic model in COMSOL fully saturated porous medium, all the pores are filled with fluid. Hence porosity is equal to the ratio of volume of the fluid to the total volume. The solid deformation will affect porosity an permeability.
When the volumetric strain changes occur in the model, the porosity must change accordingly. But in COMSOL poroelastic model, the variable porosity seems to be constant through out analysis.
Porosity seems appear only in storage coefficient but not inside any differential term.
How could i input this into model ?? Would anyone has any idea ?? I am sure this is already implemented in Abaqus, but i am wondering how to do it in COMSOL ?
I desperately need to model porosity as vol. strain dependent as permeability in soft tissue is porosity/strain dependent.
Thank you in advance !
When the volumetric strain changes occur in the model, the porosity must change accordingly. But in COMSOL poroelastic model, the variable porosity seems to be constant through out analysis.
Porosity seems appear only in storage coefficient but not inside any differential term.
How could i input this into model ?? Would anyone has any idea ?? I am sure this is already implemented in Abaqus, but i am wondering how to do it in COMSOL ?
I desperately need to model porosity as vol. strain dependent as permeability in soft tissue is porosity/strain dependent.
Thank you in advance !
2 Replies Last Post Aug 5, 2016, 6:30 a.m. EDT
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Posted:
8 years ago
I did some simple measurements to estimate the relationship between compression and porosity and then used some literature data to establish a relationship between permeability and porosity. Then I defined the material with porosity dependent on (x, y). I got stuck for a long time because I was not aware that the geometric coordinates are not available in the global variables, as the geometry only applies locally within the specific component. So define the porosity =f(x,y) as a local variable.
My problem was then that I really want a) partially saturated porous material (with air and water); and b) gravity drainage - and it seems that these require the CFD or sub-surface module, therefore have parked this activity pending further investment...
cheers
My problem was then that I really want a) partially saturated porous material (with air and water); and b) gravity drainage - and it seems that these require the CFD or sub-surface module, therefore have parked this activity pending further investment...
cheers
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Posted:
8 years ago
My model is simple triaxial experiment. I defined the porosity change depends on the volumetric strain( poro.evol) in variables as picture showed. The volumetric strain changes with time. The expression is the function of the volumetric strain( poro.evol), but the porosity is still constant and didn’t change as the expression. Is there some problem about my expression?
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