Porosity changes
Hello Foamers.
I want to model a flow with a porous zone which works well using rhoPorousSimpleFoam in OF 2.1.x. I want to examine the effect of porosity on the answers. But change does not change the porosity of the porousZones.H in the constant folder. I think it is not used at all porosities. Who can help me? Best regards. vahid 
dear vahid
specify your problem with much more clarification and insert one simple test case 
Quote:
I am working a new solver for combustion in porous media. i work on two solver reactingFoam and rhoPorousReactnhFoam for simolation combustion in porous media. i think the solver rhoPorousMRFSimpleFoam only the initial porosity(porosity=1) and dont used amount of porosity(for example porosity=0.781 define in porousZones.H in the constant folder). i thenk the porosity is private on class porousZone and the solver dont used the amount of porosity. the solver used amount of default in porousZones.C !!!! 
which version of OpenFOAM, do you use?

openfoam2.1.1
can you help me? 
Code:
1 
hellow nimasam
my model is 1 ( porosity { coordinateSystem { e1 (0.70710678 0.70710678 0); e2 (0 0 1); } porosity 0.8; Darcy { d d [0 2 0 0 0 0 0] (5e7 1000 1000); f f [0 1 0 0 0 0 0] (0 0 0); } thermalModel { type none; //fixedTemperature; // fixedTemperature coefficients T 350;//1350; } } ) 
dear vahid
you are right, it seems it is a bug, so report it as a bug 
hello nimasam
i dont know!!! i have to work on combustion in porous mdeia. I have hard problems in modeling!! 
maybe you want to look in source code, where it uses porosity,
However combustion is a complex phenomena, you need to be expert in existing solvers then try to implement new code, so 1try to understand existing test case, 2find nearer solvers to your case 3read source codes, find out what each part does 
hello nimasam
I have searched the reference code. porous media is modeled attenuting the time derivative and by adding sink term to the navier stokes eqn. sorce term is viscous and inertial lose. but my momentum eqn should be porosity multiplied the other terms in porous zone in adding to the above. How do you know that? Best regards. vahid 
you should learn how to program in OpenFOAM, maybe reading user guide and programmer guide and reading source codes, help you to get familiar with coding at OpenFOAM, if you want more, you can connect me ;)

hello nimasam
I'm willing to be in contact with you more. thanx alot give me email adress :) of course i have read user guide ago. Best regards. vahid 
here, you can find contact info:
http://www.cfdonline.com/Forums/members/nimasam.html 
porous value
hellow
dear vahid how can i chenge my porous value in openfoam 2.0.1? can you explain me how do you got that value of alpha,beta ,a,b? thanks alot Quote:

Dear hesam
I think is betterd enter the amount of porosity in the DarcyForchheimer coefficient. what are alpha, beta,a,b? 
would you explain me what are the darcy's coefficient?
i saw some where there are alpha,beta,a,b that calculate the porosity when the material isn't isotoropic !!! thank you Quote:

dear hesam
you can check files in "/opt/openfoam211/src/finiteVolume/cfdTools/general/porousMedia" or do research on the references about the porous medium equation. best regards 
dear vahid i checked the location that you mentioned...
these are the coefficient that i said: a = 9.367 b = 1.029E7 alphax = 0.5 * a * density [kg/m^4] betax = viscocity * b [kg/m^3s] d= beta/viscocity [1/m^2] f=2*alpha/density [1/m] alphay=1e6 betay=1e6 alphaz=1e6 betaz=1e6 viscocity=1.663e5 kg/ms density=0.61935 at Inlet coordinateSystem { e1 (1 0 0); e2 (0 0 1); } Darcy { d d [0 2 0 0 0 0 0] (1.029e7 (6.01e10??) (6.01e10??)); f f [0 1 0 0 0 0 0] (18.367 (?) (?)); these are for ceramics, i want to know from where i can obtain them?? thanks alot for your help vahid Quote:

dear hesam
d and f are DarcyForchheimer coefficient and has been explained in ...cfdTools/general/porousMedia/porousZone.H, or you can read "porous media in openfoam.pdf" in internet. but if you have new equations you can define them. you can do this with reading user guide, programmer guide and reading source codes. best regards 
All times are GMT 4. The time now is 08:05. 