User-Defined Potential Force in multiphase flow

cen · January 11, 2018, 09:44

Hello everyone. I have a question about the User-Defined Potential Force: Flow in a Porous Medium in the user guide.

the capillary pressure as user defined potential can be set according to

Pc=-G0*C/Alpha ^m

but C is related to Pc, which is

C=Alpha /Gmma * dPc/d Alpha

so how can I set the user define field function in this case?

thanks!!

Cen

fluid23 · January 15, 2018, 15:11

It would be helpful if you could specify exactly where you are seeing this in the user guide...

(i.e. user guide > modeling physics > etc...)

That being said, you are missing some critical piece of information. if C is determined from the gradient of dPc/d alpha, then your system of equations isn't closed and you cannot solve for C. I will try to help you sort this out if you can provide a little more info.

cen · January 16, 2018, 03:08

Quote:

Originally Posted by fluid23

It would be helpful if you could specify exactly where you are seeing this in the user guide...

(i.e. user guide > modeling physics > etc...)

That being said, you are missing some critical piece of information. if C is determined from the gradient of dPc/d alpha, then your system of equations isn't closed and you cannot solve for C. I will try to help you sort this out if you can provide a little more info.

thanks for you Reply.

I saw this in:

user guide > modeling physics > modeling multiphase flow > using the eulerian multiphase model > modeling user-defined potential forces > user-defined potential force: flow in a porous medium

fluid23 · January 16, 2018, 13:41

Ok... I have reviewed what is available in the help documentation. It does appear that you are referencing an old version of the files since I found this under:

Star CCM+ > Simulating Physics > Modeling Multiphase Flow > Using the Eulerian Multiphase Model > Modeling User-Defined Potential Forces

That being said, I would check the most current help files on Steve Portal just in case there is something new that you don't see. Just glancing over what is shown, it looks to me like the user potential volume fraction derivative (dPc/d alpha) is a user input. Not being all that familiar with this particular model, I would speculate that your specific problem and materials will dictate what that derivative is.

Good Luck.

January 11, 2018, 09:44	User-Defined Potential Force in multiphase flow	#1
cen New Member Join Date: Oct 2017 Posts: 10 Rep Power: 8	Hello everyone. I have a question about the User-Defined Potential Force: Flow in a Porous Medium in the user guide. the capillary pressure as user defined potential can be set according to Pc=-G0C/Alpha ^m but C is related to Pc, which is C=Alpha /Gmma dPc/d Alpha so how can I set the user define field function in this case? thanks!! Cen

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January 15, 2018, 15:11		#2
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 17	It would be helpful if you could specify exactly where you are seeing this in the user guide... (i.e. user guide > modeling physics > etc...) That being said, you are missing some critical piece of information. if C is determined from the gradient of dPc/d alpha, then your system of equations isn't closed and you cannot solve for C. I will try to help you sort this out if you can provide a little more info.

January 16, 2018, 13:41		#4
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 17	Ok... I have reviewed what is available in the help documentation. It does appear that you are referencing an old version of the files since I found this under: Star CCM+ > Simulating Physics > Modeling Multiphase Flow > Using the Eulerian Multiphase Model > Modeling User-Defined Potential Forces That being said, I would check the most current help files on Steve Portal just in case there is something new that you don't see. Just glancing over what is shown, it looks to me like the user potential volume fraction derivative (dPc/d alpha) is a user input. Not being all that familiar with this particular model, I would speculate that your specific problem and materials will dictate what that derivative is. Good Luck.