CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT > Fluent UDF and Scheme Programming

UDF-Mass Fraction

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 26, 2018, 13:41
Default UDF-Mass Fraction
  #1
New Member
 
Sherif
Join Date: May 2012
Posts: 5
Rep Power: 10
Gomaa is on a distinguished road
Hi,

I have a cube and this cube has two zones. The first is a very small zone and is just a constant source term of a gas (Kg/m^3 s) while the other one is porous and initially is filled with air. There is some sort of absorption within the porous media of that gas and not for the air. In Fluent, the solid particles in the porous media are imaginary. I would like to account for this absorption as a UDF sink term to be hooked in the transport equation of that gas. My question is, how can I get the mass fraction of the gas in the volume of voids and not in the imaginary solid volume? The problem is Fluent consider the entire porous volume as fluid and does not consider the porosity for the gas fraction.

My sink term is in Kg/m^3 s (dC/dt = f(time); represents the rate of change or the absorption). I wrote a UDF with DEFINE_EXECUTE_AT_END and within it, I put a condition if the mass fraction of the gas multiplied by the density (kg/m^3) is higher than dC = f(time )*dt (the amount to be absorbed) then the sink term is valid otherwise is equal to zero. Then a DEFINE_SOURCE for the sink term.

I was told that the sources in porous need to be scaled by the porosity function but I do not understand what does this mean. And how can I get the correct mass fraction?

Other question, from the mass fraction, is there a way to get kg/m^3 s) out of this mass fraction in the UDF?


Please help! Than you,
Gomaa is offline   Reply With Quote

Reply

Tags
mass fraction, porous, udf

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Inconsistencies in reading .dat file during run time in new injection model Scram_1 OpenFOAM 0 March 23, 2018 23:29
UDF to Define Species Mass Fraction on Velocity-Inlet MiBe Fluent UDF and Scheme Programming 3 August 3, 2017 05:36
Define mass flow profile with regards to species mass fraction danS Fluent UDF and Scheme Programming 0 June 20, 2017 07:21
PB: Saving mass fraction of species on two points with an udf biget.a FLUENT 2 July 23, 2009 04:06
UDF for Species mass fraction Rahul FLUENT 0 September 20, 2002 05:22


All times are GMT -4. The time now is 14:24.