Divergence with source UDF for VOF

aleni32 · September 2, 2014, 22:42

Hi everybody
I wrote an UDF for sources (lift, drag, virtual mass forces and K and epsilon) for VOF model two phase(steel and injecting argon). the simulation converged without sources but when the source became activated the simulation diverged suddenly after 1.5 sec with this error:sweeping relaxation factors, divergence in X momentum y momentum, z, k , epsilon- divergence detected in AMG solver: x-momentum', floating point exception .
Global Courant number was stable before divergence.
I did the following procedures:
1- limiting the sources to just above argon inlet and below the free surface
2- changing the URF of sources from 0.1 to 0.05
but still diverging suddenly. I really dont have any idea whether it is a structural error in sources or errors in setting of fluent.
Much appreciated if anybody help me to find the error.

Sun · September 3, 2014, 01:51

Since you mentioned that it worked without the source term, something might be wrong with the source term calculation. If you share your UDF with a short description, I'll have a look. The "floating point exception" error usually happens due to a bad math throughout the code such as division by zero or some variables go to infinity and etc.

aleni32 · September 3, 2014, 06:51

Dear SUN
I would be appreciated if you give me your email. I would send my UDF to you.
Thanks in advance

Sun · September 3, 2014, 10:55

You can send it via private message.

rishitosh · December 28, 2014, 01:16

I m also facing same prlm...

September 2, 2014, 22:42	Divergence with source UDF for VOF	#1
aleni32 New Member Join Date: Sep 2013 Posts: 4 Rep Power: 12	Hi everybody I wrote an UDF for sources (lift, drag, virtual mass forces and K and epsilon) for VOF model two phase(steel and injecting argon). the simulation converged without sources but when the source became activated the simulation diverged suddenly after 1.5 sec with this error:sweeping relaxation factors, divergence in X momentum y momentum, z, k , epsilon- divergence detected in AMG solver: x-momentum', floating point exception . Global Courant number was stable before divergence. I did the following procedures: 1- limiting the sources to just above argon inlet and below the free surface 2- changing the URF of sources from 0.1 to 0.05 but still diverging suddenly. I really dont have any idea whether it is a structural error in sources or errors in setting of fluent. Much appreciated if anybody help me to find the error.

September 3, 2014, 01:51		#2
Sun Senior Member Join Date: Nov 2010 Posts: 103 Rep Power: 15	Since you mentioned that it worked without the source term, something might be wrong with the source term calculation. If you share your UDF with a short description, I'll have a look. The "floating point exception" error usually happens due to a bad math throughout the code such as division by zero or some variables go to infinity and etc. aleni32 and 6863523 like this.

September 3, 2014, 06:51	your email	#3
aleni32 New Member Join Date: Sep 2013 Posts: 4 Rep Power: 12	Dear SUN I would be appreciated if you give me your email. I would send my UDF to you. Thanks in advance

December 28, 2014, 01:16		#5
rishitosh New Member Rishitosh Ranjan Join Date: Dec 2012 Location: Trichirapalli, Tamilnadu, India Posts: 22 Rep Power: 13	I m also facing same prlm... Last edited by rishitosh; December 28, 2014 at 03:18.

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September 3, 2014, 10:55		#4
Sun Senior Member Join Date: Nov 2010 Posts: 103 Rep Power: 15	You can send it via private message.