The gradient of void fraction in UDF

July 11, 2006, 18:49

Hello, everyone. Now I used the UDF to define the gradient of void fraction as follows: if(NULL!=THREAD_STORAGE(mix_thread,SV_VOF_G)) { v_s=C_VOF_G(c,thread_g)[1]; //Message()"it is OK!%f\n",v_s); } Next, I would like to multiply this gradient of void fraction into velocity(two vectors). In math, I know we could multiply them in x, y direction, respectively. How can I realize this since I do not know how to get the expression of this gradient in x and y direction? (Now I am using 2d) Thanks in advance.

July 17, 2006, 11:03

Do you want scalar multiple product , for example A & B by udf?

motahar · May 20, 2011, 03:34

Hi friends,
I'm simulating a tube with water flow.
The tube encounters boiling near the wall.
I intend to calculate 'void fraction versus enthalpy' along the channel.
Can you help me how to calculate void fraction?

I'm in an emergency condition.
Waiting for your comments!!!

Thanks Everybody

July 11, 2006, 18:49	The gradient of void fraction in UDF	#1
summer Guest Posts: n/a	Hello, everyone. Now I used the UDF to define the gradient of void fraction as follows: if(NULL!=THREAD_STORAGE(mix_thread,SV_VOF_G)) { v_s=C_VOF_G(c,thread_g)[1]; //Message()"it is OK!%f\n",v_s); } Next, I would like to multiply this gradient of void fraction into velocity(two vectors). In math, I know we could multiply them in x, y direction, respectively. How can I realize this since I do not know how to get the expression of this gradient in x and y direction? (Now I am using 2d) Thanks in advance.

July 17, 2006, 11:03	Re: The gradient of void fraction in UDF	#2
Asghari Guest Posts: n/a	Do you want scalar multiple product , for example A & B by udf?

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May 20, 2011, 03:34		#3
motahar New Member M. A. Join Date: Jul 2010 Posts: 27 Rep Power: 15	Hi friends, I'm simulating a tube with water flow. The tube encounters boiling near the wall. I intend to calculate 'void fraction versus enthalpy' along the channel. Can you help me how to calculate void fraction? I'm in an emergency condition. Waiting for your comments!!! Thanks Everybody