[fazzesco]

Hi,
I am working on a axisymmetric multiphase simulation (in the picture), about the impact of a droplet over a wall with dynamic contact angle, defined by this expression:
IF(vrad>0,110[deg],65[deg])
Now, I want to define vrad (radial velocity) as the y velocity evaluated at the ymax. ymax is the max point over the wall where the phase 2 (water) is equal to 1.
I don't know how to write in Fluent expression vrad and ymax.

Can anyone familiar with the Fluent expression help me? Thank you

[Jiaxin*]

could you share your UDF code, i have conducted relevant research before. I need to judge whether the logic is correct or not based on the statement before and after it and also the code can help me clearly understand your meanings. my email is 870254031@qq.com.
looking forward to your reply, because i also have some issues i'd like to discuss with you about droplet impacting.

[fazzesco]

Originally Posted by Jiaxin*

could you share your UDF code, i have conducted relevant research before. I need to judge whether the logic is correct or not based on the statement before and after it and also the code can help me clearly understand your meanings. my email is 870254031@qq.com.
looking forward to your reply, because i also have some issues i'd like to discuss with you about droplet impacting.

I did not use an UDF, but the Fluent function Expression, cause I am bad in C programming.

[Jiaxin*]

Originally Posted by fazzesco

I did not use an UDF, but the Fluent function Expression, cause I am bad in C programming.

how do you realize the function of dynamic contact angle without UDF?
if you use the VOF function, could you share the expression in detial?

[fazzesco]

In latest Fluent version there is the function "expression" (https://www.ansys.com/blog/tips-and-...nsys-fluent-ui).
For instance, what I am trying to do, is using the IF function.
IF(<expr>,<vector>,<vector>)
If the first term is true, the output value is the first vector, if it is false, the output value is the second vector.
IF(vrad>0,110[deg],65[deg]) so, if radial velocity is positive, the DCA is equal tto the advancing value (110° in my case), else is receding (65°).

Unfortunately, I have not already found an efficient condition for the IF function.

[Jiaxin*]

dear friend,
i have known your meaning, which attract me to discuss with you.
i still have some questions:
1) i have read the link you gave, but i don't find the definition of "IF" function in the website, which is the most important to know. you'd better screenshot the definition of "IF" function from the HELP file. or you could tell me which version of the software, i will download the help file to find the definition.
2) your simulation is related to multiphase flow,water phase and vapor phase, so the definition of radial velocity is not clear, the software can't discern what is water, automatically. could you tell me where to set the dynamic contact angle in the software by screenshot?
3) i have the UDF about the dynamic contact angle, if you want, i could share it with you. but i still don't understand some codes in the UDF.

[fazzesco]

1) I am using the 2021 R1 version. I link the screenshot of IF statement from guide, but it is not different from what i wrote before.
2) In the software version that I am using, you can create some Named expressions (last menu in Setup). Then, when you select the contact angle between phases, you select the expression you created.
3) Please, yes share with me your UDF. Did you write it?
My email is giovanni.fazzone@mail.polimi.it