HOW TO WRITE UDF FOR INTERFACIAL MASS AND HEAT TRANSFER VOF MODEL

- February 10, 2021 at 9:46 am
  
  Nitin_Bansal
  Subscriber
  
  hello,ni am trying to simulate a problem of phase change in which i am using CLSVOF model for tracking of interface. In this i am unable to write a UDF for introduce a source term in the continuity and all other equations at the interface. I know that how to write UDF for boundary condition but unable to write udf for source term. is there any other way of writing UDF for source term?nthanksn
- February 10, 2021 at 1:18 pm
  
  Rob
  Ansys Employee
  
  Source terms are covered in the manual. The hard part from you say above is picking the cells around the free surface. n
- February 10, 2021 at 3:06 pm
  
  YasserSelima
  Subscriber
  
  And the free surface would have high gradient of the volume fraction.n
- February 11, 2021 at 9:42 am
  
  Nitin_Bansal
  Subscriber
  
  ni saw the manual but didn't get idea. In my problem there is a completely filled closed container than how we will decide free surface?nthanksn
- February 11, 2021 at 9:45 am
  
  Rob
  Ansys Employee
  
  If the chamber is completely filled how will it boil? n
- February 11, 2021 at 9:46 am
  
  Nitin_Bansal
  Subscriber
  
  nwhat do you want to say please describe?nand according to you which surface should be consider as free surface nthanksn
- February 11, 2021 at 9:52 am
  
  Nitin_Bansal
  Subscriber
  
  nupper half portion is considered to be filled by vapor which is treated as ideal gas and all the fluid is initialize at saturation temperature, so as heat is provided evaporation takes place and pressure of container is keep rising
- February 11, 2021 at 9:54 am
  
  Nitin_Bansal
  Subscriber
  
  @Rob upper half portion is considered to be filled by vapor which is treated as ideal gas and all the fluid is initialize at saturation temperature, so as heat is provided evaporation takes place and pressure of container is keep risinghttps://forum.ansys.com/discussion/comment/106439#Comment_106439
  i am just trying to study that pressure rise in the container and time taken in that pressure rise.nn
- February 11, 2021 at 9:56 am
  
  Rob
  Ansys Employee
  
  So you do have a free surface. OK, that configuration will work. Have a look at the phase change options in Fluent multiphase, they'll be more reliable than trying to write your own, at least to start with. n
- February 11, 2021 at 2:03 pm
  
  YasserSelima
  Subscriber
  
  And the free surface would have high gradient of the volume fraction.https://forum.ansys.com/discussion/comment/106320#Comment_106320
  I was suggesting a methodology to be able to pick the cells around the free surface in your UDF. But just forget about it. It seems you don't need a UDF. n
- February 12, 2021 at 7:33 am
  
  DrAmine
  Ansys Employee
  
  If you are looking to have a free surface phase change: You will probably require UDF. For that reason add more details!n

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