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Fluent: temperature of UDF mass source

    • Ayaaz Yasin

      Is there a way to set the temperature of the new mass being added by a UDF mass source? I ran a simple test case and it looks like the UDF mass source adds new mass at a constant 298.15 K. However, I could not find a way to change this temperature. The only solution I have is to add a heat sink UDF to the same domain and remove enough heat to cool the new mass to the desired temperature (~21 K). This does not work as intended and cools the neighboring region as well. Is there a way to directly change/set the temperature of the UDF mass source without the need for additional UDFs? 

    • Atharva Nagarkar


      The temperature can be set by specifying the appropriate energy source. For the energy equation, add a source that is to be calculated from the mass source, the heat capacity (Cp) and the desired temperature. If no adjustment to the energy equation is made, the species sources are treated as entering at T_ref  = 298.15 K. Here is the link from the Ansys manual on how to add a source term in a UDF. 

      2.3. Model-Specific DEFINE Macros ( - Check section 2.3.43

      Note that you should add momentum sources unless the mass that enters is at rest.

      If you are not able to access the link, please refer to this forum discussion: Using Help with links (


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