Learning Forum

[c.bruno]

Hello everyone,

I would like to compute the residence time of blood in my CFD simulations (steady state). 

I know I can use the DPM model but I would like to have a spatial distribution of the residence time to do something like this in post-processing:

I have read that I can use these macros: P_TIME0 and P_TIME, so I wrote a udf but when running my simulation at the first iteration I get abnormal exit which I think is due to the udf.

This is my udf:

I am not sure if I can use P_TIME0 and P_TIME in a define_execute_at_end function. I have tried to use define_dpm_source but I couldn't understand how to return the values or save them in S. Also, I do not know if the pointer p to the particle is correctly used in my udf.

Does anybody know how to solve this?

Thank you!

[SRP]

Hi,

For more details on define_dpm_source please refer to fluent customization manual: 2.5. Discrete Phase Model (DPM) DEFINE Macros (ansys.com)

If you are not able to access the link, please refer to this forum discussion: https://forum.ansys.com/forums/topic/using-help-with-links/#latest

Thank you

Saurabh

[DrAmine]

I think you need to use the approach of "Mean Age of Air" with UDS if you want a spatial distribution.

Your UDF is wrong as you are trying to use Particle related variables in Eulerian Sense.