KR25: How to modify DPM injection mass flow using UDF?


If you want to modify injection inputs using UDF, you will require the following DPM macro

DEFINE_DPM_INJECTION_INIT

This macro provides access to particle variables like number of particles in a parcel "p->number_in_parcel", DPM mass flow rate "P_FLOW_RATE(p)" etc.

These variables are linked as follows:

Stream mass flow rate = (Number of particles in a parcel) *(Mass of single particle) / ( Injection time interval)
If you want to modify the mass flow rate, you should modify it using P_FLOW_RATE(p) and not by modifying p->number_in_parcel. This is because p->number_in_parcel is derived from P_FLOW_RATE(p).
In general, p->number_in_parcel should never be modified in the UDF.
Mass flow rate should be modified by changing P_FLOW_RATE(p) only.





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