Cant control the number of parcels injected by my UDF

[Luis.Otavio.Cortes.Magalhaes]

Hi everyone!

 

I have set up an UDF for a transient simulation with a time dependant particle mass flow rate (PP_FLOW_RATE(p)) and temperature (PP_T(p)). But the ammount of parcels being injected into my simulation remains contant throughout the whole simulation and the function PP_N(p) has no effect whatsoever. i am only using the DEFINE_DPM_INJECTION_INIT macro so far.

Can anyone help me?

 

[Rob]

Why do you need to control the number of parcels? 

[Luis.Otavio.Cortes.Magalhaes]

Because im running into divergence issues (that only happen with the dpm model turned on) and i think one of the reasons could be the excessive number of parcels in the simulation domain (around 50k parcels in a 200k element mesh)

[Rob]

It's rare for too many parcels to cause a problem as the more parcels the more dispersed the source terms. However, have you looked at where the DPM mass is? That may be more helpful. Pictures will help too. 

[Luis.Otavio.Cortes.Magalhaes]

Usually the region with unphysical values of temperature and high values of particle accumulation is the bottom of the wall in the middle of the domain and sometimes the corners of the domain. (the particles are injected in the inlet surface)

Pictures below are the simulation domain, the dpm concentration shortly before the solution diverges and the massflow function for the particles respectively:

[Rob]

Yes, you'll have particle mass accumulating in regions and the DPM source terms may then cause you some problems. It's mass not parcel count related.