Learning Forum

[Stemphanie_anansu]

How do you evaluate the quality of the particles emitted by the DPM?
I emitted 30,000 particles and half of them emitted incomplete, is this considered a success? If it is not successful, how should I improve it?
I have a residual of 1e-6 for the continuum equation of the flow field before launch, and 1e-8 to 1e-10 for the rest.

thanks

[Rob]

As an aside you're tracking parcels and not particles - it's a terminology issue from when the model was first introduced. 

With 50% incomplete you have a lot of mass stuck somewhere in the domain. That may be a "success" for a separator, but also suggests some more care should be taken with boundary conditions. Using the Particle Tracks panel skip some (with 30k in the system 300 isn't a bad idea) and see where they're going.  Increasing the particle max steps may be a good idea, but use some care otherwise you may be waiting a long time for a DPM update. 

[Stemphanie_anansu]

Thank you for your answer.
My DPM model is for incidence of particle combustion
I checked the DPM and the coarse value is 1000, it distributes the whole space, is 50% incomplete in this case classified as a success?

[Rob]

You can't set incomplete as a success/failure criterion without understanding what is happening in the flow. In a filter system with a poor choice of DPM boundary conditions incomplete could imply particles are stuck somewhere, so it's a success in that I've got 50% separation, or it could be a failure as I've only got 50% separation. In a combustor it means a portion of the fuel is floating around and we don't know why it's not burning or leaving the domain.