## Fluids

Topics relate to Fluent, CFX, Turbogrid and more

#### Multiphase Simulation with Dense Particles

• Aayushya Agarwal
Subscriber

I am running a steady-state  multiphase simulation with two phases. The first phase is modeled as an Eulerian flow, and the second phase is a dense discrete particle. I had two questions about this approach
1) How do I adjust the number of DPM particles injected for the steady-state simulation? I have tried adjusting the mass flow rate of the injection and I still get the same number of particles when I plot the particle trajectories

2) In this simulation I do not have any continuous phase interaction for the DPM. Is there a way to re-use the Eulerian flow with different DPM settings rather than re-simulating both phases?

Thanks

• Rob
Ansys Employee

The number of parcels you inject is dependent on the injection: for a surface that'll be the number of facets on that surface, for other types it'll be number of streams. Stochastic options will then increase the number of streams. That's covered in the User's Guide & Theory Manual. Note, parcels are not particles but the terms have been used interchangeably (and incorrectly) since about Fluent 3 when DPM was added to the code.

If you have a solution and want to change the DPM settings you can do that and continue to run.

• Rob
Ansys Employee

What are you modelling? DDPM and Eulerian have their uses but so does standard DPM: the correct choice is dependent on both the application and required information.

• Aayushya Agarwal
Subscriber

I am trying to model a jet printing process with discrete particles being injected at the top (inlet 1), along with n2 gas through the top and the sides (inlets 1 and 2). I want to obvserve where the discrete particles land on the outlet.

The injection is from a surface also.

So to continue to run, does that mean after the solution is complete, I can change the DPM settings and re-solve the particle trajectories?

• Rob
Ansys Employee

So, higher volume fraction. DPM transitions to DDPM/Eulerian in regions: so you can change the DPM settings and continue the run but it'll take time to flush the old answer out of the domain.