Learning Forum

[ll00023]

LES case with DPM model.

particle tracks results show some particle appears out of the computational domain.

there is no mesh in the white region.

view angle is set to front.

result is converged well.

[Rob]

DPM particles can occasionally escape, but if the mesh is good then it's very rare. I assume the domain is an extrusion of what you're showing? What is Fluent reporting in the TUI for the particle tracks?

[ll00023]

Here is the FLUENT report.

[Rob]

But no aborted or incomplete. If it's just a few that are missing it's probably not going to alter the results. 

[ll00023]

It seems that only a few particles are there.

Thank you, Rob, for helping me check this, and have a great Chinese Dragon new year ????

[ll00023]

the wall boundary condition for DPM is set as reflect; as shown below.

discrete phase reflection coef is polynomial. it is just elastic reflection.

if particle is spotted out of the computational domain,  does this imply that the FLUENT code to predict particle-wall interaction has some loophole? if so, is it trustworthy about the particle-flow-wall interaction result? We would like to know where the particle goes in the system. how to estimate the credibility of the result of particle?

[Rob]

I need to answer carefully, and can't answer in full. 

DPM uses the Lagrangian frame, so different to the flowfield. Particle position & trajectory are updated at intervals, typically on entering a cell and some points on the way through a cell. All basic stuff, and covered in the manual. If your flow isn't resolved (cell with very high velocity) or the cell is poor quality it's possible the particle trajectory check doesn't get an update until it's outside of a cell: in your case outside of the domain. Nothing wrong with the algorithm. 

[ll00023]

I will check the manual about the DPM. Thank you.