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Old   February 18, 2015, 11:36
Default Discrete Phase Modelling in Fluent
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Ravinder Gill
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I have some general questions about DPM in Fluent.
1)How does Fluent estimate the trajectories of particles if you enable the 'interaction with continuous phase' or disable it? What is the difference in two?
2) Is it possible to export the forces acting on a particle? I have looked into it and i could not figure it out. However, i was able to export the velocity magnitude as a function of particle's trajectory.

Thanks in advance.
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Old   February 18, 2015, 14:51
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Cees Haringa
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Hi gill;

1) if you disable interaction with continuous phase, the coupling is 1-way. That means the particle trajectory is influenced by forces acting on the particle from the fluid, but the fluid flow is not influenced by the particles. FLUENT integrates the force balance on the particle; the integration routine is chosen depending on you own settings.

If you enable interaction, the fluid flow is influenced by the momentum of the particles as well. Within a timestep, the fluid trajectory is solved, then the particle trajectory based on that fluid flow. The fluid flow is then updated, based on the particle motions, and afterwards the particle positions are recalculated, on and on until the situation converged within the set residuals.

2) I don't know any way to directly output the forces acting on the particle. You could write a UDF to output this - basically, you need UDF that does the same calculation as FLUENT does, and outputs it to a file.
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Old   March 8, 2015, 19:56
Default DPM problem
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Hi all, iam working on a boiler problem and I am using group injection. My combusting material is coal mv, I am using combusting at material type and the devolatilizing species are mv_vol. The vaporization Temperature of the combusting material is 400K. When I use at injection initial Temperature T=400K, it's all ok, but when I use initial Temperature T=300K I have many problems, such as "Temperature limited to 1 or to 5000K. Is it wrong to have initial Temperature less than Vaporization Temperature?

Thanks in advance,
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