Learning Forum

[Vicky]

Hello,

I am working with the DPM option of Fluent to simulate air and solid particles through a horizontal pipe (pneumatic conveying);
How can I plot the velocity profile of the particles?

My case is unsteady flow with particle injections and two-way coupling.

1. I am using the velocity of the particles equal to the air (10 m/s).
2. I am using surface type injection from the inlet, start time 0 s / stop time 10 s
3. Mass flow rate: 0.003 kg/s / Diameter of particle: 18 mm
3. The model is k-e
4. Time step size: 0.05. Number of time steps: 200

The option 'Data File quantities' is not activated; I tried to activate it through File>Preferences>Legacy; however, when I ran the simulation, I obtained an Error.

In addition, I tried to export the information of the particles (particle velocity magnitude), but the only option to save the file is .h5; therefore, in the Post processing, it is not possible to import the file.

How can I plot the velocity profile of the particles?

 

 

 

 

 

[Rob]

DPM data is tracked on the particles, not on the cells (there are some exceptions when you are fully coupled). You may also find pneumatic conveyors to run at a higher volume fraction than DPM is intended for, and the diameter may also be a problem. 

Not sure why you're trying to write out particle data, if you save a .dat.h5 or .dat.gz along with the case it'll post process fine in Fluent. Particle tracks and CFD Post can be a little messy. 

[Vicky]

Hello,

Thank you for answering.

The volume fraction is less than 0.001, so the DPM option should work. 

Regarding the file type, I read that .dath5 is incompatible with the CFD post. I wrote out the particle data to obtain the "velocity profile of the particle."

In the CFD post, I could plot the air's velocity profile by just drawing a line and selecting the variables for both axes, but I would like to plan the velocity profile of the particles.

Please, Could you answer the following questions:

1.- Why may the diameter be a problem?

2.- How can I plot the velocity profile of the particle?

 

[Rob]

Don't use CFD Post, do the post processing in Fluent. Post is good for large transient data sets but otherwise I'd leave it. 

In the DPM model we assume the particle volume fraction is small (overall) but also that particles are small compared to the cell size. I don't know how big the domain is, but 18mm diameter particles could be big relative to the mesh. 

The particle does not have a velocity profile. Each track will have a velocity with length (or duration). Or each particle will have a velocity at each time step. Not sure what you're after. 

 

Finally, please don't log multiple threads on related questions. It makes helping difficult, and may mean we duplicate work: that's annoying.