[372316422@qq.com]

Hello, I want to simulate particle concentration decay in a room, and need to set a initial particle concentration for this room. Could you tell me how to do it, and which model is suitable for this problem.

[anawana]

you can use patch to initial the particle concentration

[372316422@qq.com]

Originally Posted by anawana

you can use patch to initial the particle concentration

But when I enable the DPM model, there is no relate choice about particle concentration in the patch pannel.

[mprinkey]

If you are using DPM in Ansys FLUENT, the model doesn't (or at least, didn't used to) work that way. It was not a DEM-type solver where the particle locations and the fluid properties were integrated together in time. DPM (at least, used to) exist outside of the fluid solution loop and would do particle tracks through the fluid using the current velocity and temperature fields. The code did the bookkeeping to accumulate statistics that could then be feed back into the fluid flow as source terms. But all of the particle tracks (at least used to) need to terminate by hitting a wall with some adhesion rule, exiting through an outlet, or burning up completely.

So, based on initial particle distribution, I think you need to look to another model. If the particles are very small, you can use one of the simple multiphase eulerian models. If the particles are large and significantly effect the gas motion, you can either use a full DEM model (as in OpenFOAM or MFIX) or two-fluid eulerian model.

[372316422@qq.com]

Originally Posted by mprinkey

If you are using DPM in Ansys FLUENT, the model doesn't (or at least, didn't used to) work that way. It was not a DEM-type solver where the particle locations and the fluid properties were integrated together in time. DPM (at least, used to) exist outside of the fluid solution loop and would do particle tracks through the fluid using the current velocity and temperature fields. The code did the bookkeeping to accumulate statistics that could then be feed back into the fluid flow as source terms. But all of the particle tracks (at least used to) need to terminate by hitting a wall with some adhesion rule, exiting through an outlet, or burning up completely.

So, based on initial particle distribution, I think you need to look to another model. If the particles are very small, you can use one of the simple multiphase eulerian models. If the particles are large and significantly effect the gas motion, you can either use a full DEM model (as in OpenFOAM or MFIX) or two-fluid eulerian model.

Thank you very much. Then is the species model(composition PDF transport) suitable for this case?

[mprinkey]

I honestly don't know. I left Ansys several versions ago. I am expert in Fluent 6.3 and earlier. I don't know of the current model compatibilities. But the multiphase models have been integrating more and more of the combustion capabilities. You will just have to read the documentation, talk to your Ansys support tech, or maybe try asking in the Fluent-specific forum here.

[372316422@qq.com]

Originally Posted by mprinkey

I honestly don't know. I left Ansys several versions ago. I am expert in Fluent 6.3 and earlier. I don't know of the current model compatibilities. But the multiphase models have been integrating more and more of the combustion capabilities. You will just have to read the documentation, talk to your Ansys support tech, or maybe try asking in the Fluent-specific forum here.

Thank you very much!