I am trying to track the movement of biomass particle as big as 5mm diameter in FLUENT but have no idea which model to use and where to define the diameter of the particle.

In the following stage, I hope to include combustion in the model. I have read an example provided by FLUENT but it is for pulverized coal, where the 'rosin-rammler' diameter distribution method is use. Unfortunately, it is for particles sized between 70 micron to 200 micron. Therefore, I'm not sure how to simulate my case of 5mm diameter particle.

I'm really looking forward to seeing some advice from anyone who has done anything similar to this or has any idea of how to tackle such problem.

Thank you in advance.

Hi,Jacklyn:

In your post, it reads that "I have read an example provided by FLUENT but it is for pulverized coal, where the 'rosin-rammler' diameter distribution method is use.".

Could please you tell me where I can find the PDF or file for this example?

best regards.

http://www.iet.aau.dk/~chy/Paper-on-...ticleTrack.pdf

Garano, it is an example from the FLUENT tutorial.

Steve, thanks for the paper! By the way, do you know which solution model to choose in FLUENT if I just want to know the movement of solid particles subjected to an upward gas flow?

We have used Fluent for these types of simulations for about 20 years. Typically, I use a lognormal relationship between the particle diameter and mass fraction. The particle diameters in our situations can be over 25 mm. I would use 25 to 50 diameter classes for the whole range in diameters.

The built in 'rosin-rammler' is okay as well. Fluent uses an even distribution for the particle diameters and then calculates the mass fraction of 'spray' accordingly.

If you have a few weeks, you might want to write your own routine to generate the particle diameters (and velocities and initial locations and mass flow), and read those in as a separate file. The Fluent documentation is pretty good on this.

Good luck.

Hi Allan,

To be frank, I'm a new user of FLUENT and I'm not very familar with what FLUENT can do. Can you tell me more details about how to write the UDF as mentioned in your previous reply? It is possible if you send me a sample of such UDF?

Say now we consider a simple case with no combustion involved, and biomass is injected with air from the side of a furnace and there is an upward flow of gases from the bottom of the furnace. Generally, what are the solvers to be defined if I want to know how the biomass particles flow; the temperature and velocity profiles.

Looking forward to seeing your reply, thank you in advance!!

For the simple case, I would just inject the biomass as inert fuel particles with the appropriate density. Use the Fluent Injection panel and set the initial position in the furnace and then whatever velocities and diameter range you want.

Obviously, this won't work for combustion of the particles. For this, more detailed particle set-up is required. You could do this by just typing in the numbers (x,y,z,u,v,w,d etc.) into a text file. But after awhile, it gets tiring and you probably would want to automate it. More recently, we have used Excel to generate the injection file. In my experience, this is better than writing a UDF. But, check the manual.

I suspect there is something wrong with the solution steps I applied when tracking solid particles. Somehow the results are always 'Unable to locate Injection Stream'...what I got is always the solution for the continuous phase, as if the solid discrete phase never exist. Does anyone know what happen?