Volume fraction of dispersed phase to determine DPM, VOF, Mixture model
Hello
For using DPM model in fluent, volume fraction of disperesed phase should be below 10% to 12 %, otherwise you have to look for other models such as mixture and VOF models in fluent. For determining Volume fraction of a particle, the following formula is used: alpha=NpVp/Vc where alpha= volume fraction of solid phase Np=Number of particles Vp=Volume of particle Vc= Volume of the container or total volume of the cylinder or the whole control volume. If alpha comes out to be greater than 12% then "mixture" or "VOF model" would be considered for dense phase. Please comment if the above statements are correct/wrong. Thank you so much. Mohsin |
Hi,
The whole idea is right but some other points should be noted: - Actually this range is not very tight; it's just a rule of thumb, I believe that if Lagrangian modeling could be proper for a case we can use it. - Note that DPM modeling in FLUENT encounter many bugs in brownian motion and computing deposition, so in many cases in which diffusion term is dominant in dispersion; such as nano-particles, we have to use eulerian modeling, i.e. solving a transport eq. to find particle concentration. Amir |
Well, Amir, thank you very much for the guidance. Added to ur reputation:)
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Hi Amir,
I am simulating gas-solid flow with two fluid approach with fluent and I am trying to have 20% mass loading of the particle at the inlet. as it is same inlet for both phases area is not important... my air density is 1.2 kg/m3, velocity is 9.3 m/s. solid density is 2500 kg/m3 , I think velocity must be calculated but I am not sure or I can use 9.3 for solid as well? how I can calculate the uniform volume fraction of the solid at inlet while assuming constant particle to gas velocity ratio? do you have any idea? thanks in advance! |
how to define volume fraction in dpm
i have slurry jet (water and sediment).i cant define volume fraction for this problem.i define injection from surface.....
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Volume fraction of dispersed phase to determine DPM
Hello Mohsin,
How can we calculate? Np=Number of particles, Even if we calculate the number of particles by assuming a volume fraction how to input them in fluent? Thanks and regards, Nitin K |
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