Hello fluent users,
Currently I am working on Discrete Phase Modeling (DPM) and I am encountering few problems. I appreciate it if you can help.
My case is steady continuous flow with steady particle injections, one way coupling with no interactions.
1. I am using surface type injection from inlet, however, the number of particles is restricted by the number of meshed cells at the inlet (no specified number of streams like point or group injection types) . Can I increase the number of particles without changing mesh density?
2. I would like to display location of the particle on a 2 D plane; is their a method to do this?
3. How can I plot the residence time distribution at outlet knowing that my study is steady bulk/ continuous flow and steady particle injections?
Graphics> particle track> in the left side of window tick Draw mesh and apply default values. > Track Style-----Point> select the particle> then click on Display.
You can increase the number of particles by providing separately, different entry location, velocity and particle size. You can also inject the particle cloud/group. The mesh density will be depend on the size of smallest particle. To display location of particle you can use any post-processing program. By using such program, you can plot time distribution at outlet.
Thank you for reply.
However, I am using massless particles which means that the diameter of the particles is not considered.
Do you suggest another method for increasing the number of particles without varying mesh density?
Hello Walid,
What comes to my mind from my past experiences with particle tracking, mesh size is determined by the smallest particle size, and mass injection or number of the populations to be tracked is independent from the mesh dimensions.
You can use UDF and also by increasing number of streams in group type of injection you can increase number of particles.
Graphics> particle track> in the left side of window tick Draw mesh and apply default values. > Track Style-----Point> select the particle> then click on Display.
Dear friends,
im also injecting particle by using of DPM.
i want to change the absorption coefficient of the particle.think have to used UDF but dont know how to do that. can anyone help me
Hi Walid Abou Hweij sir,
To increase the number of injections from the same mesh size go to:
Models>>Discrete phase>>Injections>>Create injections/set>>turbulent dispersion>>Enable Discrete random walk model and increase the number of tries to 2 or more to increase the number of injections.
to check this go to
Results>>Graphics>>particle tracks>>set up>>In color by select Particle variable>>particle diameter and click on display.
I am thinking this approach is correct if i am wrong correct me
Thanks.
The particles used are massless; hence no particle mass flow option available
Please, how do one specify the volume fraction in DPM in Ansys. I need the equation to calculate the flow rate. I am working on nano fluid (i.e. nanoparticles + water)
Many thanks.
Hi Saheed Adio , please provide little bit more details. What do you mean by specifying the volume fraction? The equation of calculating flow rate is Q=Av, where Q = volumetric flow rate (m3/s), A=area of pipe or inlet (m2), v=velocity in m/s.
Hello Hafiz A. Ahmed , thanks for your response, by specifying the volume fraction, I mean the percentage volume of the nanoparticle(Al2O3) inside the computational domain.e.g 0.2% volume fraction of nanoparticle. I need a corresponding particle mass flow rate at the inlet of the computational domain in ansys fluent Discrete Phase Model to give the required volume fraction of the nanoparticle.
Saheed Adio, Its been a while ago since you posted your reply. However, here are my two cents on it.
As you may know, DPM is usually employed for discrete phase below 10% vol fraction (m3 of particle / m3 of fluid). So , you already have calculated the volumertic flow rate of the fluid phase using the formula Q = A * V. Now, by multiplying this Q with density of the particle will give the mass flow rate of 100% particle loading. For 0.2 % volume fraction, multiply it with 0.2/100 = 0.002. The value you get will be the particle mass flow rate of 0.2% vol fraction.
Hope this answers your question. Please correct me if I missed something.
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