I have to track only one particle freely falling in fluid medium in unsteady (both DPM and flow). In DPM injection I select single particle injection, set particle position and velocity, diameter and mass flow rate. DPM time step 0.00001 and fluid time step 0.001. DPM iterates every 10 flow iterations.
Hi Govind Sharma ,
in the injection settings you can set a start and end time, you can set both the same, but make sure that this will be a point in the future regarding the actual simulation time. Than only one particle should be injected at this time (for making sure that that particle behaves as single particle you should set the particle number in parcel to 1). Setting the DPM time step to the fluid time step, according to my knowledge should give the best accuracy, setting it lower makes no sense for me at a first look.
Thanks Christian.
I did the same as you suggested, set the start and end time at 0 and 1 particle in parcel. But still I do not find particle injection. Smallest grid size is 0.001m and particle diameter is 1/4 of this grid size. I set the mass flow rate according to this diameter and density of particle (m = rho*volume). I want to trap particle in the domain for that I set top boundary as escape and others reflect. I am giving flow and particle time step 1.0e-5 with 100 time steps.
Regards,
Govind Sharma
You should try setting the time to lets say 0 and your stop time to 1E-5 (if that is your time step size ) and you really do start from 0. Than you should set the mass flow rate to density times particle volume divided by (1/1E-5), normally this should work...
Thanks Christian.
Yes It works but instead one, there two particles and why do you say to set stop time as time step?
Regards,
Govind Sharma
You can see how Fluent calculates the number of injected particle in the appended picture. So in the first place you have to set the mass flow high enough that a particle is released. I wasn't sure if start and end time can be the same that a particle release is triggered, but based on you observation, you can set start and end time to zero (the same), then you should get only one particle.
Thanks Christian.
It works now, I can only particle in Console as well graphic window. I set start and time to zero only and calculate mass flow rate as given in manual. Thanks It was good discussion. This is the just to see injection of one particle in fluent. I have to do some physics with this single particle in flow field.
Regards,
Govind
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