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-   -   Turbulent Dispersion in Particle Tracking (http://www.cfd-online.com/Forums/cfx/25688-turbulent-dispersion-particle-tracking.html)

 ariel April 20, 2008 22:56

Turbulent Dispersion in Particle Tracking

This is taken from ANSY Documentation: "If turbulent particle dispersion is enabled, you will need to track a much larger number of particles (usually an order of magnitude higher) since a stochastic method is used. This will greatly increase computational time; therefore, this is most often performed as a post-process where there is only one particle iteration."

I just want to ask what do you mean by "this is most often performed as a post process.."? How can I perform 1 particle iteration in CFX post? Or is it the same as running a smaller number of particles and after it converges, use it as initial values to run a single particle iteration in the Solver using larger number of particles? Thanks guys!

 Kushagra April 22, 2008 18:29

Re: Turbulent Dispersion in Particle Tracking

I understand the same. By the way I am not able to obtain results with Lagrangian Particle Tracking in CFX. My case is a hydrocyclone and I have enabled all the possible forces in CFX-Pre (Turbulent dispersion, drag, gravity, pressure gradient).

Please share with us the level of satisfaction you have with results in your case. I would highly appreciate your information.

 ariel April 22, 2008 22:02

Re: Turbulent Dispersion in Particle Tracking

I think the method used in tutorial 9 is much better than we understood wherein small number of particles are fully coupled to set the effect of particles to the continuous phase. While much larger number of identical particles are assigned as one way coupling. The solver does one particle iteration of one way coupled particles at the end of the solution stage.

I think it's better if you would run it first using all the forces except turbulent dispersion. Then use it as initial values when you include particle turbulence. If you have difficulty in convergence which happened to me at first, play around with the timescale to find the appropriate one for your problem. If you are new to particle tracking, try reading first the solver control manual. It helped me a lot.

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