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-   -   Orourke collision model in DieselSpray (https://www.cfd-online.com/Forums/openfoam/96701-orourke-collision-model-dieselspray.html)

kikko January 30, 2012 06:37

Orourke collision model in DieselSpray
 
Good morning,
I want to use the ORourke collision model for my simulation but I have see that I can set only 0 or 1 for the the coalescence coefficient...is it true???
if I set 1 all the particle coalesce and the diameter became too big...
If I set 0 no particle coalescence...
Open Foam don't permit me to set an intermediate value.
Does exist an intermediate case???
Is there another parameter to set for the coalescence????
Thank all for attention
Enrico

niklas January 30, 2012 09:15

coalescence is not a scalar, it is a boolean.
it is a flag you set if you want to allow parcels to coalesce or not.

so either you have coalescence true or false, 'intermediate' values makes no sense.

Rid@foam November 27, 2020 12:54

collision and coalescence models in sprayFoam
 
Hello Niklas sir.
I am using sprayFoam in OpenFOAM-6 and I want to implement collision and coalescence between two particles. I have some questions regarding this, which, if you answer, it will be very helpful.
  • 1) Are there other collision and coalescence models available other than O'Rourke and trajectory?
  • 2) Is the code for coalescence for trajectory the same as for O'Rourke?
  • 3) I was studying the code in the Trajectory.C file where I found the following.
Code:

if (mag(det) > 1.0e-4)
            {
                beta = -(n2d - n1n2*n1d)/det;
                alpha = n1d + n1n2*beta;
            }

            alpha /= magU1*dt;
            beta /= magU2*dt;

            // is collision possible within this timestep
            if ((alpha > 0) && (alpha < 1.0) && (beta > 0) && (beta < 1.0))

What are the significances of these parameters alpha and beta in determining the possibility of collision at a particular timestep?


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