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-   -   Averaged Sauter Mean Particle Diameter (https://www.cfd-online.com/Forums/cfx/106761-averaged-sauter-mean-particle-diameter.html)

sjtusyc September 7, 2012 08:37

Averaged Sauter Mean Particle Diameter
 
I wanna to get the " Averaged Sauter Mean Particle Diamete " at a specific surface,say outlet.
I turn to the Function Calculator.
But what function should i select,as the Sauter Mean Particle Diameter is an averaged diameter.

I tried areaave, massflowave,minVal,maxVial functions, and i get different results.
*

areaAve_z(water.Averaged Sauter Mean Particle Diameter)@out (it has a direction?)
massFlowAve(water.Averaged Sauter Mean Particle Diameter)@out
massFlowAve(water.Averaged Sauter Mean Particle Diameter)@out

Anyone who has this kind of experience?

Thanks in advance.

sjtusyc September 8, 2012 08:54

I am waiting for your anyone to reply.Thanks

ghorrocks September 9, 2012 06:35

That's because areaAve, massflowAve, minVal, maxVal are all different. It have nothing to do with Sauter mean diameters. Look in the CEL reference guide to understand what these functions mean.

sjtusyc September 10, 2012 03:34

Thank you fore your reply.
I read the corresponding part in the help documentation and is clear about these functions,they just use different weighting factor.
But i was still confused that why there is always an 'averaged' before particle variable.
eg, Averaged Sauter Mean Particle Diameter, 'mean' already means averaged.

murx September 10, 2012 06:36

From the notation of "water.Averaged Sauter Mean Particle Diameter" it seems that it is an output variable of your solver. So it is stored for every control volume. I guess in this case, "mean" means averaged over the control volume (so over 1 cell).
EDIT: I just read the other thread you started. I figured you are trying to simulate a spray and the sauter diameter you are refering to is the diameter of the drops. It's probably a bad idee to try to calculate the sauter diameter of drops that have a specific shape/volume and are smaller than your control volume ;) So forget this part of my answer... :)

If you want to get the average sauter diameter of particles flowing through your outlet, massFlowAve() is probably the function you should use.

sjtusyc September 10, 2012 09:53

Thank you for your elaborate answer.I think you got some points.
There are two kinds of variables.One from Euler point of view,say,control volume
as your said ,nodal value.The other one is from Lagrange point of view,like the SMD i want to get.
It seem that CFD-post only in support of the variable in Euler point of way.


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