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mike April 19, 2006 10:40

dye simulation- dye concentration
Hi Everybody,

I am doing dye injection simulation in water channel with CFX 10. I am using additional variable approach with defining dye as scalar has unit kg/m^3. I am injecting it at a certain point for 1 sec at 0.01 kg/s rate. After this injection I am running it again 20 sec to see how dye moves and to see concentration changes. In CFX post I am creating a point and then a chart of dye vs time at that point. What I am getting is, kg/m^3 vs sec graph. My question is, does this chart show dye concentration at that point with that much of kg in 1 m^3 water? Or to get concentration value, do I have to define anything in CFX pre? Could you please make this point clear?

Thanks alot,


opaque April 19, 2006 10:54

Re: dye simulation- dye concentration
Dear Mike,

What kind of Additional Variable are you using? Specific, or Volumetric..

For an Specific AV, the ANSYS CFX solver will write 2 fields to the results file:

- dye <-- Should be dimensionless - dye.Volumetric <-- Units of concentration

For an Volumetric AV, it will write

- dye <-- Should be in concentration units kg/m^3 - dye.Specific <-- Should be dimensionless

Then, in CFX-Post, you will plot the concentration based on your setup..

Good luck, Opaque

mike April 19, 2006 11:30

Re: dye simulation- dye concentration
Dear Opaque

Thank you very much for your help. I used volumetric, thus dye is in kg/m^3 and shows concentration. And this is kg dye concentration per m^3 water (or water + dye) at that point. Am I right?

Thanks again,


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