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Neser25 February 22, 2007 11:13

variable composition mixture properties
 
I created a variable composition mixture from water and salt particle solid (an aqueous solution), Any way to define its physical and thermodynamic properties as a function of its temperature and salt/water mass fractions.

If not, even by a FORTRAN subroutine, so any way to export the default CFX value of this properties


Opaque February 22, 2007 20:11

Re: variable composition mixture properties
 
Dear Neser25,

By default, the ANSYS CFX solver computes the properties of a mixture as the weigthed sum of the property components i.e.

Mixture prop = sum (Mass Fraction_i * property_i)

Of course, density is computed differently. The formula above is just a crude approximation.. If you do have a different mixture rule, you can do so under the MIXTURE PROPERTIES section for the mixture material.. You can basically override the ANSYS CFX calculation for each property using your own formulas..

Opaque.

Neser February 22, 2007 22:11

Re: variable composition mixture properties
 
Dear Opaque,

Thank you for your reply

Under the MIXTURE PROPERTIES section for the mixture material, the program does not let me use the temperature and water mass fraction as a variables in the formula. I am modelling a spray evaporation process. Therefore, the mass fraction of water in the aqueous solution droplet is variable.

Any way to add the mass fraction to the formula?. If it is not possible, I can set it with its initial conditions before the spraying process. So, any way to define the properties during CFX calculation through a FORTRAN subroutine for example

Regards


HekLer February 27, 2007 17:47

Re: variable composition mixture properties
 
Your only option is to set the properties of the pure substances (in this case water & sand right?).

Other than mixture density the solver assumes the formula printed by Opaque.



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