Q. Can I set the density as a function of another variable such as salinity and Temperature.
A. By default, in CFX-5 the user can set an expression for a Material Density to be a function of Pressure, Temperature, and the coordinates (X,Y Z) . This is defined in the RULES file, (see the manual about the RULES file and its location). This may be changed to be a function of other variables, through some simple CCL.
A file den.ccl containing the following information:
RULES:
PARAMETER: Density
# Build Name = Density
# #Allowed Parent List = FLUID TYPE
Description = Material density
Parameter Type = Real
Quantity Type = Density
# Dependency List = p, T, XYZ, pabs
Dependency List = ANY
Solver Name = DENSITY
Lower Bound = 0.0 [kg m^-3]
END
END
would allow Material Density to be a function of ANY quantity. The user would include this through the GUI or with the command line
cfx5solve -def 'def file' -ccl den.ccl
Note that for a complex case, eg a compressible mixture, it is important that the overall thermodynamics is self-consistent, or convergence difficulties could occur.
For a multi-component fluid, the density of the mixture is a function of the Material Density of the components, using some form of Mixing Rule. By default, an Ideal Mixture rule is used. See the CFX-5 User Manual for more information. A user could also make the Mixture Density a function of other quantities, eg salinity, by specifying the quantities as Mass Fractions.
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Q. Can I set the density as a function of another variable such as salinity and Temperature. A. By default, in CFX-5 the user can set an expression for a Material Density to be a function of Pressure, Temperature, and the coordinates (X,Y Z) . This is defined in the RULES file, (see the manual about the RULES file and its location). This may be changed to be a function of other variables, through some simple CCL. A file den.ccl containing the following information: RULES: PARAMETER: Density # Build Name = Density # #Allowed Parent List = FLUID TYPE Description = Material density Parameter Type = Real Quantity Type = Density # Dependency List = p, T, XYZ, pabs Dependency List = ANY Solver Name = DENSITY Lower Bound = 0.0 [kg m^-3] END END would allow Material Density to be a function of ANY quantity. The user would include this through the GUI or with the command line cfx5solve -def 'def file' -ccl den.ccl Note that for a complex case, eg a compressible mixture, it is important that the overall thermodynamics is self-consistent, or convergence difficulties could occur. For a multi-component fluid, the density of the mixture is a function of the Material Density of the components, using some form of Mixing Rule. By default, an Ideal Mixture rule is used. See the CFX-5 User Manual for more information. A user could also make the Mixture Density a function of other quantities, eg salinity, by specifying the quantities as Mass Fractions. |
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