How can I access in CFX 10.0 the volume fraction of an Algebraic Slip Model (ASM) species, e.g. for the calculation of drag force in User Fortran?
The limitation on volume fraction is caused by settings in the VARIABLES file. You can find this in the etc subdirectory of your installation directory. By default, volume fraction is designed for multiphase cases. You can though extend its scope by putting some additional lines in your ccl:
Physical Availability = ALL
Variable Scope = PHASE,COMPONENT
Variable Class = MCF
You will need to edit the ccl outside the CFX-Pre GUI otherwise the checks will be applied again and your modifications removed.
In your call to USER_GETVAR, make sure that you use the correct syntax for the volume fraction, e.g.:
CALL USER_GETVAR('MyFluid.ASMspecies.Volume Fraction,.........)
where MyFluid is the name of your multi-component mixture.