[sanket_p]

I am using CFX to model a steady state fluid flow and heat transfer of a mixture of two (ideal) gases - CO2 and air. CO2 at a given temperature enters the chamber at inlet with given mass flow rate. The chamber is filled with air. The CO2 leaves the chamber at outlet. Other boundaries are simply no slip walls. For this problem, I have created a variable composition mixture with these two components and have defined the inlet BC as mass flow with mass fraction of CO2 as 1 and similar for the outlet with negative mass flow. Buoyancy has been activated with proper reference state. While running the solver, I am getting the following error even before the first iteration:

+--------------------------------------------------------------------+
| Reference Pressure Information |
+--------------------------------------------------------------------+

Domain Group: Chamber

Pressure has not been set at any boundary conditions.
The pressure will be set to 0.00000E+00 at the following location:
Domain : Chamber
Node : 1 (equation 1)
Coordinates : ( 4.49931E-03, 1.12000E-01,-7.85358E-05).

Domain Group: Chamber

Buoyancy has been activated. The absolute pressure will include
hydrostatic pressure contribution, using the following reference
coordinates: ( 3.90000E-01, 1.00000E-02, 3.40000E-03).

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Stopped in routine Could not find phase directory. |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

What does this message mean? Any guidance will be much appreciated.

[Opaque]

Are you using any kind of CEL expression that requires phase, or material tagging? Say

Fluid.Material.Mass Fraction

or similar.

Otherwise, we may need more information.