Learning Forum

[gmk29]

I am simulating two gases mixing in a T-junction, which are found in the Ansys data base. Initially, I selected species transport as the model and was able to select Full Multicomponent Diffusion with the default mixture material. When I defined my new mixture with the two gases, I also selected multicomponent for mass diffusivity and put it at a constant value. When I went back to species transport and selected this new mixture, it grayed out the Full Multicomponent Diffusion option and I am unable to select it when I have this new mixture chosen. I am new to Ansys so would appreciate some guidance as to what may be causing this. For reference, here are my steps:

1) General Settings: Solver

1) Type: Pressure-based

2) Velocity Formulation: Absolute

3) Time: Steady

2)General Settings: Gravity

1) X: 0 m/s2

2) Y: -9.81 m/s2

3) Z: 0 m/s2

3) Models

1) Species: Species Transport

2) Reactions: none

3) Options: Diffusion Energy Source + Full Multicomponent Diffusion

4) Materials

1) Fluid: gas1 and gas2

2) Mixture: gas1_gas2_mix

1) Names: gas1 and gas2

2) Density: ideal-gas

3) Cp: mixing-law

4) Thermal Conductivity: mass-weighted-mixing-law

5) Viscosity: mass-weighted-mixing-law

6) Mass Diffusivity: multicomponent = constant

5) Species Transport

1) Mixture Material: gas1_gas2_mix

[Rob]

If your mixture is only two species why would you need multicomponent?