Learning Forum

[Oluwagbemiga Fabunmi]

Hello there. I am simulating flow through a porous medium using ANSYS Fluent. There is only one inlet and no outlet. However, when I view the CFD Post, I realize that the values for mass flow rate are all negative. This is strange to me because the vectors show that the flow is in the positive x direction as I'd set it up. Why are my mass flow rate values negative?

[Rob]

Please can you post images? What density are you using for the fluid?

[Oluwagbemiga Fabunmi]

I am using water vapour and air, a multiphase flow. There densities are 1.225kg/m^3 for air and 0.552kg/m^3 for water

[Oluwagbemiga Fabunmi]

[Rob]

Vapour enters and condenses? How negative a mass flow are you seeing, and how good is the model convergence?

[Oluwagbemiga Fabunmi]

Yes, vapour enters and condenses. The magnitude of the negative mass flow rate in captured in the picture; in the region of -7.272e-12. The arrows in the pic are the vectors; pointing in the x-direction; where i set it to flow. The convergence was good. Well below 20 iterations.

[Rob]

And what's the condensation rate? Values at that level may be numerical error so check convergence.