Negative mass flow rate in a transient fluent

- August 16, 2023 at 10:53 am
  
  Oluwagbemiga Fabunmi
  Subscriber
  
  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?
- August 16, 2023 at 11:02 am
  
  Rob
  Ansys Employee
  
  Please can you post images? What density are you using for the fluid?
  - August 16, 2023 at 11:16 am
    
    Oluwagbemiga Fabunmi
    Subscriber
    
    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
- August 16, 2023 at 11:13 am
  
  Oluwagbemiga Fabunmi
  Subscriber
- August 16, 2023 at 11:22 am
  
  Rob
  Ansys Employee
  
  Vapour enters and condenses? How negative a mass flow are you seeing, and how good is the model convergence?
  - August 16, 2023 at 11:28 am
    
    Oluwagbemiga Fabunmi
    Subscriber
    
    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.
- August 16, 2023 at 1:15 pm
  
  Rob
  Ansys Employee
  
  And what's the condensation rate? Values at that level may be numerical error so check convergence.

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