Learning Forum

[Sifiso Mngonyama]

Hi everyone 

How does one set the diffusion flux equal to zero at the inlets and outlets as a boundary condition to create a closed system in the species model instead of specifying mass fraction? or does fluent assume this condition if you haven't clicked the inlet diffusion option? 

[SRP]

Hi,

I suggest you to refer to fluent user's guide:7.4. Boundary Conditions (ansys.com) 

This will help you to understand the diffudion flux boundary condition.

Thank yoi.

[Sifiso Mngonyama]

Thank you for your reply. However, I didn't get the answer to my question after going through the suggested chapter. The only thing related to the question I found was that the boundary condition Im asking about is the default at the walls. Let me rephrase my question. Some problems at the inlet don't provide a specific species mass fraction (also called Dirichlet boundary condition) but they provide a specific mass flux (or Neumann boundary conditions). In this case, how can I add this mass flux in fluent since at the species option under velocity inlet there is only an option to add species mass fraction only?

[Sifiso Mngonyama]

 

Thank you very much.