how to set Neumann boundary condition for a UDS in Fluent

  • Last Post 11 March 2019
  • Topic Is Solved
qooin posted this 10 March 2019

I added a UDS in Fluent. Now I want to set the gradient of the scalar at the domain boundary as zero(say, outflow boundary condition). how can I set it?  which UDF macro does it need?

Thank you in advance for your help.

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abenhadj posted this 10 March 2019

Zero flux is zero gradient. No UDF is required.

Best regards,


qooin posted this 11 March 2019

Thanks for your reply.

You mean set specified flux to zero in the boundary condition dialog box? But there is no diffusion term in my UDS equation;The diffusion coefficient is zero.  Does this way work in my case?

abenhadj posted this 11 March 2019

Yes: zero flux is equal to zero gradient at boundary.

Best regards,