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non reflecting version of Navier Stokes characteristic boundary condition

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Old   June 13, 2020, 00:39
Default non reflecting version of Navier Stokes characteristic boundary condition
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Weiqiang Liu
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Hi all,

I tried to reproduce results in a paper and found the boundary condition setting which is described by the author like follows:

"For inflow and outflow boundary conditions ,a non reflecting version of Navier Stokes characteristic boundary condition is applied"

I am wondering what is non reflecting version of Navier Stokes characteristic boundary condition? How can I implement it in fluent?

Best regards

Weiqiang
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Old   June 14, 2020, 10:17
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Lucky Tran
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These are boundary conditions for preventing unwanted reflection of acoustic waves at boundaries. See Pointsot and Lele and Kim and Lee. When running transient compressible flow calculations, acoustic waves can build up inside the domain and eventually trigger an acoustic mode because the normal inlet and outlet BC's are acoustically reflecting.

Note that Fluent already has a wave transmissive boundary condition which is designed for the same purpose.
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Old   June 14, 2020, 11:03
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Quote:
Originally Posted by LuckyTran View Post
These are boundary conditions for preventing unwanted reflection of acoustic waves at boundaries. See Pointsot and Lele and Kim and Lee. When running transient compressible flow calculations, acoustic waves can build up inside the domain and eventually trigger an acoustic mode because the normal inlet and outlet BC's are acoustically reflecting.

Note that Fluent already has a wave transmissive boundary condition which is designed for the same purpose.
Hi,

Thanks for your answer!

Best

weiqiang
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