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-   -   Normal to boundary velocity (https://www.cfd-online.com/Forums/openfoam-pre-processing/62127-normal-boundary-velocity.html)

 alberto January 21, 2006 20:39

I have to model a pipe with a

I have to model a pipe with a circular corona inlet all around the pipe circumference.

I have to specify a velocity normal to this boundary. How can I do it in OpenFOAM?

Alberto

 mattijs January 23, 2006 05:30

surfaceNormalFixedValue (in Op

surfaceNormalFixedValue (in OpenFOAM/lnInclude/surfaceNormalFixedValueFvPatchField.H)

needs a 'refValue' entry which is the outwards pointing velocity (so negative for inflow)

 alberto January 23, 2006 18:30

Thanks!

Thanks!

 braennstroem June 21, 2007 10:12

Hi, it seems that I have a

Hi,

it seems that I have a similar problem... I would like to calculate a hvac duct and have to set the inlet velocity normal to the boundary. Unfortunately, I do not understand, what Mattijs wrote as a hint!?

Regards!
Fabian

 alberto June 21, 2007 14:11

If the boundary is flat, use f

If the boundary is flat, use fixedValue and specify the appropriate components of the velocity.

If it's not flat You can use:

type surfaceNormalFixedValue;
refValue uniform Umag;

As Mattijs said, if you want your flow to enter your domain, Umag has to be negative.

Regards,
Alberto

 rswbroers June 22, 2007 02:39

Hi, On a similar note, if I

Hi,

On a similar note, if I were to simulate boundary layer suction or blowing, would it be valid to use an ordinary wall boundary condition with a (strictly) normal velocity specified (either by using fixedValue or surfaceNormalFixedValue), or would a specialized boundary condition need to be build?

Also, could, for moderate normal velocities, a wall function still be used? Or will a low-Re turbulence model be required?

best regards,
Roland

 braennstroem July 3, 2007 08:16

Hi Alberto, thanks for the

Hi Alberto,

thanks for the help!

Regards!
Fabian

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