Hi Kurt,

In the high order outflow condition the pressure appears as p n (where n is the normal) and has to be introduced in the relevant velocity component. So if your outflow is normal to the x-direction then the value of p n should appear in the Value of the u-variable.

Cheers,

Spencer.

On 24 Jul 2017, at 22:55, Kurt Sansom <kayarre@gmail.com> wrote:

Hi,

   I am trying to use the higher order outlet boundary conditions. I know that is formulated for truncated open domains, but am curious if I can use in the following way, where I want to specify the outlet pressure to some value to create back pressure in  the system. I realize that for in-compressible flow it doesn't matter that much, but I am interested in implementing a time varying pressure condition at the outlet. 

 I have tried the following boundary condition for a tube and it doesn't appear to apply the VALUE tag? I want to make sure before I file a bug.

<REGION REF="2">
    <!-- Outlet , N=Neumann=gradient, D=Dierchlet=value R=Robin=mixed-->
    <N VAR="u" USERDEFINEDTYPE="HOutflow" VALUE="0" />
    <N VAR="v" USERDEFINEDTYPE="HOutflow" VALUE="0" />
    <N VAR="w" USERDEFINEDTYPE="HOutflow" VALUE="0" />
    <D VAR="p" USERDEFINEDTYPE="HOutflow" VALUE="10665" />
</REGION>

Regards,

 ~Kurt

--

Kurt Sansom

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Spencer  Sherwin

McLaren Racing/Royal Academy of Engineering Research Chair, 

Professor of Computational Fluid Mechanics,

Department of Aeronautics,

Imperial College London

South Kensington Campus

London SW7 2AZ

s.sherwin@imperial.ac.uk

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