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
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<mailto: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 _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk<mailto:Nektar-users@imperial.ac.uk> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users 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<mailto:s.sherwin@imperial.ac.uk> +44 (0) 20 759 45052
if the forcing is applied in the velocity component what does that mean in terms of how the solver works? does that mean that the forcing term is only applied in solving the Helmholtz part or is it applied in both the pressure poisson and the Helmoholtz solve? Regards, ~Kurt On Tue, Jul 25, 2017 at 3:40 PM, Sherwin, Spencer J < s.sherwin@imperial.ac.uk> wrote:
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 _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk https://mailman.ic.ac.uk/mailman/listinfo/nektar-users
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 +44 (0) 20 759 45052
-- Kurt Sansom
Hi Kurt, The forcing is applied to the momentum equation rather then the velocity component. It is added as an explicit term which means it will appear in the Neumann pressure boundary conditions, the pressure Poisson solve forcing and in the Helmholtz solve for consistency. Cheers, Spencer. On 19 Mar 2018, at 18:32, Kurt Sansom <kayarre@gmail.com<mailto:kayarre@gmail.com>> wrote: if the forcing is applied in the velocity component what does that mean in terms of how the solver works? does that mean that the forcing term is only applied in solving the Helmholtz part or is it applied in both the pressure poisson and the Helmoholtz solve? Regards, ~Kurt On Tue, Jul 25, 2017 at 3:40 PM, Sherwin, Spencer J <s.sherwin@imperial.ac.uk<mailto:s.sherwin@imperial.ac.uk>> wrote: 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<mailto: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 _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk<mailto:Nektar-users@imperial.ac.uk> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users 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<mailto:s.sherwin@imperial.ac.uk> +44 (0) 20 759 45052 -- Kurt Sansom Spencer Sherwin FREng, FRAeS Head, Aerodynamics, Professor of Computational Fluid Mechanics, Department of Aeronautics, Imperial College London South Kensington Campus, London, SW7 2AZ, UK s.sherwin@imperial.ac.uk<mailto:s.sherwin@imperial.ac.uk> +44 (0)20 7594 5052 http://www.imperial.ac.uk/people/s.sherwin/
participants (2)
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Kurt Sansom
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Sherwin, Spencer J