Parabolic velocity profile for inlet boundary condition
Dear All, In a stenosed pipe flow problem, I specify parabolic velocity profile u=2*(1−(r^2)), where r=sqrt(y^2+z^2) as seen below. /*<BOUNDARYREGIONS>*//* *//* <B ID="0"> C[7] </B> <!-- Inlet -->*//* *//* <B ID="1"> C[9] </B> <!-- Outlet -->*//* *//* <B ID="2"> C[8] </B> <!-- Wall -->*//* *//* </BOUNDARYREGIONS>*//* *//* *//* <BOUNDARYCONDITIONS>*//* *//* <REGION REF="0">*//* *//* <D VAR="u" VALUE="2*(1-(rad(y,z)^2))" />*//* *//* <D VAR="v" VALUE="0" />*//* *//* <D VAR="w" VALUE="0" />*//* *//* <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" />*//* *//* </REGION>*//* *//* <REGION REF="1">*//* *//* <N VAR="u" VALUE="0" />*//* *//* <N VAR="v" VALUE="0" />*//* *//* <N VAR="w" VALUE="0" />*//* *//* <D VAR="p" VALUE="0" />*//* *//* </REGION>*//* *//* <REGION REF="2">*//* *//* <D VAR="u" VALUE="0" />*//* *//* <D VAR="v" VALUE="0" />*//* *//* <D VAR="w" VALUE="0" />*//* *//* <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" />*//* *//* </REGION>*//* *//* </BOUNDARYCONDITIONS>*//**/ However, since u=0 at wall of the pipe due to no slip boundary condition definition, the calculated value of parabolic velocity profile at the wall (u = 1.5 ) can not be achieved. Is there any way to overcome this problem? Regards, Kamil
Hi Kamil, It is not clear to me why you are imposing an inflow which is not compatible with the wall boundary condition. Why do you want to do this? If you define the parabolic profile as a boundary region which is higher than the wall boundary conditions then this boundary condition will have priority but the wall boundary condition may well then look strange. Cheers, Spencer. On 30 Mar 2015, at 19:57, Kamil ÖZDEN <kamil.ozden.me@gmail.com<mailto:kamil.ozden.me@gmail.com>> wrote: Dear All, In a stenosed pipe flow problem, I specify parabolic velocity profile u=2*(1−(r^2)), where r=sqrt(y^2+z^2) as seen below. <BOUNDARYREGIONS> <B ID="0"> C[7] </B> <!-- Inlet --> <B ID="1"> C[9] </B> <!-- Outlet --> <B ID="2"> C[8] </B> <!-- Wall --> </BOUNDARYREGIONS> <BOUNDARYCONDITIONS> <REGION REF="0"> <D VAR="u" VALUE="2*(1-(rad(y,z)^2))" /> <D VAR="v" VALUE="0" /> <D VAR="w" VALUE="0" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" /> </REGION> <REGION REF="1"> <N VAR="u" VALUE="0" /> <N VAR="v" VALUE="0" /> <N VAR="w" VALUE="0" /> <D VAR="p" VALUE="0" /> </REGION> <REGION REF="2"> <D VAR="u" VALUE="0" /> <D VAR="v" VALUE="0" /> <D VAR="w" VALUE="0" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" /> </REGION> </BOUNDARYCONDITIONS> However, since u=0 at wall of the pipe due to no slip boundary condition definition, the calculated value of parabolic velocity profile at the wall (u = 1.5 ) can not be achieved. Is there any way to overcome this problem? Regards, Kamil _______________________________________________ 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
Hi Dr. Sherwin, I got the issue. I recognized that I have to revise the velocity profile according to the diameter of pipe I used in my analyses as u=2*(1−4*(r^2)). The paper I try to mimic did not give sufficient detail about this issue which leads to this problem. Thank you. Best Regards, Kamil On 31.03.2015 01:24, Sherwin, Spencer J wrote:
Hi Kamil,
It is not clear to me why you are imposing an inflow which is not compatible with the wall boundary condition. Why do you want to do this?
If you define the parabolic profile as a boundary region which is higher than the wall boundary conditions then this boundary condition will have priority but the wall boundary condition may well then look strange.
Cheers, Spencer.
On 30 Mar 2015, at 19:57, Kamil ÖZDEN <kamil.ozden.me@gmail.com <mailto:kamil.ozden.me@gmail.com>> wrote:
Dear All,
In a stenosed pipe flow problem, I specify parabolic velocity profile u=2*(1−(r^2)), where r=sqrt(y^2+z^2) as seen below.
/*<BOUNDARYREGIONS>*//* *//* <B ID="0"> C[7] </B> <!-- Inlet -->*//* *//* <B ID="1"> C[9] </B> <!-- Outlet -->*//* *//* <B ID="2"> C[8] </B> <!-- Wall -->*//* *//* </BOUNDARYREGIONS>*//* *//* *//* <BOUNDARYCONDITIONS>*//* *//* <REGION REF="0">*//* *//* <D VAR="u" VALUE="2*(1-(rad(y,z)^2))" />*//* *//* <D VAR="v" VALUE="0" />*//* *//* <D VAR="w" VALUE="0" />*//* *//* <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" />*//* *//* </REGION>*//* *//* <REGION REF="1">*//* *//* <N VAR="u" VALUE="0" />*//* *//* <N VAR="v" VALUE="0" />*//* *//* <N VAR="w" VALUE="0" />*//* *//* <D VAR="p" VALUE="0" />*//* *//* </REGION>*//* *//* <REGION REF="2">*//* *//* <D VAR="u" VALUE="0" />*//* *//* <D VAR="v" VALUE="0" />*//* *//* <D VAR="w" VALUE="0" />*//* *//* <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" />*//* *//* </REGION>*//* *//* </BOUNDARYCONDITIONS>*//**/
However, since u=0 at wall of the pipe due to no slip boundary condition definition, the calculated value of parabolic velocity profile at the wall (u = 1.5 ) can not be achieved. Is there any way to overcome this problem?
Regards, Kamil _______________________________________________ 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
participants (2)
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Kamil ÖZDEN
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Sherwin, Spencer J