Transonic flow over a bump

A.D.E · July 5, 2011, 07:33

Hi am looking to run a CFD case for transonic flow over a bump (using OpenFOAM) and I was wondering if anyone has any data for such a case experimental and/or numerical to validate my results!! Additionally does anyone know if an analytical solution exist??

Martin Hegedus · July 6, 2011, 19:07

An option,

http://turbmodels.larc.nasa.gov/bump.html

A.D.E · July 7, 2011, 10:38

Hi Martin,

Thank you for your reply and link. Your link is helpful but I am looking for something a bit more technical to better understand the Physics behind such flows.. Do you have anything else in mind such as a chapter from a book and/or a technical paper??

Thank you in advance for your consideration and time!!

Sincerely,
A.D.E

Martin Hegedus · July 7, 2011, 13:26

Ooops, sorry I messed up. The link I sent was for Mach=0.2. Hardly transonic. There is the axisymmetric CFL3D (cfl3d.larc.nasa.gov) test cases http://cfl3d.larc.nasa.gov/Cfl3dv6/c...s.html#axibump. It also has a reference to an AIAA paper ("An Investigation of Transonic Turbulent Boundary Layer Separation Generated on an Axisymmetric Flow Model," AIAA 79-1479, 1979). There is also the OVERFLOW bump comparison, http://people.nas.nasa.gov/~pulliam/...OWTO/bump.html. It doesn't give much detail, but the results look similar to CFL3D. So, the AIAA paper may be a good starting point.

From my personal past theory experience, the bump, 2d and axisymmetric, are associated with linear potential flow and shock-expansion theory. They are for zero angle of attack. And of course doesn't include boundary layers. There is also 2nd order shock-expansion. Other than that, I don't know of a relevant paper or chapter for theory. And I guess that will not work since you are interested in testing OpenFOAM at transonic speeds. And, as far as I know, an Euler or NS analytic solution does not exist.

What type of bump are you looking for and what would you like to test, in addition to transonic flow? Are you interested in Euler or NS? Are you interested in separation?

Also, as far as I understand and I'm not sure of the ins and outs of OpenFOAM, but OpenFOAM will not converge for the supersonic portions of the transonic flow since it is a non coupled method. To solve transonic flow, the equations should be coupled. If you are able to converge your residuals to machine zero, let me know.

A.D.E · July 8, 2011, 07:25

Thank you for the new links Martin. I am relatively new with OpenFOAM and I was involved in low speed aerodynamics since now. I therefore want to enhance my knowledge on high subsonic and transonic flows as well as to understand the limitations of OpenFOAM. At the moment I am not interested in separation.

If I manage to converge my residuals I will let you know.

Once again thank you for your consideration and time.

Sincerely ,

A.D.E

July 5, 2011, 07:33	Transonic flow over a bump	#1
A.D.E Member Join Date: Jul 2011 Posts: 42 Rep Power: 14	Hi am looking to run a CFD case for transonic flow over a bump (using OpenFOAM) and I was wondering if anyone has any data for such a case experimental and/or numerical to validate my results!! Additionally does anyone know if an analytical solution exist??

July 7, 2011, 13:26		#4
Martin Hegedus Senior Member Martin Hegedus Join Date: Feb 2011 Posts: 500 Rep Power: 19	Ooops, sorry I messed up. The link I sent was for Mach=0.2. Hardly transonic. There is the axisymmetric CFL3D (cfl3d.larc.nasa.gov) test cases http://cfl3d.larc.nasa.gov/Cfl3dv6/c...s.html#axibump. It also has a reference to an AIAA paper ("An Investigation of Transonic Turbulent Boundary Layer Separation Generated on an Axisymmetric Flow Model," AIAA 79-1479, 1979). There is also the OVERFLOW bump comparison, http://people.nas.nasa.gov/~pulliam/...OWTO/bump.html. It doesn't give much detail, but the results look similar to CFL3D. So, the AIAA paper may be a good starting point. From my personal past theory experience, the bump, 2d and axisymmetric, are associated with linear potential flow and shock-expansion theory. They are for zero angle of attack. And of course doesn't include boundary layers. There is also 2nd order shock-expansion. Other than that, I don't know of a relevant paper or chapter for theory. And I guess that will not work since you are interested in testing OpenFOAM at transonic speeds. And, as far as I know, an Euler or NS analytic solution does not exist. What type of bump are you looking for and what would you like to test, in addition to transonic flow? Are you interested in Euler or NS? Are you interested in separation? Also, as far as I understand and I'm not sure of the ins and outs of OpenFOAM, but OpenFOAM will not converge for the supersonic portions of the transonic flow since it is a non coupled method. To solve transonic flow, the equations should be coupled. If you are able to converge your residuals to machine zero, let me know. lpz456 likes this.

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July 6, 2011, 19:07		#2
Martin Hegedus Senior Member Martin Hegedus Join Date: Feb 2011 Posts: 500 Rep Power: 19	An option, http://turbmodels.larc.nasa.gov/bump.html

July 7, 2011, 10:38		#3
A.D.E Member Join Date: Jul 2011 Posts: 42 Rep Power: 14	Hi Martin, Thank you for your reply and link. Your link is helpful but I am looking for something a bit more technical to better understand the Physics behind such flows.. Do you have anything else in mind such as a chapter from a book and/or a technical paper?? Thank you in advance for your consideration and time!! Sincerely, A.D.E

July 8, 2011, 07:25		#5
A.D.E Member Join Date: Jul 2011 Posts: 42 Rep Power: 14	Thank you for the new links Martin. I am relatively new with OpenFOAM and I was involved in low speed aerodynamics since now. I therefore want to enhance my knowledge on high subsonic and transonic flows as well as to understand the limitations of OpenFOAM. At the moment I am not interested in separation. If I manage to converge my residuals I will let you know. Once again thank you for your consideration and time. Sincerely , A.D.E