CFD Online Discussion Forums - Axisymmetric nozzle design using the MOC

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)

- Main CFD Forum (https://www.cfd-online.com/Forums/main/)

- - Axisymmetric nozzle design using the MOC (https://www.cfd-online.com/Forums/main/6073-axisymmetric-nozzle-design-using-moc.html)

2D Axisymmetric MOC code

Hi guys,

I have the location for quasi 2D Diverging nozzle:
http://www.mathworks.com/matlabcentr...-nozzle-design

I am looking for a code that handles an axisymmetric nozzle. First, I tried modifying this code and got it to work by changing how the area to circular sections. It, runs but the nozzle does not make sense. Does anyone have any ideas or have a good robust code that works.

Thanks

my e-mail is sahay@umich.edu

Dear Vivek Ahuja,

I have no idea if you are still around here, since the initial posts are long time ago.
Anyway, I am kindly asking if you'd share the code with me too. The output of your sample screenshot is looking awesome!

I was starting to learn programming (Python), bought several books, was reading through loads of papers and was always left frustrated by facing the same problems as you described ...

Quote:

Originally Posted by Vivek Ahuja (Post 267840)

Also, Anderson's explanation for the axi-symmetric case in his book only describes the basic equation derivations. How to numerically integrate that equation (using finite difference schemes) and also to apply in the initial and necessary boundary conditions as well as the concept of the undefined region and its difference with the Prandtl-Meyer expansion system of 2D systems is not discussed. Frankly speaking, that left me thoroughly disappointed since we had to eventually develop that theory independently.

While there are some better sources on 2D MOC nozzles, sufficient guidance on 3D cases seem to be matter of a secret science.

I'd be more than happy if you could prevent me from going nuts. :o
nozzlefan@online.de

Thanks

cron

Looking for qualified freelancer to simulate supersonic flow through C-D nozzle using fluent 6.2.16

please contact upal_arif@yahoo.com

Quote:

Originally Posted by Vivek Ahuja (Post 267840)

Based on some prior experience writing MOC software codes for a NASA short course material, I can vouch for thet fact that the design of 3D nozzles with MOC is a very different kettle of fish as compared to the 2D model from a computational and theoretical standpoint. The problem remains with the "undefined" region between the throat line and the first Mach line for axi-symmetric cases. This is of course not "undefined" in the case of 2D flows thanks to the Prandtl-Meyer equations and hence the initialization of flows is defined along the first sonic line characteristic for 2D flow and using reflection techniques for the centerline calculations.

For 3D flow, thanks to the undefined region, the computation must start from the centerline with a specified pressure distribution along that axis and must move radially outwards. The problem remains in the hit-and-trail methodology that must be used to get the proper characteristic solution for the 3D flow case with such a relatively intuitive and therefore probably unrealistic initial condition.

Also, Anderson's explanation for the axi-symmetric case in his book only describes the basic equation derivations. How to numerically integrate that equation (using finite difference schemes) and also to apply in the initial and necessary boundary conditions as well as the concept of the undefined region and its difference with the Prandtl-Meyer expansion system of 2D systems is not discussed. Frankly speaking, that left me thoroughly disappointed since we had to eventually develop that theory independently.

I would be very interested to be able to discuss our efforts with any members here who have worked on the 3D MOC problem as well.

Regards