CFD Online Logo CFD Online URL
Home > Forums > General Forums > Main CFD Forum

2D Transonic Internal Flow

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   March 31, 2004, 15:51
Default 2D Transonic Internal Flow
Posts: n/a
Hi, I have recently developed a 2D Euler solver based on Jameson's Finite volume formulation with 2nd and 4th order aritificial dissipation.

To benchmark the accuracy of the code, I am trying to apply it to a transonic flow through a 2D converging-diverging nozzle. With this I can compare the results along the plane of symmetry with the quasi-1D analytical results from Shapiro, or any other place.

However, the results I obtain depend on the boundary conditions I use as follows:

1. I explictly set the exit boundary condition to a constant pressure - 1 BC specified, and remaining extrapolated. At the inlet I specify the total pressure and temperature, and calculate the inlet Mach number from isentropic relations - 3 BC specified, 1 extrapolated. In this case, the results I obtain are the closest to the analytical case - I get a Mach number of 1 at the throat.

2. I retain the constant pressure boundary condition at the exit. However, at the inlet I use the Reimann invariant boundary conditions, calculating R+ from pinf = p0, Tinf = T0 & uinf = 0. In this case I get a completely subsonic flow, with the throat Mach number nowhere near zero. In fact, the inlet pressure is much lower than that obtained in case 1.

3. Used the boundary conditions from Jameson's paper: a) inlet conditions based on non-reflecting BCs based on linear characteristics and, b) exit conditions specified using a mixed formulation of non-reflecting+fixed pressure (ref:Rudy & Strikwerda). The results I obtain are similar to 2 above.

Since 2 & 3 were based on non-reflecting BCs, I did see a marked acceleration of convergence. However, the converged values were markedly different from 1) above or the analytical solutions.

Any insights, experiences ?

Thanks. - Ramki

  Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Flow meter Design CD adapco Group Marketing Siemens 3 June 21, 2011 08:33
CFD calculation from transonic to supersonic flow lawmc FLUENT 1 April 6, 2010 02:47
Fluent or StarCD for Internal flow FVS Main CFD Forum 1 May 17, 2004 02:28
Inviscid Drag at subsonic, subcritical Mach # Axel Rohde Main CFD Forum 1 November 19, 2001 13:19
Star-CD for transonic flow John McArthur Siemens 2 April 26, 2001 09:36

All times are GMT -4. The time now is 16:36.