CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

Solving the 2D Euler over a circular bump FDMethod

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 11, 2003, 21:24
Default Solving the 2D Euler over a circular bump FDMethod
  #1
Tarek
Guest
 
Posts: n/a
I developed a code to solve the steady state Euler equations in a 2D channel with a straight upper wall and a 10% circular bump on the bottom wall. I am using a MacCormack scheme (predictor/corrector) to solve the Euler equations on a body fitted mesh. When I run the code, I experience problems at the inlet. The Mach# on the nodes following the inlet will start decreasing throughout the iterations and I think this is why the solution is divering. I am using non reflecting boundary conditions. The inlet conditions are Mach#=0.5, density=1, Pressur=1/gamma. I could not find what the problem and am desperate for solutions. Thanks
  Reply With Quote

Old   December 12, 2003, 12:41
Default Re: Solving the 2D Euler over a circular bump FDMe
  #2
vasanth allampalli
Guest
 
Posts: n/a
U have to be very careful at the inlet specially in your case when the mach no is less that one.You have to find all the characteristics for the governing equation and decide which characteristics should be set by u and which should be set by the code.Ask if you need more help on this
  Reply With Quote

Old   December 12, 2003, 22:27
Default Re: Solving the 2D Euler over a circular bump FDMe
  #3
Tarek
Guest
 
Posts: n/a
Thanks for the advice. I was able to solve the problem at the inlet. Now my problem is convergence. I can see oscillations on the mach profile for the bottom boundary. The oscillations start at two places: a bit downstream of the leading edge and a bit downstraem of the trailing edge. Basically where there is a sharp transition from low mach number to high mach number. My question is could this method be unstable for my problem, (even though I was told it is not) and what can be done to get stability. I tried refining the mesh which didn't work, and playing with the CFL number only delayed the divergence. I included a dissipation factor based on velocity only, that is added to my flux matrices F and G. This again did not work. I am stuck at this point and need some suggestions. Thanks in advance.
  Reply With Quote

Old   December 13, 2003, 22:13
Default Re: Solving the 2D Euler over a circular bump FDMe
  #4
vasanth
Guest
 
Posts: n/a
u seem to have non -physical waves running around which I think is related to boundary conditions .I will tell u if come accross something
  Reply With Quote

Old   May 7, 2011, 03:29
Default
  #5
New Member
 
m p
Join Date: Nov 2010
Posts: 15
Rep Power: 6
moein_joon27 is on a distinguished road
Can some body tell me what are the correct boundary conditions for this problem? I assume a satic pressure at outlet o that with isentropic relations I have the inlet total p. then we need 3 more in 2D .among them one is extrapolation which I use riemann invariant extrapolation,but what are the others when we have the inlet mach number?
moein_joon27 is offline   Reply With Quote

Reply

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
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
Upgraded from Karmic Koala 9.10 to Lucid Lynx10.04.3 bookie56 OpenFOAM Installation 8 August 13, 2011 04:03
Orifice Plate with a fully developed flow - Problems with convergence jonmec OpenFOAM Running, Solving & CFD 3 July 28, 2011 05:24
Differences between serial and parallel runs carsten OpenFOAM Bugs 11 September 12, 2008 11:16
Could anybody help me see this error and give help liugx212 OpenFOAM Running, Solving & CFD 3 January 4, 2006 19:07


All times are GMT -4. The time now is 02:32.