CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > Siemens

Simulation of transonic flow over NACA0012 airfoil

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 3, 2006, 15:41
Default Simulation of transonic flow over NACA0012 airfoil
  #1
MSc Student
Guest
 
Posts: n/a
Hi Im trying to simulate a flow of Mach no. 0.8 and angle of attack of 1.25deg over a NACA0012 airfoil. I have some results from a paper for validation purposes. This is shown below. Shock waves can clearly be seen. http://serv4.imagehigh.com/view.php?...&path=/imgs///

In my results i dont see any shockwaves on the upper or lower surface. These are shown below. (the mach no. link doesnt work on its own for some reason please copy and paste the total link to see it please)

http://serv4.imagehigh.com/view.php?id=30449_Mach_No. Plot1&path=/imgs///

http://serv4.imagehigh.com/view.php?...&path=/imgs///

Ive set the density to ideal f(T,P) set the viscosity to use the sutherland equation and the rest of the material properties are default. Air is my working fluid. Temperature cal. is on and conservation is set to total enthalpy. And the turbulence model is k-epsilon/high reynolds number

The pressure reference cell number has been set to a cell right at the inlet and the pressure is 1.e+05 and the temp is 293k for the reference cell.

The mesh is shown below and has 26200 cells:

http://serv4.imagehigh.com/view.php?...&path=/imgs///

http://serv4.imagehigh.com/view.php?...&path=/imgs/// The inlet(red) and outlet(green) boundaries have two sides as shown above in order to simulate more than 1 angle of attack using the same mesh.

The outlet BC is left at default and the inlet boundary is defined as shown below in the pic.

http://serv4.imagehigh.com/view.php?...&path=/imgs///

Ive used MARS differencing schemes on all variables and my factors are set as shown below

http://serv4.imagehigh.com/view.php?...&path=/imgs///

Im not sure why Im not capturing shocks I clearly have mach numbers over the top of the airfoil greater than 1.2.

I have completed the tutorial 6 in the user guide where you capture shockwaves in supersonic flow. Although inviscid flow was used in that case. Can anyone help me please? Are there any tips anyone could give me. Thanks in advance.

  Reply With Quote

Old   August 8, 2006, 08:29
Default Re: Simulation of transonic flow over NACA0012 air
  #2
MSc Student
Guest
 
Posts: n/a
Just an update.

In all cases of my simulation I get the following warning in my .info file that confuses me:

Warning #001 fluid inflow detected at some outflow boundaries where mass fluxes are forced to zero if this condition persists, your results might be wrong. The outflow boundary might not be well specified or the grid might be too coarse near the outflow boundary.

I have an inlet and outlet boundary condition situation with this type of flow.

  Reply With Quote

Old   August 9, 2006, 14:49
Default Re: Simulation of transonic flow over NACA0012 air
  #3
Ben
Guest
 
Posts: n/a
Use a pressure instead of an outlet, unless you have very uniform outflow at a outlet boundary you always get stability and convergence problems. I never use them (well I used them at first a long time ago but gave up long since) if you must insist on using an outlet make sure it is a LOOOOONG way downstream. This is what the error is about too, as I say I cant stand the things, usefull as a chocolate tea pot they are!
  Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Compressible transonic airfoil RAE2822 simulation Stefano Siemens 9 June 21, 2006 11:47
Unsteady simulation on the flow around Naca0012 Peter Pan Zhang FLUENT 2 June 11, 2006 20:53
y+ for NACA0012 transonic simulations Oscar Arias Main CFD Forum 7 June 9, 2006 02:27
transonic airfoil in Fluent Luis FLUENT 4 December 1, 2003 06:34
how to create airfoil section for NACA0012? stone_gargoly Main CFD Forum 3 March 10, 2003 16:48


All times are GMT -4. The time now is 10:20.