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

Mach contour expansion wave wrong

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 24, 2020, 10:20
Default Mach contour expansion wave wrong
  #1
New Member
 
Join Date: May 2020
Posts: 23
Rep Power: 2
CFDger is on a distinguished road
Hello,


I am simulating the hypersonic flow around a 2d wedge at M=8. So far the solution converges but it seems as if Fluent doen't display/calculate the expansion wave at the end of the wedge correctly. What I expect is a rise of the Mach number behind the expansion wave, this doesn't happen, at least that's my interpretation of the contour plot. Maybe this is due to the influence of the for high Mach numbers typical wake space behind the geometry?



I have heard that Ansys CFX can have problems regarding this topic but I haven't heard anything similar for Ansys Fluent.



Has somebody experience on this and/or can give me a hint where the source of my problem may be?


Thank you very much!
Attached Images
File Type: png Mach_contour_wedge_Ma_8.PNG (60.6 KB, 9 views)
CFDger is offline   Reply With Quote

Old   June 24, 2020, 16:15
Default Mach Contour
  #2
Senior Member
 
vinerm's Avatar
 
Vinerm
Join Date: Jun 2009
Location: Nederland
Posts: 2,948
Blog Entries: 1
Rep Power: 32
vinerm will become famous soon enough
Do you have any comparable work from the literature? The contours don't look at they should; not just at the wake but even upstream. Do you have fine enough mesh? Which numerical schemes have you used? And are you modeling it as inviscid or viscous flow?
__________________
Regards,
Vinerm

PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.
vinerm is offline   Reply With Quote

Old   June 24, 2020, 16:26
Default
  #3
New Member
 
Join Date: May 2020
Posts: 23
Rep Power: 2
CFDger is on a distinguished road
Hi vinerm,
thanks for your reply.

I have to mention that this is a wedge with a small radius at the tip.

Fluent Settings:
Density based
implicit
Roe-FDS
2. Order Upwind
Geen Gauß node based
viscous flow, k-w-sst

I have around 300000 cells and I have refined the mesh near the geometry. I also implemented a y+<1.
I have comparable simulation data for sharp wedges only.
That's interesting, I thought that at least everything upstream to the expansion wave was correct.

Does this information help you on judging this case?

Thanks
CFDger is offline   Reply With Quote

Old   June 30, 2020, 03:47
Question
  #4
New Member
 
Join Date: May 2020
Posts: 23
Rep Power: 2
CFDger is on a distinguished road
Does somebody else have an opinion/idea for solving this problem?


Thank you very much.
CFDger is offline   Reply With Quote

Old   June 30, 2020, 05:53
Default
  #5
Roh
Senior Member
 
Join Date: Sep 2017
Posts: 135
Rep Power: 5
Roh is on a distinguished road
The result should be something like this, right?(but without reflecting surface):





Source of the image:


https://www.sciencedirect.com/scienc...0093611930336X





Have you changed the legend? e.g. between 3-6 Mach ?


What about the schlieren image?
Roh is offline   Reply With Quote

Reply

Tags
compressible flow, expansion wave, fluent, hypersonic, wedge

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
udf error srihari FLUENT 1 October 31, 2016 14:18
Rapid expansion of Helium: wrong behavior in regards to Joule-Thomson effect antb OpenFOAM Running, Solving & CFD 1 June 25, 2014 11:06
wrong contour of pressure at the ailfoil leading edge s.m OpenFOAM Running, Solving & CFD 21 August 1, 2013 11:15
Wrong wave generation nuovodna OpenFOAM 2 August 9, 2010 10:53
Pressure contour seems wrong??? Harry Qiu FLUENT 1 June 29, 2001 05:53


All times are GMT -4. The time now is 23:39.