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

Turbulent Separation problem

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 5, 2015, 07:19
Default Turbulent Separation problem
  #1
Member
 
mike
Join Date: Jun 2011
Posts: 42
Rep Power: 12
fluidmechanics is on a distinguished road
Dear all

I am modeling laminar separation bubble over NACA0012 at Re=1.35E5. The airfoil experiences different A.O.A in a 2D problem (It is a static run). Yplus is round 1 and 4Eq. kwSST transition modeling ( Gamma and Theta) is used. I can capture separation bubble and reattachment and transition to turbulent flow. I have some questions which have confused me:

1- Why is it possible to capture separation bubble with steady solver, while as we know separation is a time dependent phenomenon?

2- What might be the reason that I can not capture trailing edge turbulent separation with both steady and unsteady solvers at AOA 6, 8 and 10 degree while experiments report turbulent separation point at x/c = 0.9, 0.8, 0.6!!!

I have also tried some fully turbulent flows using K-w SST with yplus=1, but no turbulent separation is observed in rather high A.O.A (X-wall shear flux does not vanish)!!

Experiment results are based on " An Experimental Investigation of Flow Over an Oscillating Airfoil" a MSC thesis 2004 at McGill University, Montreal, Quebec, Canada.

I have attached some contour and plots. Any comment or tutorial on how to capture separation point? Any idea?!

Regards
Attached Images
File Type: jpg BL MESH.jpg (167.9 KB, 10 views)
File Type: jpg MESH-AOA 8 deg.jpg (166.5 KB, 10 views)
File Type: jpg yplus.jpg (51.1 KB, 11 views)
File Type: jpg StreamLine3.jpg (55.5 KB, 14 views)
fluidmechanics is offline   Reply With Quote

Old   September 7, 2015, 13:59
Default Any idea about separation
  #2
Member
 
mike
Join Date: Jun 2011
Posts: 42
Rep Power: 12
fluidmechanics is on a distinguished road
Any Idea of CFD experts about my separation problem recently posted?

Trivial ,but strange!!!!!!!!!!!!:
fluidmechanics is offline   Reply With Quote

Reply

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
Use of k-epsilon and k-omega Models Jade M Main CFD Forum 39 March 19, 2020 18:27
turbulent heat transfer problem ~ ztdep FLUENT 1 May 22, 2014 07:56
how to define turbulent intensity in 2d problem blueberry FLUENT 1 March 13, 2013 09:09
Problem in modeling membrane gas separation hakim22 FLUENT 0 July 31, 2011 10:28
Problem of Turbulent Viscosity Ratio Limited David Yang FLUENT 3 June 3, 2002 06:13


All times are GMT -4. The time now is 16:01.