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

boundary layer thickness

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 29, 2000, 01:39
Default boundary layer thickness
  #1
Lee,jangho
Guest
 
Posts: n/a
hi? i am graduate student in south Korea. i HAVE useD luent5.1 and solved NACA 00XX SERIES i want to mesured the boundary layer thickness at the trailing edge of airfoil. but i can find any display item about that. anyone who know any means write the answer to me thanks...
  Reply With Quote

Old   August 29, 2000, 03:52
Default Re: boundary layer thickness
  #2
John C. Chien
Guest
 
Posts: n/a
(1). I guess, you need to define the boundary layer thickness in the first place. (2). Once you have define that, you can use the computed results to derive the boundary layer thickness.
  Reply With Quote

Old   August 29, 2000, 13:56
Default Re: boundary layer thickness
  #3
Kai Kang
Guest
 
Posts: n/a
You can use the definition of bc layer thickness to define a scalar (under \DEFINE in Fluent) to represent the boundary layer's boundary. If that's not work, you might need to do a little own post-processing instead of clicking on Display...
  Reply With Quote

Old   September 24, 2000, 22:06
Default Re: boundary layer thickness
  #4
Lee,jangho
Guest
 
Posts: n/a
thank for replaying to everyone. but i can't understand actually if you have more time , please write more detail. thanks...
  Reply With Quote

Old   September 25, 2000, 00:09
Default Re: boundary layer thickness
  #5
John C. Chien
Guest
 
Posts: n/a
(1). At the location where you want to compute the boundary layer thickness, say just befor the trailing edge, you can display the velocity profile from the wall to the outer boundary . (2). For the flow over the airfoil, you should have two boundary layers, one on the top (the suction side), and the other on the bottom (the pressure side). (3). If you define the edge of the boundary layer as the location where the velocity is 99.5% of the local free stream velocity value, then you can calculate the location of the edge of the boundary layer.(measured from the wall) So, at the trailing edge location (a straight line) you need to define the local free stream velocity.(this is when the velocity is uniform. It may not be easy if the flow is somewhat non-uniform, but, the boundary layer concept is derived based on the uniform local free stream concept.) (4). Whether it should be 99.5% or 99.9% , it is up to you, as long as it is used consistently. (5). So, draw the velocity profile along the trailing edge location from the wall to the free stream or outer boundary. Draw a parallel line to the local free stream velocity at the 99.5% value. The location where the profile value is 99.5% of the local free stream velocity is the edge of the boundary layer. The boundary layer thickness is : the thickness measured from the (trailing edge) wall to the edge of the boundary layer. (6). By the way, if you don't have enough number of mesh points inside the boundary, it is going to be difficult to find the location of the edge of the boundary layer accurately.
  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
boundary layer thickness Ralf Schmidt Main CFD Forum 5 April 24, 2010 11:50
Boundary layer thickness ghazanfarzahedi Main CFD Forum 2 July 28, 2009 23:43
Boundary layer thickness calculation nat FLUENT 0 April 9, 2009 06:04
plotting boundary layer thickness graphs in a 3d Neelima FLUENT 1 March 29, 2006 18:04
Boundary Layer Thickness cfd-freak Main CFD Forum 3 March 27, 2003 13:18


All times are GMT -4. The time now is 21:23.