CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > ANSYS Meshing & Geometry

prismatic layers

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 9, 2010, 07:02
Default prismatic layers
  #1
New Member
 
vinay
Join Date: Aug 2010
Location: bangalore,india
Posts: 6
Rep Power: 6
vinuaero@yahoo.co.in is on a distinguished road
hi,
can anyone tell me how prismatic layers are related with aerodynamic conditions like pressure,temperature,velocity etc.
vinuaero@yahoo.co.in is offline   Reply With Quote

Old   August 9, 2010, 10:49
Default
  #2
Senior Member
 
AB
Join Date: Sep 2009
Location: France
Posts: 323
Rep Power: 12
BrolY will become famous soon enough
The prismatic layers are created to capture the boundary layer.
The boundary layer depends on your aerodynamic conditions (The number Y+ is usually used to calcul the height of the boundary layer). The most important one is the velocity.
You can google it for more details about the Y+ formula.
BrolY is offline   Reply With Quote

Old   August 10, 2010, 00:28
Default
  #3
New Member
 
vinay
Join Date: Aug 2010
Location: bangalore,india
Posts: 6
Rep Power: 6
vinuaero@yahoo.co.in is on a distinguished road
Hi Alex,
I have got the formula to solve it.but i didn't understand the term "REF. LENGTH".please guide me.
Thank you,
vinuaero@yahoo.co.in is offline   Reply With Quote

Old   August 10, 2010, 04:41
Default
  #4
Senior Member
 
AB
Join Date: Sep 2009
Location: France
Posts: 323
Rep Power: 12
BrolY will become famous soon enough
The reference length depends on your geometry.
For example, if the geometry is a pipe, you would use the diameter (or the radius) as the reference length. Got it?
BrolY is offline   Reply With Quote

Old   August 10, 2010, 05:12
Default
  #5
New Member
 
vinay
Join Date: Aug 2010
Location: bangalore,india
Posts: 6
Rep Power: 6
vinuaero@yahoo.co.in is on a distinguished road
yes i got it.Do u know about KARMAN and upsweep discretization in ICEM CFD TETRA?
Please give some suggestions.
thank you,
vinuaero@yahoo.co.in is offline   Reply With Quote

Old   August 10, 2010, 05:52
Default
  #6
Senior Member
 
AB
Join Date: Sep 2009
Location: France
Posts: 323
Rep Power: 12
BrolY will become famous soon enough
I'm sorry, I can't help you on that. Maybe someone else on the forum?
Good luck !
BrolY is offline   Reply With Quote

Old   August 10, 2010, 15:48
Default
  #7
Senior Member
 
PSYMN's Avatar
 
Simon Pereira
Join Date: Mar 2009
Location: Ann Arbor, MI
Posts: 2,662
Blog Entries: 1
Rep Power: 35
PSYMN has a spectacular aura aboutPSYMN has a spectacular aura about
vinuaero you may be putting too much pre-thought into it...

Basically, you just want your prism layer to be thicker than your boundary layer so you can more efficiently capture the boundary layer profile.

Run your Y+ Calcs, etc. (they are useful for the first cell height) but at some point you just need to put as many prism layers on there as you can and send it to the solver. Then look at the solution with the grid visible.

Is the majority of the boundary layer (slower flow) within the prisms? If so, is it relatively close or are your prisms much thicker than they needed to be (did you put excess work and sacrifice quality to get prisms you didn't need...? Learn for next time.) Does it look like your prisms are not thick enough to capture the viscous boundary layer profile?

Most CFD analysts are really repeat users (repeat offenders) who learn from previous runs and generate better meshes based on understanding a certain class of problem. You probably won't know exactly how thick your prism layer should be until you make a few runs on that type of configuration and get a feel for it... Just make sure to observe how your results relate to your mesh and learn as you go. Most mature customer sites have meshing guidelines for various classes of models which they guard closely as trade secrets.

You may also want to run some mesh refinement studies to see if your mesh is fine enough that the results are not dependent on them.
PSYMN 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
SnappyHexMesh doesn't succeed in adding several layers eti0123456789 OpenFOAM Native Meshers: snappyHexMesh and Others 5 April 9, 2013 02:36
Boundary layers in Gambit Ian FLUENT 3 March 3, 2012 10:54
SST model and boundary layers Rodrigo Basniak CFX 7 March 27, 2008 15:19
Creating inflation layers for elbow with airfoil ! Aplus CFX 1 March 13, 2006 23:22
Effects of numbers of layers in the BL zones CFD Rookie Main CFD Forum 2 January 30, 2004 11:43


All times are GMT -4. The time now is 04:05.