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

Boundary condition involving 2nd derivative of U

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 7, 2007, 14:12
Default I'm implementing a boundary co
  #1
Senior Member
 
Maka Mohu
Join Date: Mar 2009
Posts: 305
Rep Power: 18
maka is on a distinguished road
I'm implementing a boundary condition that requires the knowledge of 2nd derivative of a vector (or scalar) field. My questions is how to calculate a 2nd derivative (Laplacian of vector or scalar field) on fvPatchField<vector>?

(1) I know that one can get the patch value of a field, say U, using lookupPatchField<volvectorfield,>("U")

(2) then get the value of 1st cell center using: U.patchInternalField()

(3) but to calculate 2nd derivative one need access to the value of 2nd cell center (one level more deep than U.patchInternalField())

(4) this is need to be done without in the parallel version of OpenFOAM. I'm using V1.3.

Thanks.

Best regards,
Maka
maka is offline   Reply With Quote

Old   November 8, 2007, 16:04
Default Reformulate your b.c. to work
  #2
Senior Member
 
Mattijs Janssens
Join Date: Mar 2009
Posts: 1,419
Rep Power: 26
mattijs is on a distinguished road
Reformulate your b.c. to work in terms of cell centre value and cell centre gradient.

Have your toplevel maintain a gradient-of-U field which is consistent with U so you can look it up in your b.c.

Anything using extended addressing is pretty hard to parallelise at the patch level (what if your 2nd layer cell is on another processor)
mattijs is offline   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
boundary condition for derivative of velocity Daiga CFX 2 December 7, 2009 18:11
source energy involving temperature gradient isabel FLUENT 0 July 14, 2008 07:40
Problems involving interFoam and GCC 410 gschaider OpenFOAM Installation 1 July 30, 2006 20:58
Derivative and double-Derivative for steep functio Kali Sanjay Phoenics 1 March 27, 2006 08:51
how derivative at boundary set to zero? mehdi_a FLUENT 3 June 1, 2004 23:30


All times are GMT -4. The time now is 04:38.