Menu

Discussion Forum

New Discussion
Filtrer

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Derivative of Normal on a Surface

Posted 26 sept. 2013, 13:36 UTC−4 Fluid & Heat, Computational Fluid Dynamics (CFD), Geometry, Studies & Solvers Version 4.3a 1 Reply

John Austin
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hello. Any help would be greatly appreciated. I am trying to calculate the mean curvature on a boundary. To do this, I am trying to calculate the dot product of the surface gradient operator and the normal vector. Thus, I need to take derivates like d(nr,r). However, whenever I do this, I only get zeros. Does anyone know how to implement these derivatives?

Another question would be, how do you take the derivative of something with respect to arc length, such as dn/ds?

Thanks in advance!
John
1 Reply Last Post 31 mai 2015, 03:56 UTC−4
COMSOL Moderator

Hello John Austin

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Ling-Feng Lu
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 31 mai 2015, 03:56 UTC−4
I got an answer from COMSOL support. There is no direct way to implement derivative with respect to r or arc length s. You need to transform the derivative w.r.t x,y,z coordinates. E.g. dn/ds=tx*dn/dx+ty*dn/dy.
hope this help you
I got an answer from COMSOL support. There is no direct way to implement derivative with respect to r or arc length s. You need to transform the derivative w.r.t x,y,z coordinates. E.g. dn/ds=tx*dn/dx+ty*dn/dy. hope this help you

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content