On Wed, May 15, 2013 at 1:17 PM, John Peterson <[email protected]> wrote:
> On Wed, May 15, 2013 at 6:36 AM, Manav Bhatia <[email protected]>
> wrote:
> >>
> >>
> >> One other thought: do you have some O(h) stabilization terms present?
> >> Then if you aren't refining the grid they don't get smaller...
> >>
> >
> >
> > There is a GLS stabilization term with the typical tau matrix. I have
> > experimented with different tau definitions, but get the same behavior.
> >
> > Essentially, almost all definitions in 1-D have the form
> >
> > (sum_{i=1,n_shape_funcs} | a dNi/dx | ) ^-1
> >
> > where N is the shape function and 'a' is the velocity. The numeric value
> of
> > this expression reduces as the polynomial order is increased.
>
> Really? The lowest order hierarchics are the Lagrange basis
> functions, and dNi/dx ~ 1/h is certainly true for those.
>
Hi John,
I have attached a pdf which plots the expression for a 2-noded and a
3-noded element using Lagrange interpolation functions. The element has
unit length. The 2-noded value is constant at 2 for the entire domain of
the element, while the 3-noded element shows a variation in the element
domain. It equals 2 at xi=0, but rises to about 8 on either end. Each
quadrature point uses the inverse of this function value.
This is my basis for stating that the the influence of higher
polynomial order is included, although I can't say if this is constraining
the order of convergence.
Manav
------------------------------------------------------------------------------
AlienVault Unified Security Management (USM) platform delivers complete
security visibility with the essential security capabilities. Easily and
efficiently configure, manage, and operate all of your security controls
from a single console and one unified framework. Download a free trial.
http://p.sf.net/sfu/alienvault_d2d
_______________________________________________
Libmesh-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/libmesh-users
