On Wed, May 15, 2013 at 11:58 AM, Manav Bhatia <[email protected]> wrote: > > 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.
(I doubt stabilization is actually causing the p-convergence problems you're seeing, but just to clarify what I was getting at...) You plotted dNi/d(\xi) for these reference elements, where by "\xi" I mean the reference domain coordinate. But to compute the dNi/dx which is actually used in your formula, you have to multiply dNi/d(\xi) by the inverse jacobian, e.g. dNi/dx = dNi/d(\xi) * d(\xi)/dx For example: in 1D, a linear Lagrange element has Jacobian dx/d(\xi) = h/2, inverse d(\xi)/dx = 2/h, and therefore dNi/dx = (2/h) * dNi/d(\xi) which is O(1/h). -- John ------------------------------------------------------------------------------ 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
