Hi
I decided to use Modelpde.F90 as a template for both the Poisson and the continuity equations in my plasma research. Now, from an earlier post on June 1 2021 concerning Modelpde , I was told Stabilize is not available but that Bubble stabilization is. However because I get
ERROR:: ElementInfo: Bubbles for element: 706 are not implemented
as I reported on Nov 11 2021, I decided not to use Bubbles.
Which means that both keywords Stabilize and Bubbles are then set to False.
Is there a risk that the computation could turn out to be nonsensical as is stated for example in the ElmerModels manual under the keyword section of the Advection-Diffusion equation ?
Best regards
Modelpde with no stabilization
Re: Modelpde with no stabilization
It should be possible to apply bubble augmentation by giving a p-element definition. For example
Element = "p:1 b:1"
creates one elementwise bubble function. This construct doesn't depend on the keyword Bubbles and needs the background mesh consisting of the lowest-order elements.
--Mika
Element = "p:1 b:1"
creates one elementwise bubble function. This construct doesn't depend on the keyword Bubbles and needs the background mesh consisting of the lowest-order elements.
--Mika
Re: Modelpde with no stabilization
Section E.1 of the Elmer Solver manual displays a table giving the number of DOFs as a function of the local polynomial degree p for various elements and for nodes, edges, faces and bubbles. On the other hand,
Element = "n:N'
Element = "e:E'
Element = "f:F'
Element = "b:B'
are allowed under section G.1 which means the number of DOFs is now chosen arbitrarily and is thus independent of p.
I just don't get it. Therefore, I started to read Solin's textbook entitled Higher-order finite element methods. Hopefully all of this will then become clearer.
Element = "n:N'
Element = "e:E'
Element = "f:F'
Element = "b:B'
are allowed under section G.1 which means the number of DOFs is now chosen arbitrarily and is thus independent of p.
I just don't get it. Therefore, I started to read Solin's textbook entitled Higher-order finite element methods. Hopefully all of this will then become clearer.
Re: Modelpde with no stabilization
In Elmer the basic element definition for using the p-version of FEM is just "p:k", where k defines the order of approximation. Elmer then assigns automatically the right numbers of DOFs associated with different geometric entities (edges, faces and element interiors). Mixing the definition "p:k" with "e:E" or "f:F" is not allowed, but exceptionally the number of elementwise bubble functions can be adjusted by the user, so the form "p:k b:B" works. The documentation can be used to check how many bubbles come with a certain polynomial order.
The definitions of types "e:E" or "f:F have been applied to create (vector-valued) finite elements which give either tangential or normal continuity. Then the suitable basis functions are returned by special subroutines (EdgeElementInfo or FaceElementInfo).
The definitions of types "e:E" or "f:F have been applied to create (vector-valued) finite elements which give either tangential or normal continuity. Then the suitable basis functions are returned by special subroutines (EdgeElementInfo or FaceElementInfo).