Search found 177 matches

by spacedout
22 Feb 2024, 06:04
Forum: ElmerSolver
Topic: lagrangian element selection
Replies: 7
Views: 159

Re: lagrangian element selection

Thank you both for the detailed replies. There are indeed a lot of articles, books, and courses that deal with these isoparametric elements. Fortunately, my mesh elements have only straight edges. It is very refined around a curved airfoil so that I don't think it matters if it follows the curved ar...
by spacedout
19 Feb 2024, 01:36
Forum: ElmerSolver
Topic: lagrangian element selection
Replies: 7
Views: 159

Re: lagrangian element selection

Actually, what spurred my post was an article entitled Fluid Modelling of Dielectric Barrier Discharges for Plasma Technology by Jovanovic et al. Their research uses Comsol and in a given domain, they have linear Lagrange elements for continuity equations and quadratic Lagrange elements for the Pois...
by spacedout
15 Feb 2024, 00:37
Forum: ElmerSolver
Topic: lagrangian element selection
Replies: 7
Views: 159

lagrangian element selection

Hi Let's say I have a given triangular mesh (generated by Gmesh and transformed by ElmerGrid into the ElmerSolver format) How do I setup a given solver in the SIF to use linear Lagrange elements and another one to use quadratic Lagrange elements ? Also how would I tell a solver to use discontinuous ...
by spacedout
28 Jan 2024, 07:00
Forum: ElmerSolver
Topic: upwind or central difference scheme ?
Replies: 1
Views: 262

upwind or central difference scheme ?

Good evening The finite volume method usually use upwind scheme for convection terms and central difference scheme for diffusion terms. I know that the finite element method adopted the same idea since the late 1970s. I was curious to know if the same is true of the Elmer software because I don't se...
by spacedout
17 Jan 2024, 23:48
Forum: ElmerSolver
Topic: operator splitting and time integration schemes
Replies: 1
Views: 234

Re: operator splitting and time integration schemes

I got astronomical overflows after only 3e-8 sec for explicit euler and after only 6.5e-8 sec for implicit euler

I guess Elmer doesn't like my 3 ion continuity equations
by spacedout
16 Jan 2024, 06:05
Forum: ElmerSolver
Topic: operator splitting and time integration schemes
Replies: 1
Views: 234

operator splitting and time integration schemes

Good evening

If I decompose a PDE into a sequence of

dF/dt = some homogeneous term
dF/dt = some reaction term

should I use an an implicit or explicit time discretization scheme for each of these simplified PDEs ?

Best to all
by spacedout
16 Jan 2024, 03:02
Forum: General
Topic: Time discretization schemes
Replies: 7
Views: 4000

Re: Time discretization schemes

I found out that

you keep write

Timestepping Method = runge-kutta

inside a solver section

but there are implicit Runge Kutta methods. I am not sure if the default is explicit in Elmer. Also I wanted to set it to lowest order - just a simple Euler iteration.
by spacedout
14 Jan 2024, 18:04
Forum: General
Topic: Time discretization schemes
Replies: 7
Views: 4000

Re: Time discretization schemes

Hello
I know Crank Nicholson is half explicit and half implicit. BDF first order is fully implicit.
So what keyword setting should I use in a solver section to make its time integration fully explicit ?
Thanks
by spacedout
09 Jan 2024, 20:16
Forum: ElmerSolver
Topic: My advice on computational speed
Replies: 8
Views: 1047

Re: My advice on computational speed

Maybe I have not recovered from the cold yet. Not thinking straight - forgot to supply the mesh. Here it is attached with the previously reported code. Frankly, not sure what you mean by Hardcoded constant value , "Equals" and F90. In the end, I don't think I will use GetElementNodesVec. T...
by spacedout
08 Jan 2024, 00:37
Forum: ElmerSolver
Topic: My advice on computational speed
Replies: 8
Views: 1047

Re: My advice on computational speed

Hello in the following very simple test, the handles are initialized only once. Just compile SoSimpleTest and run the two SIFs. You will observe from the output of CheckTimer that the material coefficient reading a field variable using Real MATC "tx(0)" yields a time value that is about 40...