Search found 72 matches

by Captain Slow
03 Nov 2011, 18:49
Forum: General
Topic: Relaxation factor
Replies: 2
Views: 3100

Relaxation factor

Howdy,

My qualitative understanding about the relaxation factor is that it essentially averages a quantity (say, velocity in N-S equation) over more than one step. As such it suppresses circulation/vortices in N-S such that convergence can be achieved more easily.

Is that correct?

John
by Captain Slow
26 Oct 2011, 18:09
Forum: External tools
Topic: gmsh mesh manipulations with small lengths
Replies: 3
Views: 5043

Re: gmsh mesh manipulations with small lengths

I've now found the solution to my original question. The points created in gmsh are saved as 3 co-ordinates plus a fourth for the characteristic length (set to 1e+22 by default), it seems that to get the box field to work correctly the ''Vout'' of the box section must match the characteristic length...
by Captain Slow
19 Oct 2011, 19:36
Forum: External tools
Topic: gmsh mesh manipulations with small lengths
Replies: 3
Views: 5043

gmsh mesh manipulations with small lengths

Hi all, I use gmsh to produce the meshes I use in elmer. I am currently trying to obtain a very small, 10^-6 or less, characteristic length (with box or boundary layer fields) in a specific area of the mesh. I have managed to control specific areas of the mesh with the box field for test cases of la...
by Captain Slow
12 Jul 2011, 20:43
Forum: ElmerSolver
Topic: limit on number of entries in savescalars file
Replies: 2
Views: 1974

Re: limit on number of entries in savescalars file

No-one?

I was hoping it would be a simple thing for people that are more familiar with the code of elmer to point me in the direction of solving?
by Captain Slow
06 Jul 2011, 16:08
Forum: ElmerSolver
Topic: limit on number of entries in savescalars file
Replies: 2
Views: 1974

limit on number of entries in savescalars file

Hi, I'm using Solver 2 Exec Solver = After All Equation = Fluidic Force Procedure = "FluidicForce" "ForceCompute" Calculate Viscous Force = True End Solver 3 Exec Solver = After All Procedure = "SaveData" "SaveScalars" Filename = fluidicforceNWh150_75leveldx8d...
by Captain Slow
24 May 2011, 15:03
Forum: ElmerSolver
Topic: Convergence of elasticity solver
Replies: 6
Views: 3587

Re: Convergence of elasticity solver

Further, the mesh file for the above geometry is attached
by Captain Slow
23 May 2011, 15:21
Forum: ElmerSolver
Topic: Convergence of elasticity solver
Replies: 6
Views: 3587

Re: Convergence of elasticity solver

Sorry, I didnt want to overload with information. Attached is the sif file and below is the mesh file. The fluid is flowing in through the channel on the right(BC 2 in sif file). The long, thin cantilever structure (BC 5) is the only thing that may move, and the fluid may flow out of the top, bottom...
by Captain Slow
20 May 2011, 15:58
Forum: ElmerSolver
Topic: Convergence of elasticity solver
Replies: 6
Views: 3587

Re: Convergence of elasticity solver

Thanks Peter, I already have a nonlinear relaxation factor of 0.1, have tried higher and it seems to be of little help. Timesteps are '1' so I cannot go any lower as it would be non-integer. I dont really want to go down the route of artificial compressibility as I'm really after confirming how the ...
by Captain Slow
20 May 2011, 14:16
Forum: ElmerSolver
Topic: Convergence of elasticity solver
Replies: 6
Views: 3587

Convergence of elasticity solver

I am working on an extension of the tutorial ''fluid flow around an elastic beam'', which I have replicated and achieved swift convergence. However, in my geometry I'm really struggling to get any convergence of the elasticity solver. As you can see below, the Navier Stokes solver converges, allowin...
by Captain Slow
08 Apr 2011, 12:19
Forum: ElmerSolver
Topic: elmersolver crashes
Replies: 6
Views: 5161

Re: elmersolver crashes

If youre using gmsh to construct the mesh I have found that you need to be very careful about not having a point that isnt part of a line, line that doesnt form part of the surface etc. Furthermore, there is problem with gmsh itself in that if the file becomes too big it crashes when meshing. It can...