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Forum: OpenFOAM Running, Solving & CFD November 19, 2007, 12:49
Replies: 30
Views: 11,354
Posted By hjasak
Hello, Sunday, November 19,

Hello,

Sunday, November 19, 2006 - 06:37 am: almost exactly a year ago... You got me confused for a moment.

The reference I refer to came from Fluent News, 2004...
Forum: OpenFOAM Running, Solving & CFD November 19, 2006, 08:37
Replies: 30
Views: 11,354
Posted By hjasak
Well, my second PhD supervisor

Well, my second PhD supervisor at Imperial College was Raad Issa of the PISO fame. ;-) In any case, PISO is more efficient for cases where the time-step is determined by the need for temporal...
Forum: OpenFOAM Running, Solving & CFD November 19, 2006, 06:12
Replies: 30
Views: 11,354
Posted By hjasak
Hi Frank, The answer is: go

Hi Frank,

The answer is: go back to basics. First, you know that running transient SIMPLE will have no Courant number limit. Start with that, and first order discretisation in time - if you...
Forum: OpenFOAM Running, Solving & CFD November 18, 2006, 10:55
Replies: 30
Views: 11,354
Posted By hjasak
Why is Crank-Nicholson in Open

Ferziger, Peric, what page? Hirsch, what page? (cannot find it)

I have shown in my PhD that Crank-Nicolson is not unconditionally unstable (based on numerical diffusion) so what you say is...
Forum: OpenFOAM Running, Solving & CFD March 6, 2006, 06:12
Replies: 30
Views: 11,354
Posted By hjasak
You have several options. I s

You have several options. I suspect the problem you are getting is that the mesh deformation may become quite sensitive to the convergence of the motion solver. The issue is that you've got a...
Forum: OpenFOAM Running, Solving & CFD March 4, 2006, 15:22
Replies: 30
Views: 11,354
Posted By hjasak
I did the first 5 seconds and

I did the first 5 seconds and made a little animation for you (it is ugly but proves the point). The automatic time-step control is well-behaved and there's no problem with the simulation (I am...
Forum: OpenFOAM Running, Solving & CFD February 27, 2006, 17:50
Replies: 30
Views: 11,354
Posted By hjasak
Very easy: it does not work be

Very easy: it does not work because you've set the time step to give the Courant number of 3.5, which is jolly high. I have dropped the time step by a factor of 4 and with the Co number of around 1...
Forum: OpenFOAM Running, Solving & CFD February 24, 2006, 08:56
Replies: 30
Views: 11,354
Posted By hjasak
I'll have a look if you want.

I'll have a look if you want. Could you please pack the code (ready to run, if the mesh is made with blockMesh, please delete unnecessary files, with time-step, discretisation, initial fields etc...
Forum: OpenFOAM Running, Solving & CFD February 23, 2006, 09:29
Replies: 30
Views: 11,354
Posted By hjasak
motionU: you can do whatever y

motionU: you can do whatever you like, this is only used to specify the motion. Typically, if you wish to specify the motion of an object, you would use the fixedValue b.c. on its surface (makes...
Forum: OpenFOAM Running, Solving & CFD February 21, 2006, 11:10
Replies: 30
Views: 11,354
Posted By hjasak
The solver looks fine (well, a

The solver looks fine (well, at least not obviously wrong). However, your residual behaviour indicates a serious problem and my guess is that you have messed up the boundary conditions.

Note...
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