|
[Sponsors] |
May 5, 2003, 09:59 |
Time Step Restriction
|
#1 |
Guest
Posts: n/a
|
Dear Freinds,
In recent days I am studing semi-implicit methods for calculating creep flows. In these methods, what are the time step restriction? Thanks. |
|
May 5, 2003, 12:06 |
Re: Time Step Restriction
|
#2 |
Guest
Posts: n/a
|
Actually there are no theoratical formulas to determine the time step restriction for the nonlinear differential equations. They are only available for linear PDEs. The rule of thumeb is to make the discretization as implicit as possible. Don't just throw all the nonlinear terms in the source term, you can linearize it and put the higher order truncation terms in the source term. The other qualitative rule is to reduce the time step whenever you reduce the spatial grid size, especially in the dominant flow direction.
|
|
May 6, 2003, 04:55 |
Re: Time Step Restriction
|
#3 |
Guest
Posts: n/a
|
1. diffusion term. 2. chemical source terms. 3. convective terms. For a unsteady computation, one better use implicit method of some kind for 1 and 2.
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
HELP! time step too small? | meangreen | Main CFD Forum | 6 | May 31, 2018 10:41 |
Velocity blows up suddenly after 30,000+ iterations | lordvon | OpenFOAM Running, Solving & CFD | 15 | October 19, 2015 13:52 |
convergence problem when use pisoFoam, LES for wind tunnel case | Forrest_Lei | OpenFOAM | 3 | July 19, 2011 06:00 |
Full pipe 3D using icoFoam | cyberbrain | OpenFOAM | 4 | March 16, 2011 09:20 |
Intermediate step during a time step | Burn | OpenFOAM | 0 | July 16, 2009 10:01 |