|
[Sponsors] |
deciding time duration in transient simultion |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
March 3, 2012, 08:43 |
deciding time duration in transient simultion
|
#1 |
New Member
Join Date: Jan 2012
Posts: 9
Rep Power: 14 |
I am doing a transient simulation for my model ,
I have decided to use time steps as 0.0632 seconds,how do I decide the time duration ?I first gave time duration as 65 and time steps as 0.0632 but the solver ran continously ..has'nt converged at all |
|
March 4, 2012, 04:05 |
|
#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,703
Rep Power: 143 |
How have you decided 0.0632s is the right time step size? If it is not converging it probably is not the right size.
And as for the time duration - what are you modelling? An inkjet printer ejection (total time about 10 microseconds), or magma motion in a magma chamber (turn over time 140 million years). I have done work in both and guess what? They both use different total simulation times. |
|
March 4, 2012, 06:17 |
|
#3 |
New Member
Join Date: Jan 2012
Posts: 9
Rep Power: 14 |
I am modelling the flow of air through the intake manifold of a 4cyl diesel engine ,naturally aspirated ,upto before valve..now I calculated timestep by taking the whole length of manifold as distance and inlet velocity of air , that value I took multiplied by (1/20) to get 0.0632 sec ..my length is 0.349 m and intake velocity is 27.61m/s ..1/20 because that is the time required for a particle of fluid to traverse the length of object
|
|
March 4, 2012, 16:41 |
|
#4 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,703
Rep Power: 143 |
Hmmm, I don't think you have much idea of how to set a time step
My PhD thesis was on IC engine modelling. Have a look at the time step size I used: http://hdl.handle.net/2100/248 |
|
March 5, 2012, 07:47 |
|
#5 |
New Member
Join Date: Jan 2012
Posts: 9
Rep Power: 14 |
Thanks for that thesis..i have got new doubts...how is the CFL stability criterion related to timestep..and I am not able
to comprehend what a timestep is and what are the parameters that affect it. |
|
March 5, 2012, 17:16 |
|
#6 | ||
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,703
Rep Power: 143 |
Quote:
Quote:
|
|||
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Superlinear speedup in OpenFOAM 13 | msrinath80 | OpenFOAM Running, Solving & CFD | 18 | March 3, 2015 05:36 |
Upgraded from Karmic Koala 9.10 to Lucid Lynx10.04.3 | bookie56 | OpenFOAM Installation | 8 | August 13, 2011 04:03 |
Transient Time Step for supersonic flows | CP | CFX | 1 | November 12, 2007 16:22 |
Modeling in micron scale using icoFoam | m9819348 | OpenFOAM Running, Solving & CFD | 7 | October 27, 2007 00:36 |
unsteady calcs in FLUENT | Sanjay Padhiar | Main CFD Forum | 1 | March 31, 1999 12:32 |