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time steps in time dependent study
Posted 21 sept. 2014, 05:59 UTC−4 Studies & Solvers Version 4.4 1 Reply
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hi!
im simulating fluid flow in a pipe with transport of diluted species.
when i run a time dependent study i noticed that comsol does not keep the time steps constant and skips over large periods of time without providing any data.
it starts with small steps but very soon they turn into very large steps.
how can i keep the time steps constant for the entire run ?
thanks a-lot!
tal.
im simulating fluid flow in a pipe with transport of diluted species.
when i run a time dependent study i noticed that comsol does not keep the time steps constant and skips over large periods of time without providing any data.
it starts with small steps but very soon they turn into very large steps.
how can i keep the time steps constant for the entire run ?
thanks a-lot!
tal.
1 Reply Last Post 21 sept. 2014, 08:46 UTC−4
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Posted:
1 decade ago
Hi,
I don't really get what u meant by "skips over large periods of time without providing any data". If u key in for example "range(0,0.1,1)" in "time dependent step", COMSOL should give you the results of every 0.1s step, even though it might start with small steps but very soon they turn into very large steps as u said.
To set so as COMSOL keeps constant step while computing, you can try to change its time stepping. You 1st right click at your study and click on "show default solver". Then u go to "time dependent solver" and u will see time stepping, log, results while solving tabs and etc. Expand the "time stepping" tab and u will see a drop down list with BDF as default. Below the drop down list you will see initial stepping and maximum stepping. Change it as your wish should be fine then.
Good luck
CN
I don't really get what u meant by "skips over large periods of time without providing any data". If u key in for example "range(0,0.1,1)" in "time dependent step", COMSOL should give you the results of every 0.1s step, even though it might start with small steps but very soon they turn into very large steps as u said.
To set so as COMSOL keeps constant step while computing, you can try to change its time stepping. You 1st right click at your study and click on "show default solver". Then u go to "time dependent solver" and u will see time stepping, log, results while solving tabs and etc. Expand the "time stepping" tab and u will see a drop down list with BDF as default. Below the drop down list you will see initial stepping and maximum stepping. Change it as your wish should be fine then.
Good luck
CN