# How can I simulate a system in hours instead of seconds?

**URL:** <https://community.freefem.org/t/how-can-i-simulate-a-system-in-hours-instead-of-seconds/2615>\
**Category:** General Discussion\
**Created:** [July 18, 2023, 7:09pm UTC](https://community.freefem.org/t/how-can-i-simulate-a-system-in-hours-instead-of-seconds/2615 "2023-07-18T19:09:23Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![jna1g18](https://avatars.discourse-cdn.com/v4/letter/j/77aa72/32.png) [@jna1g18](https://community.freefem.org/u/jna1g18)\
**Post date:** [July 18, 2023, 7:09pm UTC](https://community.freefem.org/t/how-can-i-simulate-a-system-in-hours-instead-of-seconds/2615/1 "2023-07-18T19:09:23Z")

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Hi. This is quite a general question related to numerical methods. I have a transient model in which the unit of time is seconds, but I want to simulate the system over a number of hours. The problem is that my model requires quite a small timestep of dt=0.01s which means that to simulate the system for a period of just 5 seconds, my timeloop must have a length of 500 and this takes a particularly long time to solve (computation time on the scale of hours)! So, the time it would take to simulate the system over a number of hours would be impractically large.

How can I get over this issue? Could I just convert the time unit from seconds to hours by rewritting all model parameters in terms of hours; e.g. 1 meter/second becomes 3600 meters/hour? This way, I could have a timestep of dt=0.01hr. Many thanks!