effect of time_shrink_factor on a growing fire

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Thushadh Wijesekere

Jan 25, 2023, 7:16:13 AMJan 25
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I want to visualize some results very quickly.

Is it ok to use the time_shrink_factor for a case with a growing fire with a ramp. there are no water droplets (sprinklers etc) in the simulation.

Please let me know.



Jan 25, 2023, 7:48:06 AMJan 25
to FDS and Smokeview Discussions
The FDS User's guide states:

6.2.3 Special Topic: Steady-State Applications

Occasionally, there are applications in which only the steady-state solution (in a time-averaged sense) is
desired. However, the time necessary to heat the walls to steady-state can make the cost of the calculation
prohibitive. In these situations, if you specify a TIME_SHRINK_FACTOR of, say, 10, the specific heats of
the various materials is reduced by a factor of 10, speeding up the heating of these materials roughly by 10.

TIME_SHRINK_FACTOR doesn't make the entire simulation faster, it just lets solid materials heat up faster which means that if you have a scenario where you just care about steady-state results you can reduce the time it takes for a steady, in-depth, wall temperature profile to devevlop. In your case, however, you have described a scenario that is not a steady-state scenario.

Thushadh Wijesekere

Jan 25, 2023, 7:55:02 AMJan 25
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yes - I get it. It is definetely not a steady state case at the begining but it eventually becomes one. I just wanted to know whether this could at least approximate the smoke flow in the transient phase without any astronomical errors.

Thanks for the information.

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