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November 28, 2024 at 2:51 am
Nick Fan
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November 28, 2024 at 10:59 am
Rob
Forum ModeratorHow far off the maximum timestep limit are you? It may also be a safety factor to avoid exceeding the value, there's likely some detail in the Theory Guide.Â
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December 3, 2024 at 1:48 am
Nick Fan
Subscriber-
December 3, 2024 at 1:57 pm
Rob
Forum ModeratorIf you're hitting the maximum time step 1s, then Courant Number limit may not be reached.Â
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December 4, 2024 at 2:22 pm
Nick Fan
SubscriberThank you for your reply, Rob. To clarify, should I first calculate the time step size that satisfies my desired Courant number based on my settings? Is it recommended to use a value larger than this calculated time step size as my "maximum time step size"?
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December 4, 2024 at 2:27 pm
Rob
Forum ModeratorI use adaptive stepping very rarely as you risk fast transients forcing the solver to the minimum value or stability issues if the time step oscillates between two values because of a relatively fast transient.Â
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December 5, 2024 at 2:33 am
Nick Fan
SubscriberThank you for taking the time to respond, Rob.Â
If I want to set the time step size based on the Courant number, is there a way to calculate the desired time step size using Fluent's functionalities? -
December 5, 2024 at 1:58 pm
Rob
Forum ModeratorNot really as you don't know the flow velocity before starting the calculation.Â
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December 9, 2024 at 6:51 am
Nick Fan
SubscriberThanks for your reply, Rob.
So, when I start a simulation, should I first use the adaptive type method to determine the timestep size that satisfies my Courant number, and then use this timestep size with the fixed type method to complete my subsequent simulation? -
December 9, 2024 at 11:47 am
Rob
Forum ModeratorI tend to estimate a likely highest speed, work out how long that takes to cross a cell and divide that number by 10. That's my starting time step. I then adjust (carefully) from there. It's fairly rough rule of thumb we've been using for over two decades and usually works.Â
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December 11, 2024 at 9:03 am
Nick Fan
SubscriberThank you for your valuable suggestions, Rob.
I will consider your advice in the upcoming simulations.
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November 28, 2024 at 6:30 pm
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December 3, 2024 at 1:49 am
Nick Fan
SubscriberThanks for your valuable information, Federico.Â
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