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-   -   Estimating 3d run time from 2d run time. (http://www.cfd-online.com/Forums/main/16332-estimating-3d-run-time-2d-run-time.html)

Sam February 10, 2009 11:23

Estimating 3d run time from 2d run time.
 
Hi Folks:

Let us say I have a 2d case that takes x sec/cell/iteration to execute, based on bench marked tests. Is it a reasonable assumption that a 3d case will take the same amount of time ? Thanks for your answers.

Sam

pc February 10, 2009 12:23

Re: Estimating 3d run time from 2d run time.
 
Your 3D case presumably will have one additional equation to solve (W-momentum), right? If so then no, the 3D case will be more expensive per cell per iteration.

otd February 10, 2009 13:42

Re: Estimating 3d run time from 2d run time.
 
Your parameter is the correct one to look at. By the way, that was defined as the "grind time" by the T-3 group at Los Alamos in the late 60's. [At least, that's the only place I ever heard it used.]

Another factor to consider is that (for a transient problem at least), the stability limit on the time step will probably shrink as the third dimension is added.


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