Computation window explained

[bthrossell]

Hi,

Running a sub-grid 2D only model. Looking for some further information on what the computations window is showing me. The screenshot shows me that I am on Iteration (2D) 23? But my max iterations is set (“unsteady computation options and tolerances”) to 20, what am I missing?

The computations window also shows the WS eleavtion error for a given cell. Is this the error at which point HEC gave up an moved onto the next timestep? Also, what do the convergance numbers in the computation window refer to? I thought it would be the iterations required to converge on a solution?

Am I correct in thinking the computation windows should be read as follows:
Convergance represents the average number of iterations taken to find the best solution and this is the water elevation error of the best solution (at the named cell)?

Thanks for any guidance.

[Jarvus]

When it gets to the maximum iterations, I know it can do one more iteration as part of the volume convergence. But I am not sure why it is going to 23.

If the time step doesn’t converge, the WS error is the error for that given cell when it went on to the next the next time step. Although technically, I think it is a volume error that gets converted to an approximate WS error because WS error makes more sense to users.

The convergence numbers are discussed in the 2D user manual. It has something to do with whether the answers are getting better or worse on the final iteration. You can look it up. I have never found it useful.

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