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Evaluate standard deviation of element size h
Posted 26.10.2020, 09:45 GMT-4 General, Mesh, Results & Visualization Version 5.5 2 Replies
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I consider a 3D model with a free tetrahedral mesh. I calculate the average of the element size h via "Derive Values" --> "Volume average". This part works. Now I would like to calculate the standard deviation of the element size, but I couldn't find out how to use the expression correctly. Comsol has already provided the template which I found via "add expressions":
stddev(op, expr) -> Standard deviation of op(expr, ...)
The first argument of stddev() has to be a string due to diverse error messages I got. Does anyone know what I need to write instead of "op"? Thank you for your help.
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The first argument to stddev() should be the name of an operator.
Some ways to achieve what you want:
Add a Nonlocal Coupling intop1 of type Integration to Component > Definitions, update the solution, and evaluate stddev('comp1.intop1',h) in a Global Evaluation.
Add a Nonlocal Coupling aveop1 of type Average to Component > Definitions, update the solution, and evaluate sqrt(aveop1((h-aveop1(h))^2)) in a Global Evaluation.
See https://www.comsol.com/forum/thread/40335/standard-deviation-over-a-data-set for a longer explanation.
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Thank you for your answer! Both ways work for my problem!