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Find location of a minimum

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Hi,

I am still in the beginner phase with COMSOL and thus have some basic questions regarding the post processing. After the simulationI want to creat a few own "performance coefficients" that need to be programmed. If I am not mistaken this can be achieved via model couplings and I am thus currently exploring those.
Eventually I would like to automate the entire post processing procedure.
The first task sounds very easy but I have not found the right way to do it yet: I want to analayse a quantity along a boundary (lets say the shear stress) and find the position and value of all the local minima.

If those of you who have more experience with these model couplings could share theire knowledge on this, I would be very thankful.

Regards,
Franz

3 Replies Last Post 2010年6月26日 GMT-4 10:09
Daniel Smith COMSOL Employee

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Posted: 1 decade ago 2010年6月25日 GMT-4 12:29
Dear Franz, you can use the model coupling to do this. So, to find the minimum stress you would define a minimum model coupling on the boundary of interest then use:

minop1(solid.mises) for the minimum stress
minop1(solid.mises,x) for the x-location of the minimum stress
minop1(solid.mises,y) for the y-location of the minimum stress
minop1(solid.mises,z) for the z-location of the minimum stress

The attached model modifies the wrench model in the model library and computes these values. They are defined under the Derived values node and the numeric values appear in the Results table.
Dear Franz, you can use the model coupling to do this. So, to find the minimum stress you would define a minimum model coupling on the boundary of interest then use: minop1(solid.mises) for the minimum stress minop1(solid.mises,x) for the x-location of the minimum stress minop1(solid.mises,y) for the y-location of the minimum stress minop1(solid.mises,z) for the z-location of the minimum stress The attached model modifies the wrench model in the model library and computes these values. They are defined under the Derived values node and the numeric values appear in the Results table.


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Posted: 1 decade ago 2010年6月25日 GMT-4 13:43
Thank you very much Daniel, that helped a lot.

But this function, of course, can only determine the local minimum on a boundary. Is there also a way to extend this to local minima if there were several on a single boundary?

Franz
Thank you very much Daniel, that helped a lot. But this function, of course, can only determine the local minimum on a boundary. Is there also a way to extend this to local minima if there were several on a single boundary? Franz

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年6月26日 GMT-4 10:09
Hi
I would try to scan the boundary by some bolean operator to limit the x,y z or r extend, but you must do i "by hand", or the 3.5 way export it back to matlab and write your own algorithm

Good luck
Ivar
Hi I would try to scan the boundary by some bolean operator to limit the x,y z or r extend, but you must do i "by hand", or the 3.5 way export it back to matlab and write your own algorithm Good luck Ivar

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