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Using sign and abs on variables
Posted 31.05.2011, 20:40 GMT-4 Parameters, Variables, & Functions, Structural Mechanics Version 4.1 1 Reply
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Hello,
I typed the following into a boundary condition:
-sign(solid.u_tX)*beta*(abs(solid.u_tX))^m
where beta and m are constants that I defined, and solid.u_tX is the x-velocity. However, when I tried to solve, COMSOL could ot find consistent initial values. If I remove the sign and abs functions (and set m = 1), then COMSOL will solve. Is there a way to get this to work with the sign and abs functions?
Thanks,
Henry
I typed the following into a boundary condition:
-sign(solid.u_tX)*beta*(abs(solid.u_tX))^m
where beta and m are constants that I defined, and solid.u_tX is the x-velocity. However, when I tried to solve, COMSOL could ot find consistent initial values. If I remove the sign and abs functions (and set m = 1), then COMSOL will solve. Is there a way to get this to work with the sign and abs functions?
Thanks,
Henry
1 Reply Last Post 01.06.2011, 00:46 GMT-4
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Posted:
1 decade ago
Hi
sign and abs functions are know to have discontinuities, perhaps if you check that you work inone 1 quadrant, or that you smoothen the transitions it would solve better
--
Good luck
Ivar
sign and abs functions are know to have discontinuities, perhaps if you check that you work inone 1 quadrant, or that you smoothen the transitions it would solve better
--
Good luck
Ivar