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unknown unit error in COMSOL4.0

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hi, everyone!
I am a COMSOL4.0 beginner. I simulated a simple 2D-piezoelectric SAW modal. It 's a reatangle in attachment file. Its boundary conditions consisted periodic boundary on two sides and fixed constraint on bottom. When I used m, cm, mm units system, it could work , only many warnings, 'The relative residual is greater than the relative tolerance. Relative residual 8.5e-014 Relative error 1e+002' . However, when i used um unit system, a error occured, 'Unknown unit - Unit: ?m'.

Locate the Geometry Settings section. Find the Units subsection. From the Length unit list, select µm

Thanks for consideration, any help is appreciated.


1 Reply Last Post Dec 1, 2010, 3:04 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Dec 1, 2010, 3:04 a.m. EST
Hi

there are several weakness in V4.0 concerning default solver settings used, so there are a few fileds to tewak, often the results are still usable even with these warnings. I can only suggest to call your rep and get hands on the latest 4.1 version, the handling of these solver issues are greatly improved

--
Good luck
Ivar
Hi there are several weakness in V4.0 concerning default solver settings used, so there are a few fileds to tewak, often the results are still usable even with these warnings. I can only suggest to call your rep and get hands on the latest 4.1 version, the handling of these solver issues are greatly improved -- Good luck Ivar

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