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Help for Inconsistent units, thanks
Posted May 29, 2012, 9:16 a.m. EDT Version 4.2a 2 Replies
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Hi, excuse me,
I am trying to define a repeating laser scanning mechanism (or multiple passes scan) in COMSOL 4.2a, and just met a problem of "Inconsistent units" when defining an effective laser intensity q_eff as if(t[1/s]<8,q_laser1[(m^2)/W],if(t[1/s]<16,q_laser2[(m^2)/W],0)).
q_laser1 and q_laser2 are laser intensity with top hat beam shape for scanning pass 1 and 2, respectively. The scanning mechanism is suggested as repeating the scan with a constant traverse speed, and each scanning time is defined as 8 seconds.
It seems like the dimensionless problem, could anyone please offer any suggestions? Really thanks!
Best regards,
Liwei
I am trying to define a repeating laser scanning mechanism (or multiple passes scan) in COMSOL 4.2a, and just met a problem of "Inconsistent units" when defining an effective laser intensity q_eff as if(t[1/s]<8,q_laser1[(m^2)/W],if(t[1/s]<16,q_laser2[(m^2)/W],0)).
q_laser1 and q_laser2 are laser intensity with top hat beam shape for scanning pass 1 and 2, respectively. The scanning mechanism is suggested as repeating the scan with a constant traverse speed, and each scanning time is defined as 8 seconds.
It seems like the dimensionless problem, could anyone please offer any suggestions? Really thanks!
Best regards,
Liwei
2 Replies Last Post May 30, 2012, 9:26 a.m. EDT
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Posted:
1 decade ago
Hi
if your variables "q_laser1 and q_laser2" already are defined with units they will "double" the units in the way you write it
But if these are defined as [W/m^2] they will arrive dimensionless, which is probably better for the "if(,,)" but then probably you need to multiply your full expression the results by 1*[W/m^2] to get back coherent units
Personally I prefer using step/rectangle functions but I do not see why your way should work
--
Good luck
Ivar
if your variables "q_laser1 and q_laser2" already are defined with units they will "double" the units in the way you write it
But if these are defined as [W/m^2] they will arrive dimensionless, which is probably better for the "if(,,)" but then probably you need to multiply your full expression the results by 1*[W/m^2] to get back coherent units
Personally I prefer using step/rectangle functions but I do not see why your way should work
--
Good luck
Ivar
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Posted:
1 decade ago
Hi Ivar,
Thank you very much for you reply, and I think building a step function would be a great idea, and I will try that shortly, thanks again!
Thank you very much for you reply, and I think building a step function would be a great idea, and I will try that shortly, thanks again!