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Erratum in the Model Library PDF file

Posted Jan 25, 2012, 2:36 p.m. EST Version 4.2a 3 Replies

Dao Trinh (COMSOL)
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Hello,

There are a few error in the Model Library PDF file. For example, in the "2D Heat Transfer Benchmark with Convective Cooling" in Heat Transfer Library, the thermal conductivity is written as 52 W/m.C but in the real Comsol mph file, the thermal conductivity is 52 W/m.K.

So please pay attention on the unit because 52 W/m.C and 52 W/m.K are totally different.
Another errata can be found in "Transient Axisymmetric Heat Transfer" in Heat Transfer Library. The model pdf file and the real mph file didn't use the same unit.

Best regards,
Dao Trinh

3 Replies Last Post Jan 26, 2012, 10:10 a.m. EST
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Jan 25, 2012, 2:49 p.m. EST
W/m.K and W/m.C are equivalent.
W/m.K and W/m.C are equivalent.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 25, 2012, 3:19 p.m. EST
Hi

you are correct that one should take care about the coherence in notation and use SI units all the way, but for the first point, since °C=K have the same scale both are equivalent.

I'm not saying that an absolute temperature in °C and in K are identical, there I agree there is an offset of 273.15[K] = 273.15[degC] but there are two ways we use T:

it is the absolute T and Delta_T = temperture differences.

A heat flux exchange "h[W/m^2/K] is expressed in temperature difference mode so there is formally no "difference" between °C and K for temperaure differences, only for absolute temperatures. There is a paragraphe, in the doc, on the discussion of Temperature and it's unit, if you look up (not sure in which doc it is ;)

Still I propose that you send a short mail to "support" so they can correct this in the next issue, it's better to be coherent, I agree :)

--
Good luck
Ivar
Hi you are correct that one should take care about the coherence in notation and use SI units all the way, but for the first point, since °C=K have the same scale both are equivalent. I'm not saying that an absolute temperature in °C and in K are identical, there I agree there is an offset of 273.15[K] = 273.15[degC] but there are two ways we use T: it is the absolute T and Delta_T = temperture differences. A heat flux exchange "h[W/m^2/K] is expressed in temperature difference mode so there is formally no "difference" between °C and K for temperaure differences, only for absolute temperatures. There is a paragraphe, in the doc, on the discussion of Temperature and it's unit, if you look up (not sure in which doc it is ;) Still I propose that you send a short mail to "support" so they can correct this in the next issue, it's better to be coherent, I agree :) -- Good luck Ivar
Dao Trinh (COMSOL)
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Posted: 1 decade ago Jan 26, 2012, 10:10 a.m. EST
Thank you for your coherent response Ivar.

Cheers,
Dao
Thank you for your coherent response Ivar. Cheers, Dao

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