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Unexpected unit of input

Posted Feb 19, 2020, 11:06 a.m. EST Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD), Parameters, Variables, & Functions 1 Reply

Reza Danesh
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Hi everyone,

I want to create a function for Cp of a material and for a simple function, COMSOL gives me "unexpected unit of input"!

260-300 (K) 9.797*T-1029

300-340 (K) 3247-8.861*T+1.821*10^(-2)*T^2

the unit for the argument is in K and for Cp J/(kg*K).

Did anyone know how can I solve this problem?

Thank you in advance,

1 Reply Last Post Feb 19, 2020, 11:24 a.m. EST
Dave Greve
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Posted: 5 years ago Feb 19, 2020, 11:24 a.m. EST
Updated: 5 years ago Feb 20, 2020, 1:04 a.m. EST

Presumably you got the expression for Cp from a reference somewhere. Is the Cp in that reference J/(kgK)? Are you sure T is in K? You need to be very careful using empirical expressions.

IF the units are the same, then write

3247*J/(kgK)

-8.861T*J/(kgK*K)

etc.

Presumably you got the expression for Cp from a reference somewhere. Is the Cp in that reference J/(kgK)? Are you sure T is in K? You need to be very careful using empirical expressions. IF the units are the same, then write 3247\*J/(kgK) -8.861T\*J/(kgK\*K) etc.

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