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Ahmed kandil March 13, 2024 07:32

Ansys expression
 
Hello everyone
I'm trying to write an expression for inlet temp with time and this is my expression
0.016[S]*t^6-0.2703[S]*t^5+1.6363[S]*t^4-4.3126[S]*t^3+5.1111[S]*t^2-1.6118[S]*t+298.26[S]
but i get this error
All arguments should have the same dimensions as the first argument [kg^-1 m^-2 s^9 A^2] but argument 2 has dimensions of [kg^-1*m^-2*s^8*A^2]
how i can solve this problem

rohansharmafree March 13, 2024 11:13

You have to adjust the units for all components.
Hence you need adjust the units of each constant.
I am not sure what is this unit [S]

RavingRaven March 13, 2024 13:57

Hi Ahmed,

This thread belongs in the ANSYS Fluent forum, not the CFD freelancers forum.

That being said... Your problem seems to be your units. You mentioned you're specifying temperature, so if you're working with SI units then every term should be in Kelvin (K).

Your formula seems to be a polynomial with different exponents of time - the unit of each coefficient should be K*s^(-n) where n is the power of the temperature term it is being multiplied with and s is seconds. For example, 0.016 * t^6 - here, 0.016 should have units of K*s^(-6) as this will make that whole term equal Kelvin.

Ahmed kandil March 15, 2024 07:37

Hi RavingRaven
Thank you for your reply and i will do this..

Ahmed kandil March 15, 2024 07:39

Hi rohansharmafree
Thanks ...


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