getting negative values for Nusselt number and htc?

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  • Last Post 20 June 2019
hamda posted this 26 May 2019

 Hi,

I wrote some expressions for Nu and htc and when I drew contours I got negative values for them. Here are my expressions

Myhtc=Wall Heat Flux/(T-780[K])
Nu=Myhtc*0.06[m]/0.31[W m^-1 K^-1]
But as it can be seen in the pic. I got negative values for Nu. Is there any problem related to the expressions?

Thanks in advance

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rwoolhou posted this 04 June 2019

Look through the expression and work out how a negative number can be derived. As a hint, plot the temperature on the surface. 

hamda posted this 19 June 2019

Dear Rwoolhou,

I did that but  I didn't get a negative value for T. Just for Nu this happens.

rwoolhou posted this 19 June 2019

So

      ( T-780[K] ) > 0 ?

hamda posted this 19 June 2019

So

      ( T-780[K] ) > 0 ?

Yes

rwoolhou posted this 20 June 2019

Can you plot wall heat flux? 

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