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Author Topic: Q_total is always zero  (Read 3001 times)

ankita

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Q_total is always zero
« on: December 30, 2013, 04:40:10 am »

Hi!
In thermal plot results Q_total is about to zero where as Q_rad, Q_conv and Q_cond are negative and why these are negative ? 
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ankita

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Re: Q_total is always zero
« Reply #1 on: January 01, 2014, 10:55:46 pm »

Can anyone please help me?
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Charlie Thornton

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Re: Q_total is always zero
« Reply #2 on: January 02, 2014, 10:32:01 am »

Are you able to share your model?
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ankita

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Re: Q_total is always zero
« Reply #3 on: January 03, 2014, 04:56:14 am »

Please see the attached burner.psm file
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Charlie Thornton

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Re: Q_total is always zero
« Reply #4 on: January 03, 2014, 02:01:23 pm »

Actually, the model isn't the issue. Sorry about that. Thank you for sending it along.

My understanding is that negative Q_ values indicate a decrease in enthalpy and positive values indicate an increase. Negative radiative (Q_RAD), convective (Q_CONV), and conductive (Q_COND) values indicate these phenomena are reducing the total energy while HRR is causing energy to increase. In the FDS User Guide, Chapter 16.9.1: "Heat Release Rate" identifies the individual terms in the transport equation that you are seeing in the output.

EDIT: I wanted to add that these terms describe a rate of change. The low or negative Q_TOTAL just means that the model is balanced or cooling rather than getting hotter and hotter (I think).
« Last Edit: January 03, 2014, 02:07:42 pm by Charlie Thornton »
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ankita

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Re: Q_total is always zero
« Reply #5 on: January 06, 2014, 04:29:50 am »

thanks for the reply :)
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