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 MC December 10, 2006 21:57

Rought estimation of dissipation energy

I am trying to estimate energy disspation and the corresponding heat enrgy from the large scale characteristics of turbulent flow. Especially, heat engergy from the fluid flow. I know exact calculation of it is almost impossible but, I need to estimate roughly.

Problem : Dissipation energy of flows in a moved large cube

Dimension : L*B*H = 50m * 40* 30m Filling ratio : 95% of the height

Large scale velocity u ~ 5m/s Dimensional scale L ~ 50m

So, turbulent dissipation rate epsilon ~ u^3/L = 2.5 (Joule/(kg*sec))

Effective Mass in a cube ~ 4250 ton (because upper part of the fluid in a cube would be excited)

Finally, total energy dissipation 1) m*epsilon ~ 4250 ton * 2.5 = 10625 kW

If this energy could be changed to the heat energy 2) Q=4250 ton * 9,540Kj/KgK * dT ~ 10625MW

temperature difference dT ~ 0.00026

But, I think the energy of 10625kW looks too much. So, please comment the above 1) and 2).