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-   -   kinetic energy of rotating fluid flow (http://www.cfd-online.com/Forums/main/107853-kinetic-energy-rotating-fluid-flow.html)

abbie October 8, 2012 05:49

kinetic energy of rotating fluid flow
 
Dear all,

For a rotating rigid body which is translating at the same time, the total kinetic energy= translation energy (1/2*mass*velocity^2)+rotational energy (1/2*moment of inertia*vorticity^2).

However, would like to ask - for fluid flow which is rotating (such as vortex) and translating simultaneously, does the total kinetic energy=translation energy (1/2*density*velocity^2)+rotational energy (1/2*radius*vorticity^2)??

Thanks!:)

michujo October 8, 2012 06:20

Hi Abbie. No, the kinetic energy of the fluid particles is entirely accounted for in the first term of your equation (1/2*density*velocity^2), because the velocity vector includes the longitudinal and the tangential component. Otherwise you would be accounting for the rotation of the fluid to the kinetic energy twice.

Cheers,
Michujo.


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