Turbulent kinetic energy spatial transport

In whichever approach, the common denominator of most operations in stirred vessels is the common notion that the rate e of dissipation of turbulent kinetic energy is a reliable measure for the effect of the turbulent-flow characteristics on the operations of interest such as carrying out chemical reactions, suspending solids, or dispersing bubbles. As this e may be conceived as a concentration of a passive tracer, i.e., in terms of W/kg rather than of m2/s3, the spatial variations in e may be calculated by means of a usual transport equation. 

The second class of techniques is based on the description of spatial and temporal variations of turbulent intensity (or kinetic energy) by a transport equation. Essentially, one regards Km and Ke as being governed by a transport equation which describes the convection, diffusion, creation, and destruction of the turbulence. This approach has been pioneered by Daly and Harlow (68), Harlow and Nakayama (69), and Bradshaw et al. (70). 

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