  The micromixing time of impinging thin liquid sheets depends upon the energy
dissipation rate. The kinetic energy released by the impingement has been
previously studied and was found to be a function of the coefficient of
restitution of the collision. In this work, the volume within which the
released kinetic energy is dissipated was investigated. The volume of energy
dissipation was determined by measuring the time required for the velocity of
the single sheet (prior to the collision) to be reduced to the velocity in the
mixed sheet (after the collision). Although different, the velocity in single
sheets and the velocity in mixed sheets has been previously shown to be
constant. High-speed video was used to measure the velocity of features,
generated in the front single sheet, as they passed through the impingement
zone and into the mixed sheet. The experimental results showed that the time
required for the velocity change was approximately equal to the residence time
of liquid in the impingement zone. A new equation for the energy dissipation
rate was developed and compared with the energy dissipation rate derived from
turbulence energy-cascade theory. This comparison showed that the large-eddy
turnover time was approximately equal to the residence time in the impingement
zone; a result that is in accordance with the notion from turbulence
energy-cascade theory that large, energy-containing eddies lose their energy
within approximately one large-eddy turnover time. Within the impingement zone,
the large-eddy kinetic energy was found to decay exponentially with time.
