Abstract: A plain, circular, high speed rotor, completely covering, and spaced apart from, the end of a thin walled stationary cylinder, forms a short narrow high shear gap. The cylindrical chamber allows fluid axially approaching the central rotor surface to be accelerated radially, to higher speeds over most of the plain rotor, to pass directly through the short shear gap near the rotor periphery. The higher speed fluid in the rotor boundary layer entering the gap excludes free stream turbulence from the high shear region. By adjustments of the gap clearance, one unit with an inch diameter stationary cylinder can dissolve, grind, prepare submicron dispersions, emulsify, mix or pump fluid mixtures at more than three gallons per minute. The gap clearance limits the size of particles passing through the gap without grinding and the force opposing gap spreading controls the intensity of grinding. After grinding is completed the elastic gap may close to the adjusted gap clearance.