EXPERIMENTAL AND NUMERICAL CHARACTERIZATION OF VISCOUS-FLOW AND MIXING IN AN IMPINGING JET CONTACTOR

The laminar flow in an impinging jet contactor is examined as a first step toward the development of new technology for fast mixing of visco us fluids. The flow, velocity, and stretching fields in an impinging j et contactor are quantified for low Reynolds number flow using three-d imensional numerical simulations and particle image velocimetry measur ements. Computational and experimental velocity fields are in close ag reement, as quantified by the velocity probability density functions. Two steady-state flow regimes are found to exist: for jet Reynolds num bers (Re-j) < 10, the jets do not impinge and the velocity field scale s linearly with Reynolds number; for Re-j > 10, the jets begin to impi nge and recirculation regions form above and below the impingement poi nt. The magnitude of the rate-of-strain tensor is calculated as a func tion of Re. While areas of essentially zero stretching occupy most of the flow domain, very high rates of stretching occur at specific locat ions in the flow. The maximum and average rates of stretching in the c ontactor increase roughly linearly as a function of Reynolds number. M ixing simulations show that no mixing occurs for the steady flow in a symmetric-jet contactor. However, mixing is improved substantially by a slight modification of the impinging jet geometry that disrupts geom etric symmetry.