Experiments have been performed to assess the efficiency of mechanical mixers in destratifying water bodies. The effects of Reynolds number, physical scale, and Richardson number were all considered. The results demonstrated that the variation of mixing efficiency with Richardson number was well described by two different power-law regimes. At low Richardson numbers, the efficiency increased wi...

Sample mixing is difficult in microfluidic devices because of laminar flow. Micromixers are designed to ensure the optimal use of miniaturized devices. The present study aims to design a chaotic-advection-based passive micromixer with enhanced mixing efficiency. A serpentine-shaped microchannel with sinusoidal side walls was designed, and three cases, with amplitude to wavelength (A/λ) ratios o...

An upper bound on the mixing efficiency is derived for a passive scalar under the influence of advection and diffusion with a body source. For a given stirring velocity field, the mixing efficiency is measured in terms of an equivalent diffusivity, which is the molecular diffusivity that would be required to achieve the same level of fluctuations in the scalar concentration in the absence of st...

The mixing efficiency Rf (more formally referred to as the flux Richardson number) is a widely used parameter that is intended to provide a measure of the amount of turbulent kinetic energy (TKE) that is irreversibly converted to background potential energy as a result of turbulent mixing in a stably stratified fluid. In this paper, three different definitions of the mixing efficiency that are ...

Application of cavity ring down (CRD) spectrometry for measuring the optical properties of pure and mixed laboratory-generated aerosols is presented. The extinction coefficient (α ext), extinction cross section (σ ext) and extinction efficiency (Q ext) were measured for polystyrene spheres (PSS), ammonium sulphate ((NH 4) 2 (SO 4)), sodium 5 chloride (NaCl), glutaric acid (GA), and Rhodamine-59...

The dependence of mixing efficiency on time-varying forcing is studied by direct numerical simulation (DNS) of Kelvin–Helmholtz (KH) instability. Time-dependent forcing fields are designed to reproduce a wavelike oscillation by solving the equations of motion in a tilted coordinate frame and allowing the tilt angle to vary in time. Mixing efficiency Gc is defined as the ratio of potential energ...

1 Multiscale Modeling and Simulation, Department of Applied Mathematics, University of Twente, P.O. Box 217, 7500 AE Enschede, the Netherlands [email protected] Anisotropic Turbulence, Fluid Dynamics Laboratory, Eindhoven University of Technology, P.O. Box 513, 5300 MB Eindhoven, the Netherlands 2 Mathematics Department, Imperial College London, SW7 2AZ, London, UK [email protected] Com...