Planar Laser-Induced Fluorescence Method for Analysis of Mixing in Laminar Flows

Abstract

We report a laser-induced fluorescence (LIF) experimental method that is able to quantify dye concentration in a laminar three-dimensional flow. The geometry of interest is a stirred tank reactor agitated by three impellers. The method is employed to reveal the spatial structure of the evolving mixing patterns and its statistical properties. For chaotic flow conditions, the statistics of the passive scalar reveals a non-Gaussian concentration probability density function with an exponential tail. We find that the concentration patterns, once established, do not change with time; i.e., they are self-similar. This LIF method also provides detailed flow structures that are of importance to the study of mixing. Flow structure varies considerably as a function of Reynolds number (Re). However, we find that the mixing patterns are structurally invariant and they slowly decay as a result of a nonequilibrium state between stretching and diffusion.

On the mixing characteristics of a poorly water soluble drug through microfluidic‐assisted nanoprecipitation: Experimental and numerical study

“…The main principle of the LASP process has been widely reported in detail . The final product quality of precipitation processes is often determined by the interplay between mixing and relevant phenomena such as nucleation, molecular growth, aggregation, and breakage …”

“…[9][10][11] The final product quality of precipitation processes is often determined by the interplay between mixing and relevant phenomena such as nucleation, molecular growth, aggregation, and breakage. [12,13] Due to the great potential applications of microfluidic systems in intensification of liquid-liquid mixing performance, the synthesis of organic materials by microfluidic techniques has been increased in biomedical and pharmaceutical engineering domains. [14][15][16] Specifically, small dimensions of microfluidic devices confine the formation of vortices by restriction of the flow, so the solution in micro-flow systems generates a laminar flow pattern.…”

Reciprocating flow-based centrifugal microfluidics mixer

“…Such standard deviation is commonly referred as a mixing index. 13,31,44 Standard deviation or mixing index, as herein defined, is the deviation of the light intensity in the mixing chamber from the mean value of the intensity over its entire area. A lower value of the standard deviation indicates a more homogenous mixture and a higher mixing efficiency.…”

“…43,44 As deployed, the PLIF system consisted of a high resolution charge coupled device ͑CCD͒ camera ͑PowerView 11MP, ucts from Thermo Fischer Scientific, Freemont, CA͒. The particles contain embedded fluorescence dye within the polystyrene matrix, with an excitation maximum at 542 nm and an emission maximum at 612 nm, with a refractive index of 1.59 and a suspension density of 1.06 g / cm 3 .…”

Theoretical and experimental study of resonance of blobs in porous media

“…PLIF was introduced in late 1970s and has been used to examine many types of flow, including flow in porous media (Dewey, 1976;Owen, 1976;Liu et al, 1977;Dimotakis et al, 1983;Montemagno and Gray, 1995;Rashidi et al, 1996;Crimaldi and Koseff, 2001;Pan and Meng, 2001;Fontenot and Vigil, 2002;Shiono and Feng, 2003;Stöhr et al, 2003;Webster et al, 2003;Arratia and Muzzio, 2004;Matsumoto et al, 2005;Troy and Koseff, 2005;Onishi and Komori, 2006;Ovdat and Berkowitz, 2006;Hsu et al, 2012). PLIF allows us to acquire undistorted cross-sectional images of blobs in complex porous media at a high temporal resolution.…”