Experimental Measurement of Mixing Lengths of Converging Particulate Flows in Microchannels

Laminar flow mixing remains an active area of research within the microfluidics community. Traditional mixing methods often rely upon turbulent flow for mixing which is generally not present on the micro-scale and so alternative approaches must be sought. In this work we investigate the potential for enhanced laminar mixing due to the addition of inert particles, of varying size and concentration, to converging flows of miscible fluids at a 3-way microchannel ‘Y’ junction. One inlet fluid is fluorescently-labeled to enable imaging of the converging fluid interface downstream of the junction. Using the techniques of fluorescent microscopic imaging and digital image analysis, the degree of mixing is quantified for varying flow states by the measurement of dye concentration (intensity) profiles at downstream locations. It is found that the addition of particulates to the flow does not noticeably enhance laminar mixing over that which would normally occur due to mass diffusion processes alone.