Mixing in small scale fluidic systems swayed by rotationality effects

Abstract

In the present endeavor, we discuss the enhancement strategy of important fluidic functionality, i.e., mixing in an on-chip device embedded in a rotating disk both qualitatively as well as quantitatively. Our analysis, on accounting for the effect of rotation in the framework, uses a set of mechanically consistent classical fluid dynamic equations in describing the mixing of the constituent fluids comprehensively. Motivated by the need of benchmarking our modeling framework, we perform experiments in the limiting case of pure diffusion and show that suggestions from the experimental part of this endeavor verify the numerical results quite effectively. The results indicate that the effect of molecular diffusion and rotation-induced forcing non-trivially modulates the underlying mixing in the portable fluidic device. Of particular interest, we show that, even for weak molecular diffusion between the chosen fluid pair, strong advective transport of species as rendered by a higher rotational effect results in an enhanced mixing, that too achievable at short distances from the channel entry. Finally, a phase diagram mapping the mixing efficiency in the flow-fluid properties plane is provided, expected to be a design guideline for the portable fluidic systems/devices, typically used for mixing and diagnosis of bio-fluids.