Not only due to its versatility and inexpensive availability, lab-on-a-chip integrates multitasks for a complete µTAS. Due to easy portability in micro-devices, microfluidics has potential to revolutionize in many applications that include food, pharmaceutical, biomedical and chemical industries, etc. Mixing is inevitable for the analysis of trace chemicals, drugs, bio-molecules, fluidic controls in microfluidics, etc. Such miniaturized microfluidics had already proven better over bulky instrumentations, because of time and transportation required in handling.
In this work, both active and passive were computationally studied. Passive mixing is considered with the mass fraction at different velocities of various mixer models when the fluids are in contact with each other. A two dimensional comparative analysis was performed to see the degree of mixing on two standard geometries including T and Y for general purposes. Along with standard geometries including T & Y, combinatory models with more than two inlet ports were also investigated using ANSYS Fluent, finite volume software. The engulfment flow was the major reason responsible for the mixing process. The engulfment flow was one of the major reasons responsible for the mixing process. Diffusion is a dominant phenomenon in passive mixing at the junction where various inlets meet and convective process becomes prevalent. Identification of geometrical correlation with the flow field variables and mixing parameters are crucial for better mixing design. The active mixing would be mathematically modeled with additional body force in the momentum equation. Thus, active mixers are externally activated for better mixing possibilities than the time consuming and possible complex geometries in passive mixing.
Concentration variances over time at the outlet were simultaneously compared in all models for mixing. Also average concentration was tracked over time so as to confirm uniformity in mixing. Active circular mixers were observed to work effectively with four electrode pairs at frequency of 8 Hz and potential of 0.1 volt. Parametric analysis on various geometries, mixing obstacles and electrode positions in the mixing zone showed that circular mixer with converging inlet and diverging outlet promises for better mixing efficiency and effectiveness.