Mathematical analysis of mixing index for 3D-helical micromixture with rectangular cross-section by providing convergent divergent profile

Abstract

The sole purpose of this research is to simulate and examine the characteristics of mixing and pressure drop inside a 3D helical micromixer with a convergent-divergent profile and having rectangular cross-section. A passive micromixer only requires flow-driven energy, unlike an active micromixer which requires flows driven as well as mixing energy. Mixing inside a simple passive micromixer mainly depends on the mass diffusion process, which is time-consuming and requires an elongated microchannel length. So, it becomes requisite to design a micromixer that enhances mixing as well as reduces the prolonged length. For the proposed micromixer, before running the actual simulations, the computational method used in this study was tested against earlier work, and the results demonstrate good agreement with those found in the literature. Using the Continuity and Navier–Stokes equations with water as the working fluid, a thorough numerical examination of mixing performance and fluid flow patterns was carried out at the outlet and five different cross-sections inside the microchannel with a wide range of Reynolds numbers from 2 to 260. The mixing index of the C-D Tdhm is 10% higher at Re = 260, and the pressure drop is almost 40% lower when compared to simple Tdhm mainly because of secondary flow and formation of separation and dean vortices. According to the numerical analysis presented in this paper, the C-D Tdhm delivers superior results at the same mixing length compared to simple Tdhm for all Reynolds number values evaluated in the study. Therefore, C-D 3D helical micromixer can be used in a variety of biological, electrical, biomedical, and Microtech applications.