High-Fidelity CFD Analysis of Mixing Dynamics in Turbulent Micromixers for LNP fabrication

Efficient mixing is essential in lipid nanoparticle (LNP) fabrication, as it directly influences particle size, uniformity, and encapsulation quality. Fluid dynamics properties, such as turbulence kinetic energy, mixing uniformity and mixing time scale, in combination with the time scale of the nanoparticle assembly, affect the quality of the product. This study explores the flow and mixing dynamics in two turbulent micromixers commonly used for LNP production: the Multi-Inlet Vortex Mixer (MIVM) and the Confined Impinging Jet Mixer (CIJM). Simulations are performed using a residual-based variational multiscale (RBVMS) finite element method. The model solves the incompressible Navier–Stokes and advection–diffusion equations to capture the mixing of water and ethanol, two miscible fluids with different densities and viscosities. In this study, we explore how changing the mixer geometries, inlet flow rates, and fluid properties affects mixing performance in both MIVM and CIJ mixers. We will present velocity and concentration fields, turbulent kinetic energy, mixing index, and the residence time distribution. We will briefly touch on experimental validation of our results and how it supports mixer design for LNP production.