Ponentes
Descripción
Magnetic recovery of functionalized particles from liquid flows is relevant to water treatment, environmental remediation, biomedical processing, and microfluidic separation. The design of these systems requires a consistent description of the competition among fluid advection, magnetophoretic drift, gravitational settling, diffusion, particle inertia, and, at finite particle loading, feedback of the dispersed phase on the carrier flow. This work presents a hierarchical Lagrangian–Eulerian framework for the numerical analysis of magnetic-particle capture in a two-dimensional laminar channel subjected to a nonuniform magnetic field generated by an external regularized line dipole.
The hierarchy connects four levels of description: an inertialess one-way trajectory model, a separatrix-based estimate of recovery efficiency, a conservative Eulerian advection–diffusion equation for particle concentration, and a two-way coupled mixture model derived from a reduced Maxey–Riley equation. The formulation is organized in terms of the Reynolds, Péclet, Stokes, Froude, and Mason numbers, together with the density ratio and a particle-loading parameter. The equations are solved with a stabilized finite-element method using Taylor–Hood interpolation for the carrier flow, residual-based stabilization for particle transport, backward-Euler time integration, and a monolithic Newton scheme.
Numerical results show a transition from flow-dominated transport at large Mason number to strong wall capture when magnetic drift becomes comparable to or greater than hydrodynamic advection. In the high-Péclet limit, the inlet position of the capture separatrix provides an inexpensive estimate of recovery efficiency. The Eulerian model resolves finite-diffusion effects and the spatial distribution of wall-deposition flux. For the magnetic configuration considered, the drift field is locally expansive over the particle-transport region; therefore, stronger capture is associated primarily with increased wall-directed flux rather than necessarily with local concentration amplification. Two-way coupled simulations further indicate that sufficiently large particle loading and magnetic forcing can alter the carrier-flow pressure response through momentum transfer from the magnetically driven particle phase.
The proposed framework provides a unified basis for predicting recovery efficiency, deposition location, and hydrodynamic response in magnetic separation devices, with potential applications in contaminant removal, environmental remediation, and biomedical particle handling.
Keywords: magnetophoresis; magnetic particle recovery; particulate flow; Lagrangian–Eulerian modeling; finite-element method; environmental remediation.