The overdamped dynamics of particles dragged by a parallel flow in a straight micro-channel in the presence of a transverse acoustophoretic force is investigated. Analytical solutions are presented in the case of plug, shear, or Poiseuille flow velocity profile. Two regimes of particle dynamics are observed, namely an early regime dominated by the local stream-wise velocity and a later regime gove

Deterministic lateral displacement provides a novel and efficient technique for sorting micrometer-sized particles based on particle size. It is grounded on the principle that the paths associated with particles of different diameters, entrained in flow streaming through a periodic lattice of obstacles, are characterized by different deflection angles with respect to the average direction of the c

We investigate the mixing layer thickness, δ(ξ), along the streamwise coordinate ξ of a straight channel fed with alternating streams of segregated solutes. We show the occurence of convection-enhanced mixing regimes downsteram the channel: i) an early-mixing regime, δ(ξ) ∼ξ 1/3 resembling the classical Lèvêque scaling of the thermal boundary layer, ii) an intermediate anomalous regime δ(ξ)∼ξ 3/5,

This article develops the theory of laminar dispersion in finite-length channel flows at high Péclet numbers, completing the classical Taylor-Aris theory which applies for long-term, long-distance properties. It is shown, by means of scaling analysis and invariant reformulation of the moment equations, that solute dispersion in finite length channels is characterized by the occurrence of a new reg

This article develops the theoretical analysis of transport and dispersion phenomena in wide-bore chromatography at values of the Peclet number Pe beyond the upper bound of validity of the Taylor-Aris theory. It is shown that for Poiseuille flows in cylindrical capillaries the average residence time grows logarithmically with the Peclet number, while the variance of the outlet chromatogram scales

This article analyses stationary scalar mixing downstream an open flow Couette device operating in the creeping flow regime. The device consists of two coaxial cylinders of finite length Lz, and radii κR and R (

We develop a quantitative analysis of mixing regimes in an annular MHD-driven micromixer recently proposed by Gleeson et al. as a prototype for biomolecular applications. The analysis is based on the spectral properties of the advection - diffusion operator, with specific focus on the dependence of the dominant eigenvalue - eigenfunction on the Peclet number and on the system geometry. A theoretic

We study the spectral properties of the advection-diffusion operator associated with a non-chaotic 3d Stokes flow defined in the annular region between counter-rotating cylinders of finite length. The focus is on the dependence of the eigenvalue-eigenfunction spectrum on the Peclet number Pe. Several convection-enhanced mixing regimes are identified, each characterized by a power law scaling, -μd∼

We investigate the steady-state performance of a planar micromixer composed of several S-shaped units. Mixing efficiency is quantified by the decay of the scalar variance downstream the device for generic feeding conditions. We discuss how this decay is controlled by the spectral properties of the advection-diffusion Floquet operator, F, that maps a generic scalar profile at the inlet of a single

Spectral properties of the weighted Laplace operator in the presence of fractal boundaries are numerically investigated for both Neumann and Dirichlet boundary conditions. This corresponds to the characterization of heat and mass transport in microchannels with irregular and rough surfaces induced by the microfabrication process. The axial velocity field with no-slip boundary conditions, represent

We develop a novel and simple theoretical model of time-interleaved sequential lamination micromixers that improves the model proposed by Nguyen and coworkers (Microfluid Nanofluid 1:373-375, 2005a, Lab Chip 5:1320-1326, b, J Phys Conf Ser 34:136-141, 2006) based on the Taylor-Aris dispersion theory. The Nguyen model takes into account the non uniform structure of the velocity profile through an e

We investigate the steady-state performance of a single irreversible mixing-controlled reaction between segregated reactant streams entering the annular gap between coaxial cylinders that can rotate independently. The three-dimensional Stokes flow results from the superposition of a pressure-driven Poiseuille flow along the mixer axis, and a cross-sectional Couette flow generated by the steady rot

We present a variational formulation of the governing equations and introduce global indicators to describe the behavior of acoustofluidic devices driven at resonance frequencies by means of a piezoelectric transducer. The individuation of the correct Lagrangian densities for the different parts constituting the device (the piezo transducer, the silicon walls, the fluid-filled microchannel, and th

This article addresses the short-term decay of advecting-diffusing scalar fields in Stokes flows. The analysis is developed in two main subparts. In the first part, we present an analytic approach for a class of simple flow systems expressed mathematically by the one-dimensional advection-diffusion equation w(y)∂ξ=É∂y2+iV(y)-É′, where ξ is either time or axial coordinate and iV(y) an imaginary pot