Degenerate states, emergent dynamics and fluid mixing by magnetic rotors

Abstract

We investigate the collective motion of magnetic rotors suspended in a viscous fluid under a uniform rotating magnetic field. We report there are three collective rotational patterns: synchronized, oscillating and chessboard patterns.

An experimental study of the merging flow of polymer solutions in a T-shaped microchannel

“…Note that the Weissenberg number for water is set to Wi = 0.0001 for all flow rates in order to include its data into the log-log plot. This same value is also assigned to the inelastic XG solution for the smallest flow rate of 0.2 ml h À1 , based on which Wi at higher flow rates can be calculated using eqn (3). Two isolines are utilized in Fig.…”

“…Microfluidic systems often require the integration of a series of planar geometries to perform multiple functionalities on a single platform. 1,2 A frequently encountered geometry therein is a T-shaped junction because of its relevance to sample mixing, 3,4 particle focusing, 5 particle trapping, 6 and particle separation, 7 etc., where the two fluids coming from the oppositely facing side branches merge and flow through the main branch with the stagnation point pinned at the wall (named as merging flow hereafter). On one hand, a good mixing of samples relies on the flow instabilities induced at the interface of the incoming fluids because otherwise the samples therein can only be slowly exchanged through molecular diffusion.…”

Self-Sustained Rotation of Lorentz Force-Driven Janus Systems

“…Self-propelled dynamic devices have gained considerable attention due to the increasing number of applications ranging from sensing to environmental remediation. − In this context, rotation of macro-, micro-, and nanodevices is a particular type of motion that is involved in many technological applications, i.e ., energy transformation, pumping, or propulsion. − Although such kind of motion can be typically triggered by connecting an object to an external motor, recently, far more sophisticated external stimuli have been proposed. Rotation of macro-, micro-, and nanodevices, powered by the Marangoni effect, − light, , sound, , or electric and magnetic fields, has been achieved. − In particular, the latter has gained considerable attention due to the possible control of the rotation trajectory (clockwise or anticlockwise), simply by changing the orientation of the magnetic field ( B ). However, this type of device requires using sophisticated experimental setups with ferromagnetic components and non-stationary magnetic flux, which limits the potential applicability.…”

“…Rotation of macro-, micro-, and nanodevices, powered by the Marangoni effect, 15 − 20 light, 21 , 22 sound, 23 , 24 or electric and magnetic fields, has been achieved. 25 − 33 In particular, the latter has gained considerable attention due to the possible control of the rotation trajectory (clockwise or anticlockwise), simply by changing the orientation of the magnetic field ( B ). However, this type of device requires using sophisticated experimental setups with ferromagnetic components and non-stationary magnetic flux, which limits the potential applicability.…”

Wireless Magnetoelectrochemical Induction of Rotational Motion

“…energy conversion, propulsion, or pumping. Different approaches for the generation of motion, involving gradients of surface tension (Marangoni effect), [ 1 , 2 , 3 , 4 ] chemical composition [ 5 ] and temperature, [ 6 ] or external stimuli such as light, [ 7 , 8 ] sound [ 9 , 10 ] or electric [ 11 , 12 ] and magnetic fields, [ 13 , 14 , 15 , 16 , 17 , 18 ] have been explored and are practically used. In this context, the electromagnetic induction of rotation is the basis of many devices used in daily life, such as electric motors, generators, or alternators.…”