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Propulsion of Bubble-Based Acoustic Microswimmers
(American Physical SocietyPhysical Review Applied, 2015-12-29)
Acoustic microswimmers present a great potential for microfluidic applications and targeted drug delivery. Here, we introduce armored microbubbles (size range, 10–20 μm) made by three-dimensional microfabrication, which ...
Small-amplitude swimmers can self-propel faster in viscoelastic fluids
(ElsevierJournal of Theoretical Biology, 2015-07-08)
Many small organisms self-propel in viscous fluids using travelling wave-like deformations of their bodies or appendages. Examples include small nematodes moving through soil using whole-body undulations or spermatozoa ...
The stress–pressure relationship in simulations of MRI-induced turbulence
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2016-01-01)
We determine how MRI (magnetorotational instability)-turbulent stresses depend on gas pressure via a suite of unstratified shearing box simulations. Earlier numerical work reported only a very weak dependence at best, ...
Growth of eccentric modes in disc–planet interactions
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2016-03-07)
We formulate a set of linear equations that describe the behaviour of small eccentricities in a protoplanetary system consisting of a gaseous disc and a planet. Eccentricity propagates through the disc by means of pressure ...
Destruction of large-scale magnetic field in nonlinear simulations of the shear dynamo
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2016-03-03)
The Sun's magnetic field exhibits coherence in space and time on much larger scales than the turbulent convection that ultimately powers the dynamo. In the past the α-effect (mean-field) concept has been used to model the ...
On the convective overstability in protoplanetary discs
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2016-01-21)
This paper explores the driving of low-level hydrodynamical activity in protoplanetary-disc dead zones. A small adverse radial entropy gradient, ordinarily stabilized by rotation, excites oscillatory convection (‘convective ...
Asymptotic analysis of cold sandwich rolling
(ElsevierInternational Journal of Mechanical Sciences, 2015-12-22)
An analytical model for the cold rolling of sandwich sheets is proposed, assuming a rigid-plastic flow rule and Coulomb friction. Asymptotic analysis is used to solve the equations based on the assumptions of small aspect ...
R-Parity Violation in a Warped GUT Scale Randall-Sundrum Framework
(American Physical SocietyPhysical Review D, 2016)
We consider a modified Randall-Sundrum (RS) framework between the Planck scale and the GUT scale. In this scenario, RS works as a theory of flavour and not as a solution to the hierarchy problem. The latter is resolved by ...
Energy requirement for a working dynamo
(Taylor & FrancisGeophysical & Astrophysical Fluid Dynamics, 2015-10-13)
There has for many years been interest in finding necessary conditions for dynamo action. These are usually expressed in terms of bounds on integrated properties of the flow. The bounds can clearly be improved when the ...
Enhanced active swimming in viscoelastic fluids
(IOP PublishingEurophysics Letters, 2014-11-05)
Swimming microorganisms often self-propel in fluids with complex rheology. While past theoretical work indicates that fluid viscoelasticity should hinder their locomotion, recent experiments on waving swimmers suggest a ...