Particle-laden Taylor-Couette flows: Higher-order transitions and evidence for azimuthally localized wavy vortices

We extend upon the known flow transitions in neutrally buoyant particle-laden Taylor-Couette flows by accessing higher suspension Reynolds numbers in a geometry with radius ratio and aspect ratio. Flow transitions for several particle volume fractions () are investigated by means of flow visualization experiments, in a flow driven by a...

Effect of hydrodynamic slip on the rotational dynamics of a thin Brownian platelet in shear flow

The classical theory by Jeffery predicts that, in the absence of Brownian fluctuations, a thin rigid platelet rotates continuously in a shear flow, performing periodic orbits. However, a stable orientation is possible if the surface of the platelet displays a hydrodynamic slip length comparable to or larger than the thickness of the platelet....

Polydispersity effect on dry and immersed granular collapses: an experimental study

The column collapse experiment is a simplified version of natural and industrial granular flows. In this set-up, a column built with grains collapses and spreads over a horizontal plane. Granular flows are often studied with a monodisperse distribution; however, this is not the case in natural granular flows where a variety of grain sizes, known...

On the orientational dependence of drag experienced by spheroids

The flow around different prolate (needle-like) and oblate (disc-like) spheroids is studied using a multi-relaxation-time lattice Boltzmann method. We compute the mean drag coefficient CD,ϕ at different incident angles ϕ for a wide range of Reynolds numbers ( Re ). We show that the sine-squared drag law CD,ϕ=CD,ϕ=0∘+(CD,ϕ=90∘−CD,ϕ=0∘)sin2ϕ holds...

Combined three-dimensional flow field measurements and motion tracking of freely moving spheres in a turbulent boundary layer

A combination of time-resolved tomographic particle image velocimetry, refractive index matching technique and machine vision algorithms was used to measure the translational and rotational motion of freely moving, nearly neutrally buoyant spheres in a fully developed turbulent boundary layer (TBL). Located in the buffer and logarithmic...

Formation and break-up of rigid agglomerates in turbulent channel and pipe flows

We have developed and applied an Eulerian-Lagrangian model for the transport, formation, break-up, deposition and re-entrainment of particle agglomerates. In this paper, we focus on agglomeration and break-up. Simulations were carried out to investigate what changes in the turbulent flow are inflicted by the presence of the agglomerates. Also...

Role of turbulent kinetic energy modulation by particle–fluid interaction in sediment pick-up

Reliable prediction of the erosion rate of sediment beds is important for many applications in coastal and river engineering. Theoretical understanding of empirically derived scaling relations is still lacking. This applies in particular for the scaling anomaly between low and high Shields number conditions. In this work, the erosion process is...