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...

Long-time-scale transients in an industrial-scale slurry pipeline near the laminar–turbulent transition

We revisit the laminar–turbulent transition of a fine-grained slurry in a large pipe. The combination of long measurement times in an industrial-scale facility and ultrasound imaging allows us to observe and address anomalous trends. Under turbulent conditions, the flow is homogeneous and steady. However, under laminar conditions, two types of...

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...

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....

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...

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...

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...