Fluidisation of yield stress fluids under vibration

“…The present study relates to a number of previous research lines in the literature. One is the gravity-driven spreading and large-scale 3-D printing of yield stress materials, in particular concrete (Roussel & Coussot 2005;Flatt, Larosa & Roussel 2006; Ancey 958 A34-2 2007; Liu et al 2016;Gosselin et al 2016;Buswell et al 2018;Garg et al 2021;Valette et al 2021). The major differences between the present study and these works are the characteristic length scales and the driving mechanisms.…”

Section: Introductionmentioning

confidence: 78%

Viscoplastic lines: printing a single filament of yield stress material on a surface

2023

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This study presents the spreading of a single filament of a yield stress (viscoplastic) fluid extruded onto a pre-wetted solid surface. The filaments spread laterally under surface tension forces until they reach a final equilibrium shape when the yield stress dominates. We use a simple experimental set-up to print the filaments on a moving surface and measure their final width using optical coherence tomography. Additionally, we present a scaling law for the final width and determine the corresponding prefactor using asymptotic analysis. We then analyse the level of agreement between the theory and experiments, and discuss the possible origins of discrepancies. The process studied here has applications in extrusion-based thermoplastic and bio-three-dimensional printing.

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“…The high quality microgravity obtained in the ZARM drop tower allows to conduct experiments that are very sensitive to gravity-jitters. This high quality is important in droplet-spreading experiments, since in principle, yield-stress fluid droplets could be sensitive to vibration-induced deformations that complicate the measurements 37 .…”

Section: Specifications a Microgravity Platformmentioning

confidence: 99%

VIP-DROP2: A module for characterization of the spread of complex fluids droplets under various gravitational accelerations

Olfa¹,

Kuthe²,

Nieuwland³

et al. 2022

Preprint

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Axisymmetric droplets provide a demonstration system to study the spread of complex fluids, which are an essential component of industrial and technological processes, among which additive manufacturing (AM). Tweaking the gravitational environment provides access to different regimes, quantified through the Bond number; in particular, microgravity allows to form large droplets while remaining in the regime where the surface tension effects and internal driving stresses are predominant over hydrostatic forces. The vip-drop 2 module offers a versatile platform to study a wide range of complex fluids through the deposition of initially axisymmetric droplets. It offers the possibility to deposit the droplets on a precursor layer: a thin, homogeneous layer, which can be made of the same or of a different fluid. Besides, it allows to deposit simultaneously 4 droplets, while conducting shadowgraphy on all of them, and observing either the flow field through particle image velocimetry (PIV), or the stress distribution within the droplet in the case of stress birefringent materials. Developed for a drop tower catapult system, it is designed to withstand a vertical acceleration of up to 30 times the gravity of Earth in the downwards direction, and can operate remotely, under microgravity conditions.

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Fluidisation of yield stress fluids under vibration

Cited by 23 publications

References 34 publications