Dynamic jamming of dense suspensions under tilted impact

Abstract

Dense particulate suspensions can not only increase their viscosity and shear thicken under external forcing, but also jam into a solid-like state that is fully reversible when the force is removed. An impact on the surface of a dense suspension can trigger this jamming process by generating a shear front that propagates into the bulk of the system. Tracking and visualizing such a front is difficult because suspensions are optically opaque and the front can propagate as fast as several meters per second. Recently, high-speed ultrasound imaging has been used to overcome this problem and extract two-dimensional sections of the flow field associated with jamming front propagation. Here we extend this method to reconstruct the three-dimensional flow field. This enables us to investigate the evolution of jamming fronts for which axisymmetry cannot be assumed, such as impact at angles tilted away from the normal to the free surface of the suspension. We find that sufficiently far from solid boundaries the resulting flow field is approximately identical to that generated by normal impact, but rotated and aligned with the angle of impact. However, once the front approaches the solid boundary at the bottom of the container, it generates a squeeze flow that deforms the front profile and causes jamming to proceed in a non-axisymmetric manner. * These two authors contributed equally †

Getting jammed in all directions: Dynamic shear jamming around a cylinder towed through a dense suspension

“…For the quasi 1D, transient, simple shear system described in [7,8], a model linking the front propagation k with the packing fraction φ was developed. In the experiment described here, we observe many of the phenomena expected from experiment of similar nature [2][3][4][5][6]. That is, a constant front propagation with a relation 1 : 2 between the transverse and longitudinal direction.…”

“…As noted in the discussion above, it has been shown how strain influences the flow for simpler systems [8], where strain reduces down to a scalar. Other experiments investigating shear jamming fronts in more complex systems focus only on the behaviour in front of [2,4,5] or behind [1] the perturbing body separately, thus the jamming front produced in these studies propagates in the fore or aft half-planes only. How the 2D flow develops around a translating body, producing jamming fronts in the full circumference simultaneously, has not been observed until now.…”

“…The transient development of a dynamically jammed region has been investigated extensively in experiments where the applied stress has been in the form of pulling [1], pushing [2][3][4][5] or shearing [6][7][8]. In these works, the different cases have been addressed separately, but how these three scenarios interact in a single system has remained unexplored.…”

Viscous-like forces control the impact response of shear-thickening dense suspensions

“…cornstarch mixed with water or another liquid at ) by a foreign intruder can be similarly dramatic (Lee, Wetzel & Wagner 2003; Waitukaitis & Jaeger 2012; Peters & Jaeger 2014; Han, Peters & Jaeger 2016; Mukhopadhyay, Allen & Brown 2018; Han et al. 2019 b ; Pradipto & Hayakawa 2021). Yet, a simple application of steady-state rheology cannot explain the impact response, as the stresses predicted by DST are far too small to, e.g.…”

Characterizing the surface texture of a dense suspension undergoing dynamic jamming

“…In sufficiently large domains, the transition from fluid-like to solid-like is observed as a front of high shear rate that propagates from the perturbing body through the suspension and leaves a jammed state in its wake (Waitukaitis and Jaeger 2012;Peters and Jaeger 2014;Han et al 2016;Peters et al 2016;Majumdar et al 2017;Han et al 2018Han et al , 2019bBaumgarten and Kamrin 2019;Rømcke et al 2021). In these works, the jamming front is defined by the velocity contour at half the velocity of the perturbing body, i.e., 0.5U c .…”