Effect of finite container size on granular jet formation

Kann, Stefan von; Joubaud, Sylvain; Caballero‐Robledo, Gabriel A.; Lohse, Detlef; Meer, Devaraj van der

doi:10.1103/physreve.81.041306

Cited by 22 publications

(21 citation statements)

References 21 publications

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“…Worthington & Cole (1897, 1900 and Worthington (1908) were the first to investigate cavity formation and splash characteristics produced by spheres impacting onto liquid surfaces using single-spark illumination photography. Following their work, Mallock (1918), Bell (1924) and Ramsauer & Dobke (1927) provided further descriptions of the observed cavity characteristics, while the first sets of quantitative results were presented by Gilbarg & Anderson (1948), Richardson (1948), May & Woodhull (1948, 1950 and May (1951May ( , 1952 who collectively investigated sphere impacts with water surfaces, highlighting the influence of atmospheric pressure, overall impact forces involved and the effect of the sphere wettability on the observed cavity and splash characteristics.…”

Section: Introductionmentioning

confidence: 99%

Water entry without surface seal: extended cavity formation

et al. 2014

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We report results from an experimental study of cavity formation during the impact of superhydrophobic spheres onto water. Using a simple splash-guard mechanism, we block the spray emerging during initial contact from closing thus eliminating the phenomenon known as 'surface seal', which typically occurs at Froude numbers Fr = V 2 0 /(gR 0 ) = O(100). As such, we are able to observe the evolution of a smooth cavity in a more extended parameter space than has been achieved in previous studies. Furthermore, by systematically varying the tank size and sphere diameter, we examine the influence of increasing wall effects on these guarded impact cavities and note the formation of surface undulations with wavelength λ = O(10) cm and acoustic waves λ a = O(D 0 ) along the cavity interface, which produce multiple pinch-off points. Acoustic waves are initiated by pressure perturbations, which themselves are generated by the primary cavity pinch-off. Using high-speed particle image velocimetry (PIV) techniques we study the bulk fluid flow for the most constrained geometry and show the larger undulations (λ = O(10 cm)) have a fixed nature with respect to the lab frame. We show that previously deduced scalings for the normalized (primary) pinch-off location (ratio of pinch-off depth to sphere depth at pinch-off time), H p /H = 1/2, and pinch-off time, τ ∝ (R 0 /g) 1/2 , do not hold for these extended cavities in the presence of strong wall effects (sphere-to-tank diameter ratio), = D 0 /D tank 1/16. Instead, we find multiple distinct regimes for values of H p /H as the observed undulations are induced above the first pinch-off point as the impact speed increases. We also report observations of 'kinked' pinch-off points and the suppression of downward facing jets in the presence of wall effects. Surprisingly, upward facing jets emanating from first cavity pinch-off points evolve into a 'flat' structure at high impact speeds, both in the presence and absence of wall effects.

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Section: Introductionmentioning

confidence: 99%

Water entry without surface seal: extended cavity formation

et al. 2014

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“…The motion of the impactor, often a dense sphere, in the bed is used to deduce the form of the drag force exerted on the sphere, since it is normally found [8][9][10][11][12][13][14][15][16][17][18] that a sphere comes to rest at a finite depth below the initial surface level of the bed (note the exceptional results of Ref. [7], showing that the sphere reaches a terminal velocity, resulting in infinite penetration).…”

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confidence: 99%

Sphere impact and penetration into wet sand

2012

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We present experimental results for the penetration of a solid sphere when released onto wet sand. We show, by measuring the final penetration depth, that the cohesion induced by the water can result in either a deeper or shallower penetration for a given release height compared to dry granular material. Thus the presence of water can either lubricate or stiffen the granular material. By assuming the shear rate is proportional to the impact velocity and using the depth-averaged stopping force in calculating the shear stress, we derive effective viscosities for the wet granular materials.

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“…A last case corresponds to the impact problem, when an object penetrates vertically the granular layer [18][19][20][21][22][23][24]. In all these situations, a rich phenomenology has been observed and the velocity dependence [9,16], the effect of the boundaries [20,25], and the existence of lift forces associated with the motion [17] have been studied. One major feature common to all the above configurations is the frictional scaling of the drag force in the limit of quasistatic motions.…”

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confidence: 99%