scholarly journals A drop does not fall in a straight line: a rationale for the width of stalagmites

2019 ◽  
Vol 475 (2231) ◽  
pp. 20190556 ◽  
Author(s):  
J. Parmentier ◽  
S. Lejeune ◽  
M. Maréchal ◽  
F. Bourges ◽  
D. Genty ◽  
...  
Keyword(s):  
Calcium Ions ◽  
High Speed ◽  
Free Fall ◽  
Impact Point ◽  
Calcite Precipitation ◽  
High Speed Imaging ◽  
Point Position ◽  
Straight Line ◽  
The Impact

Drops loaded in calcium ions detach from stalactites and impact the underlying stalagmites, thereby allowing these latter to grow through calcite precipitation. Nevertheless, little is known about the influence of the drop free fall and splash dynamics on stalagmite shape and width. Through high-speed imaging of impacting drops on stalagmites from several caves, we observed that the impact point position of the drops is scattered, sometimes over several centimetres. We show that this dispersal has no external cause and must, therefore, be self-induced. Using a Langevin-like equation, we then propose a prediction of the impact point dispersal as a function of the falling height travelled by the drops. We finally show that measured stalagmite widths are correlated to the dispersal in the impact point position of the drop.

scholarly journals Air mediates the impact of a compliant hemisphere on a rigid smooth surface

Soft Matter ◽  
2021 ◽  
Author(s):  
Siqi Zheng ◽  
Sam Dillavou ◽  
John M. Kolinski
Keyword(s):  
Elastic Body ◽  
Elastic Properties ◽  
Impact Velocity ◽  
Solid Surface ◽  
High Speed ◽  
Smooth Surface ◽  
High Speed Imaging ◽  
The Impact ◽  
Rigid Smooth

When a soft elastic body impacts upon a smooth solid surface, the intervening air fails to drain, deforming the impactor. High-speed imaging with the VFT reveal rich dynamics and sensitivity to the impactor's elastic properties and the impact velocity.

scholarly journals When does a granular material behave like a continuum fluid?

2012 ◽  
Vol 704 ◽  
pp. 1-4 ◽  
Author(s):  
John R. de Bruyn
Keyword(s):  
Granular Material ◽  
Temporal Resolution ◽  
High Speed ◽  
High Impact ◽  
High Temporal Resolution ◽  
Granular Bed ◽  
Fluid Limit ◽  
High Speed Imaging ◽  
Impact Energies ◽  
The Impact

AbstractA flowing granular material can behave like a collection of individual interacting grains or like a continuum fluid, depending in large part on the energy imparted to the grains. As yet, however, we have no general understanding of how or under what conditions the fluid limit is reached. Marston, Li & Thoroddsen (J. Fluid Mech., this issue, vol. 704, 2012, pp. 5–36) use high-speed imaging to investigate the ejection of grains from a granular bed due to the impact of a spherical projectile. Their high temporal resolution allows them to study the very fast processes that take place immediately following the impact. They demonstrate that for very fine grains and high impact energies, the dynamics of the ejecta is both qualitatively and quantitatively similar to what is seen in analogous experiments with fluid targets.

scholarly journals Experimental and Analytical Characterization of Drop Impact Behavior for a Mobile Haptic Actuator

2017 ◽  
Author(s):  
Byungjoo Choi ◽  
Jiwoon Kwon ◽  
Yongho Jeon ◽  
Moon Gu Lee
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Free Fall ◽  
Element Model ◽  
Impact Behavior ◽  
Air Resistance ◽  
Impact Reliability ◽  
The Impact ◽  
The Finite Element Model

Impact characterization of linear resonant actuator (LRA) is studied experimentally by newly developed drop tester, which can control various experimental uncertainty such as rotational moment, air resistance, secondary impact and so on. The feasibility of this test apparatus was verified by comparison with free fall test. By utilizing a high-speed camera and measuring the vibrational displacement of spring material, the impact behavior was captured and the damping ratio of the system was defined. Based on the above processes, the finite element model was established and the experimental and analytical results were successfully correlated. Finally, the damage of the system from impact loading can be expected by developed model and as a result, this research can improve the impact reliability of LRA.

The Impact of Vertical Deflection on the Ballistic Missiles for Direction and Positioning

2014 ◽  
Vol 568-570 ◽  
pp. 938-943 ◽  
Author(s):  
Jian Qiang Wang ◽  
Hua Ling Wu
Keyword(s):  
Long Range ◽  
Target Point ◽  
Impact Point ◽  
Vertical Deflection ◽  
Point Position ◽  
Simulation Based ◽  
Ballistic Missiles ◽  
The Impact

The direction and positioning of the missile could be affected by the vertical deflection which is at the launch point, so the impact point errors will increase. Based on the launch coordination, the target point position deviation formula which is caused by vertical deflection is deduced in this paper. The correction precise of the vertical deflection is also a factor of the impact point error. The simulation based on the deviation formula is conducted to analyze the affection of the vertical deflection and the correction precise of the vertical deflection. And the results show that the vertical deflection can lead to 1km error for the long range missile. In addition, if the precision of vertical deflection were improved , the impact point errors will be reduced 85m.

scholarly journals Bubble Dynamics in a Narrow Gap Flow under the Influence of Pressure Gradient and Shear Flow

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 208
Author(s):  
Peter Reinke ◽  
Jan Ahlrichs ◽  
Tom Beckmann ◽  
Marcus Schmidt
Keyword(s):  
Shear Flow ◽  
Pressure Gradient ◽  
High Speed ◽  
Bubble Dynamics ◽  
Three Dimensional ◽  
High Speed Imaging ◽  
Two Phase ◽  
Bubble Generation ◽  
Gap Flow ◽  
The Impact

The volume-of-flow method combined with the Rayleigh–Plesset equation is well established for the computation of cavitation, i.e., the generation and transportation of vapor bubbles inside a liquid flow resulting in cloud, sheet or streamline cavitation. There are, however, limitations, if this method is applied to a restricted flow between two adjacent walls and the bubbles’ size is of the same magnitude as that of the clearance between the walls. This work presents experimental and numerical results of the bubble generation and its transportation in a Couette-type flow under the influence of shear and a strong pressure gradient which are typical for journal bearings or hydraulic seals. Under the impact of variations of the film thickness, the VoF method produces reliable results if bubble diameters are less than half the clearance between the walls. For larger bubbles, the wall contact becomes significant and the bubbles adopt an elliptical shape forced by the shear flow and under the influence of a strong pressure gradient. Moreover, transient changes in the pressure result in transient cavitation, which is captured by high-speed imaging providing material to evaluate transient, three-dimensional computations of a two-phase flow.

The impact of viscoplastic drops on a heated surface in the Leidenfrost regime

Soft Matter ◽  
2016 ◽  
Vol 12 (36) ◽  
pp. 7624-7631 ◽  
Author(s):  
Simeng Chen ◽  
Volfango Bertola
Keyword(s):  
High Speed ◽  
Heated Surface ◽  
High Speed Imaging ◽  
The Impact

The impact morphology of viscoplastic drops on a heated surface in the Leidenfrost regime is investigated experimentally by high-speed imaging.

scholarly journals COMPARATIVE ANALYSIS OF GOLF CLUBHEAD MOTION AT IMPACT

2020 ◽  
pp. 437
Author(s):  
Simon Kraśna ◽  
Milan Čoh ◽  
Ivan Prebil ◽  
Krzysztof Mackala
Keyword(s):  
High Speed ◽  
Imaging System ◽  
Narrow Range ◽  
Golf Swing ◽  
Body Type ◽  
Additional Insight ◽  
High Speed Imaging ◽  
Circular Arc ◽  
Impact Phase ◽  
The Impact

The purpose of the study was to investigate clubhead kinematics during the impact phase of a golf swing. Three highly skilled golfers of a distinguished body type were instructed to perform driver, 6-iron and pitching wedge trials. A high-speed imaging system was used to capture the clubhead motion near the impact. Conventional golf swing parameters were analysed for comparison. Additionally, a circular arc was fitted to the clubhead path, and the moving trihedron was introduced as a reference frame for observing the clubhead rotation. Despite differences in their body type, golfers achieved comparable clubhead speed, while the radius of the fitted circular arc was in a narrow range. The moving trihedron, together with conventional parameters of the golf swing, enabled additional insight to the clubhead motion and clubface orientation. Individual swing characteristics, which result in the clubhead motion prior to impact, could clearly be observed, enabling improvement of the golfer’s swing technique.

Time-dependent measurements of length and area of the contact line in contact-boiling regime

2021 ◽  
Vol 926 ◽  
Author(s):  
Mohammad Khavari ◽  
Tuan Tran
Keyword(s):  
Contact Line ◽  
Contact Area ◽  
High Speed ◽  
Liquid Droplet ◽  
Heated Surface ◽  
Bubble Nucleation ◽  
High Speed Imaging ◽  
Wide Range ◽  
Length And Area ◽  
The Impact

During the impact of a liquid droplet on a sufficiently heated surface, bubble nucleation reduces the contact area between the liquid and the solid surface. Using high-speed imaging combined with total internal reflection, we measure and report how the contact area decreases with time for a wide range of surface temperatures and impact velocities. We also reveal how formation of the observed fingering patterns contributes to a substantial increase in the total length of the contact line surrounding the contact area.

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