Growth and instability of the liquid rim in the crown splash regime

AbstractWe study the formation, growth and disintegration of jets following the impact of a drop on a thin film of the same liquid for $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\mathit{We}<1000$ and $\mathit{Re}<2000$ using a combination of numerical simulations and linear stability theory (Agbaglah, Josserand & Zaleski, Phys. Fluids, vol. 25, 2013, 022103). Our simulations faithfully capture this phenomena and are in good agreement with experimental profiles obtained from high-speed X-ray imaging. We obtain scaling relations from our simulations and use these as inputs to our stability analysis. The resulting predictions for the most unstable wavelength are in excellent agreement with experimental data. Our calculations show that the dominant destabilizing mechanism is a competition between capillarity and inertia but that deceleration of the rim provides an additional boost to growth. We also predict over the entire parameter range of our study the number and timescale for formation of secondary droplets formed during a splash, based on the assumption that the most unstable mode sets the droplet number.

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Splashing from drop impact into a deep pool: multiplicity of jets and the failure of conventional scaling

Journal of Fluid Mechanics ◽

10.1017/jfm.2012.249 ◽

2012 ◽

Vol 703 ◽

pp. 402-413 ◽

Cited By ~ 22

Author(s):

L. V. Zhang ◽

J. Toole ◽

K. Fezzaa ◽

R. D. Deegan

Keyword(s):

Dynamic Viscosity ◽

High Speed ◽

Drop Impact ◽

X Ray ◽

Intermediate Size ◽

Secondary Droplets ◽

The Impact ◽

Gas Properties

AbstractWe report high-speed optical and X-ray observations of jets formed during the impact of a drop with a deep pool of the same liquid. We show that a scaling that relies entirely on liquid properties, as is conventionally employed, is insufficient to determine the threshold for splashing. In order to determine if the gas properties could account for this deficit, we conducted experiments with different surrounding gases. We find that the splashing threshold depends on the gas’s dynamic viscosity, but not its density. We argue that these results are consistent with a thickening of the ejecta caused by the bubble trapped on impact between the drop and the pool. We also show that drop impact can generate a third jet, distinct from the lamella and the ejecta, that produces secondary droplets of an intermediate size.

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Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

Tire Science and Technology ◽

10.2346/1.2965832 ◽

2008 ◽

Vol 36 (3) ◽

pp. 211-226 ◽

Cited By ~ 9

Author(s):

F. Liu ◽

M. P. F. Sutcliffe ◽

W. R. Graham

Keyword(s):

High Speed ◽

Slip Rate ◽

Material Model ◽

Contact Forces ◽

Block Modeling ◽

Rate Dependent ◽

Linear Viscoelastic Material ◽

Linear Viscoelastic ◽

The Impact ◽

Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

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Dynamic model for high-speed rotors based on their experimental characterization

Application and Theory of Computer Technology ◽

10.22496/atct.v2i4.108 ◽

2017 ◽

Vol 2 (4) ◽

pp. 25

Author(s):

L. A. Montoya ◽

E. E. Rodríguez ◽

H. J. Zúñiga ◽

I. Mejía

Keyword(s):

Dynamic Model ◽

High Speed ◽

Natural Frequencies ◽

Mode Shapes ◽

Experimental Characterization ◽

Rotating Systems ◽

Computing Performance ◽

The Impact ◽

Stiffness Distribution ◽

Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

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Revealing transient powder-gas interaction in laser powder bed fusion process through multi-physics modeling and high-speed synchrotron x-ray imaging

Additive Manufacturing ◽

10.1016/j.addma.2020.101362 ◽

2020 ◽

Vol 35 ◽

pp. 101362 ◽

Cited By ~ 1

Author(s):

Xuxiao Li ◽

Cang Zhao ◽

Tao Sun ◽

Wenda Tan

Keyword(s):

High Speed ◽

Fusion Process ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

X Ray ◽

X Ray Imaging ◽

Physics Modeling

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Anin situatomic force microscope for normal-incidence nanofocus X-ray experiments

Journal of Synchrotron Radiation ◽

10.1107/s1600577516011437 ◽

2016 ◽

Vol 23 (5) ◽

pp. 1110-1117 ◽

Cited By ~ 3

Author(s):

M. V. Vitorino ◽

Y. Fuchs ◽

T. Dane ◽

M. S. Rodrigues ◽

M. Rosenthal ◽

...

Keyword(s):

Thin Film ◽

Atomic Force Microscope ◽

High Speed ◽

Normal Incidence ◽

Organic Thin Film ◽

X Ray ◽

Atomic Force ◽

Synchrotron Beamlines

A compact high-speed X-ray atomic force microscope has been developed forin situuse in normal-incidence X-ray experiments on synchrotron beamlines, allowing for simultaneous characterization of samples in direct space with nanometric lateral resolution while employing nanofocused X-ray beams. In the present work the instrument is used to observe radiation damage effects produced by an intense X-ray nanobeam on a semiconducting organic thin film. The formation of micrometric holes induced by the beam occurring on a timescale of seconds is characterized.

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UFO — a scalable platform for high-speed synchrotron X-ray imaging

2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD) ◽

10.1109/nssmic.2016.8069895 ◽

2016 ◽

Author(s):

Andreas Kopmann ◽

Suren Chilingaryan ◽

Matthias Vogelgesang ◽

Timo Dritschler ◽

Andrey Shkarin ◽

...

Keyword(s):

High Speed ◽

X Ray ◽

X Ray Imaging

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syris: a flexible and efficient framework for X-ray imaging experiments simulation

Journal of Synchrotron Radiation ◽

10.1107/s1600577517012255 ◽

2017 ◽

Vol 24 (6) ◽

pp. 1283-1295 ◽

Cited By ~ 4

Author(s):

Tomáš Faragó ◽

Petr Mikulík ◽

Alexey Ershov ◽

Matthias Vogelgesang ◽

Daniel Hänschke ◽

...

Keyword(s):

Motion Estimation ◽

Data Processing ◽

Graphics Processing Units ◽

High Speed ◽

Real Data ◽

Estimation Accuracy ◽

Processing Parameter ◽

X Ray ◽

X Ray Imaging ◽

Imaging Conditions

An open-source framework for conducting a broad range of virtual X-ray imaging experiments,syris, is presented. The simulated wavefield created by a source propagates through an arbitrary number of objects until it reaches a detector. The objects in the light path and the source are time-dependent, which enables simulations of dynamic experiments,e.g.four-dimensional time-resolved tomography and laminography. The high-level interface ofsyrisis written in Python and its modularity makes the framework very flexible. The computationally demanding parts behind this interface are implemented in OpenCL, which enables fast calculations on modern graphics processing units. The combination of flexibility and speed opens new possibilities for studying novel imaging methods and systematic search of optimal combinations of measurement conditions and data processing parameters. This can help to increase the success rates and efficiency of valuable synchrotron beam time. To demonstrate the capabilities of the framework, various experiments have been simulated and compared with real data. To show the use case of measurement and data processing parameter optimization based on simulation, a virtual counterpart of a high-speed radiography experiment was created and the simulated data were used to select a suitable motion estimation algorithm; one of its parameters was optimized in order to achieve the best motion estimation accuracy when applied on the real data.syriswas also used to simulate tomographic data sets under various imaging conditions which impact the tomographic reconstruction accuracy, and it is shown how the accuracy may guide the selection of imaging conditions for particular use cases.

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