Molecular-Scale Reagent Transport-Induced Modification of Low Weber Number Droplet Impact Dynamics

2007 ◽  
Author(s):  
Kalpak P. Gatne ◽  
Raj M. Manglik ◽  
Milind A. Jog
Keyword(s):  
High Speed ◽  
Surfactant Concentration ◽  
Water Drop ◽  
Pure Water ◽  
Sodium Dodecyl ◽  
Hydrophobic Surface ◽  
Video Camera ◽  
Impact Dynamics ◽  
Dynamic Surface ◽  
The Impact

Effect of surfactant molecular mass transport on the normal impact and spreading of a droplet of its aqueous solution on dry horizontal substrates is investigated for a range of Weber numbers (We = 20 – 100). The impact dynamics, spreading and recoil behavior are captured using a high-speed digital video camera at 4000 frames per second. Digital image-processing software was used to determine the drop spread and height of the liquid film on the surface from each frame. Experiments were performed with water and with two different aqueous solutions of Sodium Dodecyl Sulphate (SDS), one at its half critical micelle concentration (CMC) and another at twice CMC, on a hydrophilic surface (glass) and a hydrophobic surface (Teflon). It is seen that surfactant concentration, its dynamic surface tension behavior, and surface wettability govern the transient impact-spreading-recoil phenomena. A droplet of SDS solution exhibits higher maximum spread and weaker surface oscillations compared to a pure water drop colliding with the same velocity. On a hydrophobic (Teflon) surface, the drop rebound is inhibited by the presence of the surfactant. These effects are more pronounced at surfactant concentration of twice CMC compared to that at half CMC.

Experimental Investigation of Low Weber Number Post-Impact Drop Spreading on Solid Substrates

2010 ◽  
Author(s):  
Milind A. Jog ◽  
Raj M. Manglik
Keyword(s):  
Surface Tension ◽  
High Speed ◽  
Pure Water ◽  
Surfactant Solution ◽  
Video Camera ◽  
Dynamic Surface Tension ◽  
Temporal Variations ◽  
Dynamic Surface ◽  
Post Impact ◽  
Triton X

The post-impact spreading and recoil behaviors of droplets of pure liquids (water and ethanol) and aqueous solution of Triton X-100 (a surfactant) on a dry horizontal hydrophilic (glass) substrate are investigated for low Weber numbers. The evolution of drop shape during spreading and recoil are captured using a high-speed (4,000 frames per second) digital video camera. Digital image-processing was used to determine the spread and height of the liquid film on the surface from each frame. Unlike pure liquids, the liquid-gas interfacial tension for surfactant solution is a function of surface age, where surface tension is that of the solvent at zero time and then reaches an equilibrium value with increasing surface age. Furthermore, the equilibrium surface tension is a function of the surfactant concentration, which decreases from that of the solvent at zero concentration to that at the critical micelle concentration (CMC), and remains essentially constant thereafter. The surface tension of aqueous Triton X-100 solution varies from that of pure water to nearly that of ethanol. As such the comparison of transient droplet-impact-spreading-recoil behavior of the three liquids, or their temporal variations of the spread and the flattening factor, provides a basis for understanding the role of dynamic surface tension and surface wettability.

Multi-Body Impact Motion With Friction: Analysis, Simulation, and Experimental Validation

1990 ◽  
Author(s):  
Inhwan Han ◽  
B. J. Gilmore
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Impact Dynamics ◽  
Body System ◽  
High Speed Video Camera ◽  
Multi Body ◽  
The Impact ◽  
Friction Analysis ◽  
Impact Motion

Abstract When a multi-body system collides with a single body or with another multi-body system, impact dynamics with friction should be considered. This paper presents a general computer oriented analysis of impact dynamics incorporating friction. The presence of friction between sliding contacts during the impact makes the problem difficult since the events such as reverse sliding or sticking, which may occur at different times throughout the impact, must be determined. The boundary representations of the bodies are used to solve for the velocities at the points of contact. Using this information and a classification of the modes of impact, the frictional impact with sliding contact problem is solved. Using a high speed video camera, the resulting computer strategy is experimentally verified. Simulation and experimental results agree.

Multi-Body Impact Motion with Friction—Analysis, Simulation, and Experimental Validation

1993 ◽  
Vol 115 (3) ◽  
pp. 412-422 ◽  
Author(s):  
Inhwan Han ◽  
B. J. Gilmore
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Impact Dynamics ◽  
Body System ◽  
High Speed Video Camera ◽  
Multi Body ◽  
The Impact ◽  
Friction Analysis ◽  
Impact Motion

When a multi-body system collides with a single body or with another multi-body system, impact dynamics with friction should be considered. This paper presents a general computer oriented analysis of impact dynamics incorporating friction. The presence of friction between sliding contacts during the impact makes the problem difficult since the events such as reverse sliding or sticking, which may occur at different times throughout the impact, must be determined. The boundary representations of the bodies are used to solve for the velocities at the points of contact. Using this information and a classification of the modes of impact, the frictional impact with sliding contact problem is solved. Using a high speed video camera, the resulting computer strategy is experimentally verified. Simulation and experimental results agree.

Impact patterns and temporal evolutions of water drops impinging on a rotating disc

2011 ◽  
Vol 226 (4) ◽  
pp. 956-967 ◽  
Author(s):  
J-Y Li ◽  
X-F Yuan ◽  
Q Han ◽  
G Xi
Keyword(s):  
High Speed ◽  
Water Drop ◽  
Video Camera ◽  
Drop Impact ◽  
Rossby Number ◽  
Rotating Disc ◽  
Factors Affecting ◽  
Radial Spread ◽  
Spread Factor ◽  
The Impact

The impact process of a water drop colliding with a rotating disc was recorded and analysed using a high-speed video camera. Four falling velocities of the drop, eight rotational speeds, and four impacting radii of the disc were chosen to study their influences on the outcomes of drop impact. The correlation of the deposition–splash boundary was found to be the function of Reynolds number, Weber number, and Rossby number. Four kinds of impact processes were classified in terms of Rossby number and several new stages of the impact outcomes not present in drop impact on a stationary plate were recognized. For deposition processes, the temporal evolutions of two spread factors, the tangential and radial spread factors, were analysed in detail. It was found that the Rossby number and the falling velocity of the drop are the major factors affecting the tangential spread factor. In contrast, the Rossby number has little effect on the radial spread factor while the falling velocity of the drop still exerts a considerable influence on it.

Time Evolutions of Water Drops Impacting on a Rotating Disk

2011 ◽  
Vol 354-355 ◽  
pp. 609-614
Author(s):  
Jing Yin Li ◽  
Xiao Fang Yuan ◽  
Qiang Han
Keyword(s):  
High Speed ◽  
Water Drop ◽  
Experimental Studies ◽  
Rotating Disk ◽  
Deposition Process ◽  
Video Camera ◽  
Rossby Number ◽  
High Speed Video Camera ◽  
Water Drops ◽  
The Impact

Experimental studies of a water drop impinging on a rotating disk using a high-speed video camera have been performed. The photos of the impact were analyzed in detail. Three kinds of the deposition patterns were observed with the variation in Rossby number. It is found that Rossby number plays an important role in the deposition process of the drop impacting on the rotating disk, leading to some new stages not observed for drop impact on a stationary plate.

scholarly journals Detonation effects of shallow buried explosive in sandy soil on target plate acceleration in a small-scale blast test

2018 ◽  
Vol 192 ◽  
pp. 02028
Author(s):  
Hassan Zulkifli Abu ◽  
Ibrahim Aniza ◽  
Mohamad Nor Norazman
Keyword(s):  
Sandy Soil ◽  
High Speed ◽  
Early Stage ◽  
Time History ◽  
Video Camera ◽  
Small Scale ◽  
Target Plate ◽  
Air Blast ◽  
High Speed Video Camera ◽  
The Impact

Small-scale blast tests were carried out to observe and measure the influence of sandy soil towards explosive blast intensity. The tests were to simulate blast impact imparted by anti-vehicular landmine to a lightweight armoured vehicle (LAV). Time of occurrence of the three phases of detonation phase in soil with respect to upward translation time of the test apparatus were recorded using high-speed video camera. At the same time the target plate acceleration was measured using shock accelerometer. It was observed that target plate deformation took place at early stage of the detonation phase before the apparatus moved vertically upwards. Previous data of acceleration-time history and velocity-time history from air blast detonation were compared. It was observed that effects of soil funnelling on blast wave together with the impact from soil ejecta may have contributed to higher blast intensity that characterized detonation in soil, where detonation in soil demonstrated higher plate velocity compared to what occurred in air blast detonation.

Pool Boiling Heat Transfer in Aqueous Solutions of an Anionic Surfactant

2000 ◽  
Vol 122 (4) ◽  
pp. 708-715 ◽  
Author(s):  
V. M. Wasekar ◽  
R. M. Manglik
Keyword(s):  
Anionic Surfactant ◽  
Pure Water ◽  
Pool Boiling ◽  
Sodium Dodecyl ◽  
Dynamic Surface Tension ◽  
Nucleate Boiling ◽  
Optimum Level ◽  
Lauryl Sulfate ◽  
Dynamic Surface ◽  
Influence Of Temperature On

Saturated nucleate pool boiling of aqueous surfactant solutions on a horizontal cylindrical heater has been experimentally investigated. Sodium dodecyl or lauryl sulfate (SDS or SLS), an anionic surfactant, is employed. Boiling performance, relative to that for pure water, is found to be enhanced significantly by the presence of SDS, with an early onset of nucleate boiling. An optimum level of enhancement is observed in solutions at or near critical micelle concentration of the surfactant; the enhancement, however, decreases considerably in higher concentration solutions. The dynamic surface tension measurements indicate a substantial influence of temperature on the overall adsorption isotherm. The diffusion kinetics of surfactant molecules and micelles is, therefore, expected to be quite different at boiling temperature than at room temperature. This greatly modifies the boiling mechanism that is generally characterized by the formation of smaller-size bubbles with increased departure frequencies, and a decreased tendency to coalesce which causes considerable foaming. [S0022-1481(00)00704-0]

Splash formation by spherical drops

2001 ◽  
Vol 427 ◽  
pp. 73-105 ◽  
Author(s):  
LIOW JONG LENG
Keyword(s):  
High Resolution ◽  
Quantitative Data ◽  
Water Surface ◽  
High Speed ◽  
Scaling Laws ◽  
Capillary Wave ◽  
Water Drop ◽  
Qualitative And Quantitative ◽  
High Resolution Images ◽  
The Impact

The impact of a spherical water drop onto a water surface has been studied experimentally with the aid of a 35 mm drum camera giving high-resolution images that provided qualitative and quantitative data on the phenomena. Scaling laws for the time to reach maximum cavity sizes have been derived and provide a good fit to the experimental results. Transitions between the regimes for coalescence-only, the formation of a high-speed jet and bubble entrapment have been delineated. The high-speed jet was found to occur without bubble entrapment. This was caused by the rapid retraction of the trough formed by a capillary wave converging to the centre of the cavity base. The converging capillary wave has a profile similar to a Crapper wave. A plot showing the different regimes of cavity and impact drop behaviour in the Weber–Froude number-plane has been constructed for Fr and We less than 1000.

Subcooled Boiling of Surfactant Solutions

2000 ◽  
Author(s):  
G. Hetsroni ◽  
M. Gurevich ◽  
A. Mosyak ◽  
R. Rozenblit ◽  
L. P. Yarin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Speed ◽  
Heated Surface ◽  
Pure Water ◽  
Video Camera ◽  
Subcooled Boiling ◽  
Bubble Behavior ◽  
Boiling Hysteresis

Abstract During subcooled boiling of pure water and water with cationic surfactants, the motion of bubbles and the temperature of the heated surface were recorded by both a high-speed video camera and an infrared radiometer. The results show that the bubble behavior and the heat transfer mechanism for the surfactant are quite different from those of clear water. Bubbles formed in Habon G solutions were much smaller man those in water and the surface was covered with them faster. Boiling hysteresis is found for degraded solutions. Dependencies of heat transfer coefficient for various solutions were obtained and compared. The boiling curves of surfactant are quite different from the boiling curve of pure water. Experimental results demonstrate that the heat transfer coefficient of the boiling process can be enhanced considerably by the addition of a small amount of Habon G. The experiments show that the limitations of the ER technique with respect to frequency response are outweighed by its unique capacity to measure wall temperature distribution with high spatial resolution over an area encompassing many nucleation sites and over long periods.

Experimental Investigation of Droplet Dynamics on Solid Surfaces: Spreading and Recoil Effects

2006 ◽  
Author(s):  
Kalpak P. Gatne ◽  
Milind A. Jog ◽  
Raj M. Manglik
Keyword(s):  
Surface Tension ◽  
High Speed ◽  
Lower Surface ◽  
Video Camera ◽  
Temporal Variations ◽  
Liquid Viscosity ◽  
Viscous Effects ◽  
Droplet Dynamics ◽  
Digital Video Camera ◽  
The Impact

A study of the normal impact of liquid droplets on a dry horizontal substrate is presented in this paper. The impact dynamics, spreading and recoil behavior are captured using a high-speed digital video camera at 2000 frames per second. A digital image processing software was used to determine the drop spread and height of the liquid on the surface from each frame. To ascertain the effects of liquid viscosity and surface tension, experiments were conducted with four liquids (water, ethanol, propylene glycol and glycerin) that have vastly different fluid properties. Three different Weber numbers (20, 40, and 80) were considered by altering the height from which the drop is released. The high-speed photographs of impact, spreading and recoil are shown and the temporal variations of dimensionless drop spread and height are provided in the paper. The results show that changes in liquid viscosity and surface tension significantly affect the spreading and recoil behavior. For a fixed Weber number, lower surface tension promotes greater spreading and higher viscosity dampens spreading and recoil. Using a simple scale analysis of energy balance, it was found that the maximum spread factor varies as Re1/5 when liquid viscosity is high and viscous effects govern the spreading behavior.

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