Influence of Physical Parameters on the Collapse of a Spherical Bubble

2020 ◽  
Author(s):  
Bohua Sun
Keyword(s):  
Surface Tension ◽  
Physical Parameter ◽  
Pressure Difference ◽  
Bubble Formation ◽  
Bubble Collapse ◽  
Physical Parameters ◽  
Liquid Environment ◽  
Spherical Bubble ◽  
Maple Code ◽  
Surrounding Liquid

This paper examines the influence of physical parameters on the collapse dynamics of a spherical bubble filled with diatomic gas ($\kappa=7/5$). The present numerical investigation shows that each physical parameter affects the bubble collapse dynamics differently. After comparing the contribution of each physical parameter, it appears that, of all the parameters, the surrounding liquid environment affects the bubble collapse dynamics the most. Meanwhile, surface tension has the weakest influence and can be ignored in the bubble collapse dynamics. However, surface tension must be retained in the initial analysis since this, as well as the pressure difference jointly control initial bubble formation. As an essential part of this study, a general Maple code is provided.

Towards an Improved Megasonic Cleaning Process: Influence of Surface Tension on Bubble Activity in Acoustic Fields

2012 ◽  
Vol 195 ◽  
pp. 173-176
Author(s):  
Elisabeth Camerotto ◽  
Steven Brems ◽  
Marc Hauptmann ◽  
Jelle Lurquin ◽  
Herbert Struyf ◽  
...  
Keyword(s):  
Surface Tension ◽  
Semiconductor Industry ◽  
Surface Active Agent ◽  
Active Agent ◽  
Bubble Collapse ◽  
Physical Parameters ◽  
Particle Removal ◽  
Acoustic Fields ◽  
Produce Water ◽  
Megasonic Cleaning

Removal of particulate residues represents a very challenging step in current CMOS-technology nodes. The continued miniaturization and the introduction of novel materials in the semiconductor industry have resulted in very stringent requirements for device fabrication steps such as cleaning processes [. Physical forces, acting directly on the surface to be cleaned, are currently employed for delicate particle removal as an alternative to more aggressive chemistries [2]. High frequency ultrasounds (500 kHz 4 MHz), or megasonics, rely on the action of oscillating bubbles created during the ultrasonic agitation of the cleaning liquid. Strongly oscillating gas bubbles are able to generate shear forces, which are considered to be responsible for cleaning [3]. However, collapsing bubbles close to a surface can also produce water jets and shockwaves which lead to damage of fragile structures. Fundamental research is needed in order to overcome these issues by improving the understanding of the physical parameters playing a role in the acoustic cavitation of bubbles. This study reports the effects of lowering the surface tension of the liquid bulk on the bubble activity in the MHz range. A lower surface tension (45 mN/m) with respect to water (72 mN/m) is obtained by adding a non-ionic surface-active agent (TritonX-100). After fully characterizing its wettability, a cleaning solution containing surfactant is investigated under pulsed and continuous acoustic fields, for different acoustic amplitudes and gas concentrations. The aim is to increase bubble activity while reducing the strength of the bubble collapse. The results obtained can be useful in tuning megasonic cleaning systems towards more efficient processes.

The Behavior of a Spherical Bubble in the Vicinity of a Solid Wall

1968 ◽  
Vol 90 (1) ◽  
pp. 75-89 ◽  
Author(s):  
A. Shima
Keyword(s):  
Surface Tension ◽  
Flow Velocity ◽  
Solid Wall ◽  
Bubble Surface ◽  
Bubble Collapse ◽  
Theoretical Treatment ◽  
Bubble Shape ◽  
Spherical Bubble ◽  
Numerical Examples ◽  
Impulse Pressure

The behavior of a spherical bubble as it collapses in the vicinity of a solid wall was theoretically analyzed, in terms of the effect of compressibility, viscosity, surface tension, and gravity being ignored, and the gas in the bubble following the adiabatic law of compression assumed. Numerical examples obtained by applying the theoretical treatment are given for the change in time of bubble shape as it collapses, the impulse pressure occurring during bubble collapse, and the flow velocity at the bubble surface.

The nucleation of cavities at grain boundaries

1987 ◽  
Vol 45 ◽  
pp. 288-291
Author(s):  
P. J. Goodhew
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Grain Boundaries ◽  
Radiation Damage ◽  
Impurity Concentration ◽  
Driving Force ◽  
Nucleation And Growth ◽  
Phase Boundaries ◽  
Cavity Nucleation ◽  
Spherical Bubble

Cavity nucleation and growth at grain and phase boundaries is of concern because it can lead to failure during creep and can lead to embrittlement as a result of radiation damage. Two major types of cavity are usually distinguished: The term bubble is applied to a cavity which contains gas at a pressure which is at least sufficient to support the surface tension (2g/r for a spherical bubble of radius r and surface energy g). The term void is generally applied to any cavity which contains less gas than this, but is not necessarily empty of gas. A void would therefore tend to shrink in the absence of any imposed driving force for growth, whereas a bubble would be stable or would tend to grow. It is widely considered that cavity nucleation always requires the presence of one or more gas atoms. However since it is extremely difficult to prepare experimental materials with a gas impurity concentration lower than their eventual cavity concentration there is little to be gained by debating this point.

Formation of Core-Shell Nanoparticles by Laser Ablation of Copper and Brass in Liquids

2005 ◽  
Vol 106 ◽  
pp. 23-26 ◽  
Author(s):  
P.V. Kazakevich ◽  
A.V. Simakin ◽  
V.V. Voronov ◽  
G.A. Shafeev ◽  
D. Starikov ◽  
...  
Keyword(s):  
Core Shell ◽  
Copper Vapour Laser ◽  
Shell Nanoparticles ◽  
Liquid Environment ◽  
Pulsed Nd:Yag Laser ◽  
Plasmon Peak ◽  
Average Size ◽  
Core Shell Nanoparticles ◽  
20 Nm ◽  
Surrounding Liquid

Experimental results are presented on the ablation of copper and brass targets in a liquid environment: ethanol, acetone, or water by irradiation with either a pulsed copper vapour laser (0.51 μm) or a pulsed Nd:YAG laser (1.06 μm). The ablated material was ejected into the surrounding liquid as nanoparticles of average size 20 nm. The nanoparticle composition depends on the nature of the liquid. Ablation of 60%Cu, 40%Zn brass in ethanol results in formation of core-shell nanoparticles. Brass nanoparticles were characterized by a well-defined plasmon peak at 510-520 nm.

A Method for Identifying Parameters of Mechanical Joints

1990 ◽  
Vol 57 (2) ◽  
pp. 337-342 ◽  
Author(s):  
J. Wang ◽  
P. Sas
Keyword(s):  
Physical Parameter ◽  
Mechanical Systems ◽  
Degree Of Freedom ◽  
Modal Testing ◽  
Physical Parameters ◽  
Mechanical Joints ◽  
Joint Parameters

A method for identifying the physical parameters of joints in mechanical systems is presented. In the method, a multi-d.o.f. (degree-of-freedom) system is transformed into several single d.o.f. systems using selected eigenvectors. With the result from modal testing, each single d.o.f. system is used to solve for a pair of unknown physical parameters. For complicated cases where the exact eigenvector cannot be obtained, it will be proven that a particular physical parameter has a stationary value in the neighborhood of an eigenvector. Therefore, a good approximation for a joint physical parameter can be obtained by using an approximate eigenvector and the exact value for the joint parameters can be reached by carrying out this process in an iterative way.

Gas diffusion from ascending gas bubbles

1969 ◽  
Vol 35 (4) ◽  
pp. 711-719 ◽  
Author(s):  
Paul H. Leblond
Keyword(s):  
Surface Tension ◽  
Gas Exchange ◽  
Gas Bubbles ◽  
Gas Diffusion ◽  
Gas Pressure ◽  
Pressure Balance ◽  
Spherical Bubble ◽  
Gas Leakage ◽  
Quantitative Results ◽  
Ascent Velocity

General qualitative rules are derived for the behaviour of the volume of an ascending spherical bubble and of the gas pressure within it. Three modes of behaviour are discerned, corresponding to as many possible orderings of the relative influences of ascent velocity, gas leakage and surface tension on the volume and the pressure balance. These general results are nearly independent of the particular forms of the ascent velocity and gas exchange functions. Quantitative results are presented for the Stokes law régime.

scholarly journals Asymptotic Analysis of Nonlinear Resonance Interaction of Capillary Waves of Arbitrary Symmetry on Moving Charged Jet at Multimode Initial Deformation

2021 ◽  
Vol 57 (3) ◽  
pp. 72-82
Author(s):  
S. Shiryaeva ◽  
Keyword(s):  
Surface Tension ◽  
Nonlinear Resonance ◽  
Radial Electric Field ◽  
Resonant Interaction ◽  
Capillary Waves ◽  
Initial Deformation ◽  
Physical Parameters ◽  
Dimensionless Amplitude ◽  
Material Environment ◽  
The Waves

The problem of research of a nonlinear resonance between capillary waves on a surface of the charged jet at multimode initial deformation moving regarding the material environment is considered. It is shown in analytical asymptotic calculations of the second order on the dimensionless amplitude of oscillations that on a surface of a jet an internal nonlinear resonant interaction of capillary waves of any symmetry, both degenerate and secondary combinational, takes place. Positions of resonances depend on physical parameters of the system: the values of the coefficient of a surface tension and of the radial electric field at a surface of a jet, the velocity of its movement regarding the material environment, the values of the wave and azimuthal numbers of the interacting waves, a range of the waves defining initial deformation.

scholarly journals Marangoni Convection of Dust Particles in the Boundary Layer of Maxwell Nanofluids with Varying Surface Tension and Viscosity

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1072
Author(s):  
Khaled S. AlQdah ◽  
Naseer M. Khan ◽  
Habib Ben Bacha ◽  
Jae-Dong Chung ◽  
Nehad Ali Shah
Keyword(s):  
Surface Tension ◽  
Nusselt Number ◽  
Temperature Distribution ◽  
Dust Particles ◽  
Physical Parameters ◽  
Temperature Dependent Viscosity ◽  
Liquid Phases ◽  
Variable Surface ◽  
Basic Equations ◽  
Dependent Viscosity

The flow of nanofluids is very important in industrial refrigeration systems. The operation of nuclear reactors and the cooling of the entire installation to improve safety and economics are entirely dependent on the application of nanofluids in water. Therefore, a model of Maxwell’s dusty nanofluid with temperature-dependent viscosity, surface suction and variable surface tension under the action of solar radiation is established. The basic equations of momentum and temperature of the dust and liquid phases are solved numerically using the MATLAB bvp4c scheme. In the current evaluation, taking into account variable surface tension and varying viscosity, the effect of dust particles is studied by immersing dust particles in a nanofluid. Qualitative and quantitative discussions are provided to focus on the effect of physical parameters on mass and heat transfer. The propagation results show that this mixing effect can significantly increase the thermal conductivity of nanofluids. With small changes in the surface tension parameters, a stronger drop in the temperature distribution is observed. The suction can significantly reduce the temperature distribution of the liquid and dust phases. The stretchability of the sheet is more conducive to temperature rise. The tables are used to explain how physical parameters affect the Nusselt number and mass transfer. The increased interaction of the liquid with nanoparticles or dust particles is intended to improve the Nusselt number. This model contains features that have not been previously studied, which stimulates demand for this model among all walks of life now and in the future.

Identification of Physical Helicopter Models Using Subspace Identification

2020 ◽  
Vol 65 (2) ◽  
pp. 1-14
Author(s):  
Sevil Avcıoğlu ◽  
Ali Türker Kutay ◽  
Kemal Leblebicioğlu
Keyword(s):  
Parameter Estimation ◽  
State Space ◽  
Nonlinear Optimization ◽  
Physical Parameter ◽  
Test Data ◽  
Flight Test ◽  
The State ◽  
Physical Parameters ◽  
Subspace Identification ◽  
Study Results

Subspace identification is a powerful tool due to its well-understood techniques based on linear algebra (orthogonal projections and intersections of subspaces) and numerical methods like singular value decomposition. However, the state space model matrices, which are obtained from conventional subspace identification algorithms, are not necessarily associated with the physical states. This can be an important deficiency when physical parameter estimation is essential. This holds for the area of helicopter flight dynamics, where physical parameter estimation is mainly conducted for mathematical model improvement, aerodynamic parameter validation, and flight controller tuning. The main objective of this study is to obtain helicopter physical parameters from subspace identification results. To achieve this objective, the subspace identification algorithm is implemented for a multirole combat helicopter using both FLIGHTLAB simulation and real flight-test data. After obtaining state space matrices via subspace identification, constrained nonlinear optimization methodologies are utilized for extracting the physical parameters. The state space matrices are transformed into equivalent physical forms via the "sequential quadratic programming" nonlinear optimization algorithm. The required objective function is generated by summing the square of similarity transformation equations. The constraints are selected with physical insight. Many runs are conducted for randomly selected initial conditions. It can be concluded that all of the significant parameters can be obtained with a high level of accuracy for the data obtained from the linear model. This strongly supports the idea behind this study. Results for the data obtained from the nonlinear model are also evaluated to be satisfactory in the light of statistical error analysis. Results for the real flight-test data are also evaluated to be good for the helicopter modes that are properly excited in the flight tests.

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