Nonlinear response of an ideal gas bubble to ambient pressure change in a quiescent fluid

1995 ◽  
Vol 12 (1) ◽  
pp. 66-71
Author(s):  
Jong-Wook Ha ◽  
Seung-Man Yang
Keyword(s):  
Nonlinear Response ◽  
Ambient Pressure ◽  
Pressure Change ◽  
Ideal Gas ◽  
Gas Bubble ◽  
Quiescent Fluid

Numerical Study of the Influence of Ambient Pressure on the Inerting Effect of an Aircraft Fuel Tank Inerting System

2014 ◽  
Vol 1061-1062 ◽  
pp. 1140-1143
Author(s):  
Dong Jie Liu
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Numerical Study ◽  
Ambient Pressure ◽  
Ideal Gas ◽  
Fuel Tank ◽  
Dissolved Oxygen Concentration ◽  
State Equations ◽  
Aircraft Fuel ◽  
Inerting System

The numerical study of the influence of the ambient pressure of the fuel tank on the inerting effect of an aircraft fuel tank inerting system was carried out. The mathematical model of ullage equilibrium oxygen concentration has been established using the differential time calculation method based on the mass conservation and ideal gas state equations. The variations of ullage oxygen concentration and dissolved oxygen concentration in the fuel with time under different working conditions have been obtained. The results have shown that the as the ambient pressure of the fuel tank became lower, the speed of the decreasing of oxygen concentration of the fuel tank ullge and the dissolved oxygen concentration of the fuel was slower.

Growth of gas bubbles in the biotissues with convective acceleration

2014 ◽  
Vol 07 (06) ◽  
pp. 1450072 ◽  
Author(s):  
S. A. Mohammadein ◽  
K. G. Mohamed
Keyword(s):  
Concentration Distribution ◽  
Bubble Dynamics ◽  
Ambient Pressure ◽  
Growth Stages ◽  
Gas Bubble ◽  
Bubble Motion ◽  
Dissolved Gas ◽  
Diffusion Limited ◽  
The Mathematical Model ◽  
Dominant Parameter

This paper presents formulae and explanation about the growth of a convective gas bubble in the blood and other tissues of divers who surface too quickly, concentration distribution around the growing bubble is also presented. The formulae are valid all over the growth stages, i.e. under variable ambient pressure while the diver is ascending, and under constant ambient pressure at diving stops or at sea level. The mathematical model is solved analytically by using the method of combined variables. The growth process is affected by tissue diffusivity, concentration constant and the initial void fraction, which is the dominant parameter. Results show that, the time of the complete growth, in the convective growth model, is shorter than those earlier presented by Mohammadein and Mohamed [Concentration distribution around a growing gas bubble in tissue, Math. Biosci.225(1) (2010) 11–17] and Srinivasan et al. [Mathematical models of diffusion-limited gas bubble dynamics in tissue, J. Appl. Physiol.86 (1999) 732–741] for the growth of a stationary gas bubble, this explains the effect of bubble motion on consuming the oversaturated dissolved gas from the tissue into growing bubble which leads to increment in the growth rate to be more than those presented in the previous stationary models.

Nonlinear effects in the dynamics of shape and volume oscillations for a gas bubble in an external flow

1993 ◽  
Vol 247 ◽  
pp. 417-454 ◽  
Author(s):  
S. M. Yang ◽  
Z. C. Feng ◽  
L. G. Leal
Keyword(s):  
Pressure Distribution ◽  
Pressure Pulse ◽  
Small Deformation ◽  
Resonant Interaction ◽  
Gas Bubble ◽  
Mean Flow ◽  
Resonant Interactions ◽  
Deformation Problem ◽  
Deformed Bubble ◽  
Quiescent Fluid

This paper considers the dynamics of a gas bubble in response to either a pressure pulse or a pressure step at t = 0, both in the presence and absence of a mean flow. Our work utilizes small-deformation, domain perturbation analysis carried to second and higher order in the amplitude of deformation, ε. In the absence of a mean flow, our analysis of the small deformation problem for an initial impulsive perturbation of the bubble volume and shape is closely related to recently published work by Longuet-Higgins on the time-dependent oscillations of an initially deformed bubble in a quiescent fluid. However, in the presence of a mean flow which deforms the bubble, the bubble response to pressure changes is more complex. Specifically, the present analysis identifies a number of different mechanisms for resonant interaction between shape deformation modes and the volume or radial breathing mode of oscillation. This includes not only a fundamental change in the resonant interactions at 0(ε2) - where resonant interaction is also found in the absence of mean flow – but resonant interactions also at the level of 0(ε3/2;) which are not present without the mean flow. On the other hand, the bubble dynamics in response to a step change in the pressure distribution in a quiescent fluid exhibits similar resonant interactions at 0(ε2) to those obtained for a pressure pulse in the presence of mean flow because the bubble oscillates around a non-spherical steady-state shape owing to the non-uniform pressure distribution on the bubble surface in both the cases.

Mathematical Model of Gas Bubble Evolution in a Straight Tube

1999 ◽  
Vol 121 (5) ◽  
pp. 505-513 ◽  
Author(s):  
D. Halpern ◽  
Y. Jiang ◽  
J. F. Himm
Keyword(s):  
Decompression Sickness ◽  
Ambient Pressure ◽  
Fluid Motion ◽  
Gas Bubbles ◽  
Coupled System ◽  
Bubble Surface ◽  
Inert Gas ◽  
Straight Tube ◽  
Gas Bubble ◽  
Bubble Evolution

Deep sea divers suffer from decompression sickness (DCS) when their rate of ascent to the surface is too rapid. When the ambient pressure drops, inert gas bubbles may form in blood vessels and tissues. The evolution of a gas bubble in a rigid tube filled with slowly moving fluid, intended to simulate a bubble in a blood vessel, is studied by solving a coupled system of fluid-flow and gas transport equations. The governing equations for the fluid motion are solved using two techniques: an analytical method appropriate for small nondeformable spherical bubbles, and the boundary element method for deformable bubbles of arbitrary size, given an applied steady flow rate. A steady convection-diffusion equation is then solved numerically to determine the concentration of gas. The bubble volume, or equivalently the gas mass inside the bubble for a constant bubble pressure, is adjusted over time according to the mass flux at the bubble surface. Using a quasi-steady approximation, the evolution of a gas bubble in a tube is obtained. Results show that convection increases the gas pressure gradient at the bubble surface, hence increasing the rate of bubble evolution. Comparing with the result for a single gas bubble in an infinite tissue, the rate of evolution in a tube is approximately twice as fast. Surface tension is also shown to have a significant effect. These findings may have important implications for our understanding of the mechanisms of inert gas bubbles in the circulation underlying decompression sickness.

scholarly journals In-Vivo Measurement of Ocular Deformation in Response to Ambient Pressure Modulation

2021 ◽  
Vol 9 ◽  
Author(s):  
Sabine Kling
Keyword(s):  
Ambient Pressure ◽  
Compressive Strain ◽  
Crystalline Lens ◽  
Pressure Change ◽  
Axial Displacement ◽  
Healthy Human ◽  
Cross Sectional ◽  
Mechanical Responses ◽  
Pressure Modulation

A novel approach is presented for the non-invasive quantification of axial displacement and strain in corneal and anterior crystalline lens tissue in response to a homogenous ambient pressure change. A spectral domain optical coherence tomography (OCT) system was combined with a custom-built set of swimming goggles and a pressure control unit to acquire repetitive cross-sectional scans of the anterior ocular segment before, during and after ambient pressure modulation. The potential of the technique is demonstrated in vivo in a healthy human subject. The quantification of the dynamic deformation response, consisting of axial displacement and strain, demonstrated an initial retraction of the eye globe (−0.43 to −1.22 nm) and a subsequent forward motion (1.99 nm) in response to the pressure change, which went along with a compressive strain induced in the anterior crystalline lens (−0.009) and a tensile strain induced in the cornea (0.014). These mechanical responses appear to be the result of a combination of whole eye motion and eye globe expansion. The latter simulates a close-to-physiologic variation of the intraocular pressure and makes the detected mechanical responses potentially relevant for clinical follow-up and pre-surgical screening. The presented measurements are a proof-of-concept that non-contact low-amplitude ambient pressure modulation induces tissue displacement and strain that is detectable in vivo with OCT. To take full advantage of the high spatial resolution this imaging technique could offer, further software and hardware optimization will be necessary to overcome the current limitation of involuntary eye motions.

561 Change of flattening and solidification behavior of single splat associated with ambient pressure change

2011 ◽  
Vol 2011.60 (0) ◽  
pp. _561-1_-_561-2_
Author(s):  
Yoshinobu EBISUNO ◽  
Kun YANG ◽  
Masahiro FUKUMOTO ◽  
Yoshiaki YASUI ◽  
Motohiro YAMADA
Keyword(s):  
Ambient Pressure ◽  
Pressure Change ◽  
Solidification Behavior

Contribution of Homogeneous Condensation Inside Cavitation Nuclei to Cavitation Inception

1986 ◽  
Vol 108 (4) ◽  
pp. 433-437
Author(s):  
Y. Matsumoto
Keyword(s):  
Ambient Pressure ◽  
Pressure Change ◽  
Numerical Results ◽  
Resolving Power ◽  
Scattering Method ◽  
Cavitation Inception ◽  
Homogeneous Condensation ◽  
Cavitation Nuclei ◽  
Surrounding Liquid ◽  
Good Agreement

The response of a small gas bubble, so-called cavitation nucleus, to the reduction of ambient pressure is investigated theoretically and experimentally. Numerical results show that the gas mixture inside the bubble expands adiabatically and the temperature of the mixture decreases rapidly at the first stage, however the temperature recovers soon to the surrounding liquid temperature by homogeneous condensation which forms a mist inside the bubble. Consequently, the bubble grows almost isothermally. Experiments have been performed using a hydro-shock tube. The radius of a small bubble has been measured by a light-scattering method whose time resolving power is one micro-second. The experimental results are found to be in good agreement with the numerical results calculated using the ambient pressure change measured in the test section.

About nonlinear nonspherical oscillations of a gas bubble in an incompressible ideal liquid

2003 ◽  
Vol 3 ◽  
pp. 178-194
Author(s):  
M.A. Ilgamov ◽  
E.Sh. Nasibullaeva ◽  
D.V. Kondtratyev
Keyword(s):  
Parametric Analysis ◽  
Applied Pressure ◽  
Pressure Change ◽  
Ideal Liquid ◽  
System Of Equations ◽  
Pressure Amplitude ◽  
Gas Bubble ◽  
Initial Radius ◽  
Initial Deviation ◽  
Incompressible Ideal Fluid

A comparative parametric analysis of a system of equations describing the nonspherical oscillations of a gas bubble in an incompressible ideal fluid is performed. The terms up to a second order of smallness in the amplitude of the surface perturbation are taking into account. Numerical calculations of this system of equations for various parameters (initial deviation from the sphere, pressure amplitude, initial radius) and for various laws of the applied pressure change are carried out.

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