scholarly journals Deformation of cylindrical cavities in plane-parallel potential flows with circulation and under the action of mass forces

2018 ◽  
pp. 207-214
Author(s):  
Н.Д. Байков ◽  
А.Г. Петров
Keyword(s):  
Boundary Element Method ◽  
Incompressible Fluid ◽  
Momentum Conservation ◽  
Quadrature Formulas ◽  
Heavy Fluid ◽  
Jet Formation ◽  
Perfect Incompressible Fluid ◽  
Plane Parallel ◽  
Potential Flows ◽  
Cylindrical Cavities

Рассматриваются задачи формирования кумулятивных струй в плоскопараллельных потенциальных течениях идеальной несжимаемой жидкости внутри цилиндрических полостей. На основе метода граничных элементов строится численный алгоритм решения. При аппроксимации используются квадратурные формулы без насыщения. Новизна работы заключается в исследовании потенциальных течений с ненулевой циркуляцией и выводе аналога закона сохранения импульса для таких течений. Кроме того, рассматривается задача всплытия полости в тяжелой жидкости. The problems of cumulative jet formation in plane-parallel potential flows of a perfect incompressible fluid within cylindrical cavities are considered. A new numerical algorithm is proposed on the basis of the boundary element method. The approximation is based on quadrature formulas without saturation. The novelty of this paper is to study the potential flows with nonzero circulation and to derive an analog of the momentum conservation law for such flows. The process of the cavity rise in a heavy fluid is also studied.

scholarly journals Gravitational and Dynamical Instabilities of a Decelerating Plane-Parallel Slab of Finite Thickness

1988 ◽  
Vol 101 ◽  
pp. 509-512
Author(s):  
G. Mark Voit
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Incompressible Fluid ◽  
Gravity Wave ◽  
Finite Thickness ◽  
Blast Waves ◽  
Plane Parallel ◽  
The Stability ◽  
Dynamical Instabilities ◽  
Symmetric And Antisymmetric Modes

AbstractIn order to explore how supernova blast waves might catalyze star formation, we investigate the stability of a slab of decelerating gas of finite thickness. We examine the early work in the field by Elmegreen and Lada and Elmegreen and Elmegreen and demonstrate that it is flawed. Contrary to their claims, blast waves can indeed accelerate the rate of star formation in the interstellar medium. Also, we demonstrate that in an incompressible fluid, the symmetric and antisymmetric modes in the case of zero acceleration transform continuously into Rayleigh-Taylor and gravity-wave modes as acceleration grows more important.

Secondary circulation in fluid flow

1951 ◽  
Vol 206 (1086) ◽  
pp. 374-387 ◽  
Keyword(s):  
Fluid Flow ◽  
Incompressible Fluid ◽  
Velocity Distribution ◽  
Secondary Flow ◽  
General Expression ◽  
Total Pressure ◽  
Secondary Circulation ◽  
Perfect Incompressible Fluid ◽  
Uniform Velocity ◽  
Circular Pipes

Secondary circulation appears after fluid with a non-uniform velocity distribution passes round a bend. It alters the character of the flow and is a source of loss. A general expression is developed for its change along a streamline in a perfect, incompressible fluid. The flow in bent circular pipes is analyzed and the theory is compared with experiments on bent pipes and rectangular ducts. In bends the secondary flow is not spiral but oscillatory, the direction of the circulation changing periodically. The theory shows that secondary circulation remains unchanged if streamlines are geodesics on surfaces of constant total pressure.

scholarly journals Modelling single- and tandem-bubble dynamics between two parallel plates for biomedical applications

2013 ◽  
Vol 716 ◽  
pp. 137-170 ◽  
Author(s):  
C.-T. Hsiao ◽  
J.-K. Choi ◽  
S. Singh ◽  
G. L. Chahine ◽  
T. A. Hay ◽  
...  
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Bubble Dynamics ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Design Tool ◽  
Parallel Plates ◽  
Jet Formation ◽  
Viscous Boundary Layer ◽  
Element Method

AbstractCarefully timed tandem microbubbles have been shown to produce directional and targeted membrane poration of individual cells in microfluidic systems, which could be of use in ultrasound-mediated drug and gene delivery. This study aims at contributing to the understanding of the mechanisms at play in such an interaction. The dynamics of single and tandem microbubbles between two parallel plates is studied numerically and analytically. Comparisons are then made between the numerical results and the available experimental results. Numerically, assuming a potential flow, a three-dimensional boundary element method (BEM) is used to describe complex bubble deformations, jet formation, and bubble splitting. Analytically, compressibility and viscous boundary layer effects along the channel walls, neglected in the BEM model, are considered while shape of the bubble is not considered. Comparisons show that energy losses modify the bubble dynamics when the two approaches use identical initial conditions. The initial conditions in the boundary element method can be adjusted to recover the bubble period and maximum bubble volume when in an infinite medium. Using the same conditions enables the method to recover the full dynamics of single and tandem bubbles, including large deformations and fast re-entering jet formation. This method can be used as a design tool for future tandem-bubble sonoporation experiments.

Hydrodynamic Issues of FLNG Systems

2013 ◽  
Author(s):  
Xiao-Bo Chen ◽  
Louis Diebold ◽  
Guillaume de-Hautecloque
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Wave Diffraction ◽  
Coupling Effect ◽  
Dynamic Effect ◽  
Complex Interaction ◽  
Liquid Motion ◽  
Potential Flows ◽  
Seakeeping Analysis ◽  
Element Method

Advanced hydrodynamic analyses of floating LNG terminals are presented in the paper. They consist of the complex interaction of multiple bodies and the coupling effect of seakeeping (wave diffraction and radiation around bodies) and sloshing (liquid motions in tanks). Based on the recent development to introduce the dissipation in potential flows and new formulations of boundary element method, the seakeeping analysis is enhanced to be able to make accurate predictions of gap resonances and major dynamic effect of liquid motion in tanks.

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