Similarity in the three-dimensional penetration problem of solid bodies into an ideal incompressible fluid

1989 ◽  
Vol 29 (5) ◽  
pp. 718-722 ◽  
Author(s):  
F. M. Borodich
Keyword(s):  
Incompressible Fluid ◽  
Three Dimensional ◽  
Ideal Incompressible Fluid ◽  
Solid Bodies

Vortex ring eigen-oscillations as a source of sound

1997 ◽  
Vol 341 ◽  
pp. 19-57 ◽  
Author(s):  
V. F. KOPIEV ◽  
S. A. CHERNYSHEV
Keyword(s):  
Incompressible Fluid ◽  
Vortex Ring ◽  
Compressible Fluid ◽  
Acoustic Radiation ◽  
Three Dimensional ◽  
Sound Radiation ◽  
Complex Form ◽  
Ideal Incompressible Fluid ◽  
Dimensionless Frequency ◽  
Weakly Compressible

Two coupled problems are investigated: a complete description of long-wave vortex ring oscillations in an ideal incompressible fluid, and an examination of sound radiation by these oscillations in a weakly compressible fluid.The first part of the paper relates to the problem of eigen-oscillations of a thin vortex ring (μ[Lt ]1) in an ideal incompressible fluid. The solution of the problem is obtained in the form of an asymptotic expansion in the small parameter μ. The complete set of three-dimensional eigen-oscillations and axisymmetric modes (two-dimensional oscillations) is obtained. It is shown that, unlike the vortex column oscillations which have the form of simple angular harmonics, the majority of eigen-oscillations of a thin vortex ring have a more complex form which is a combination of two harmonics in the leading approximation. This leads to dramatic changes in the efficiency of sound radiation produced by modes of the vortex ring in comparison with the corresponding modes of the vortex column.In the second part of the paper the solution obtained is used to investigate the process of sound radiation by vortex perturbations in a weakly compressible fluid. The vortex ring eigen-oscillations are classified according to their sound radiation efficiency. It is shown that the modes with the dimensionless frequency ω≈1/2 radiate sound most efficiently. They are two isolated modes, two infinite families of Bessel modes and a set of axisymmetric modes. The frequencies of these modes are in the interval Δω=O(μ).The results obtained are compared with known experimental data on acoustic radiation of a turbulent vortex ring. Within the limits of the theory derived an explanation of the main characteristics of sound radiation is presented.

Optimal shape of slowly rising gas bubbles

2005 ◽  
Vol 83 (7) ◽  
pp. 761-766
Author(s):  
Alexei M Frolov
Keyword(s):  
Differential Equation ◽  
Ordinary Differential Equation ◽  
Incompressible Fluid ◽  
Three Dimensional ◽  
Gas Bubbles ◽  
Ideal Incompressible Fluid ◽  
Optimal Shape ◽  
Dimensional Problem ◽  
Optimal Form ◽  
One Dimensional

The variational optimal shape of slowly rising gas bubbles in an ideal incompressible fluid is determined. It is shown that the original three-dimensional problem can be reduced to a relatively simple one-dimensional (i.e., ordinary) differential equation. The solution of this equation allows one to obtain the variational optimal form of slowly rising gas bubbles. PACS No.: 47.55.Dz

scholarly journals Application of the erosion algorithm in modeling of structures behavior under impulse loads

2019 ◽  
Vol 221 ◽  
pp. 01003
Author(s):  
Pavel Radchenko ◽  
Stanislav Batuev ◽  
Andrey Radchenko
Keyword(s):  
Finite Element ◽  
High Velocity ◽  
Three Dimensional ◽  
Computer Software ◽  
Dynamic Loads ◽  
Complex Structures ◽  
Numerical Studies ◽  
Contact Surfaces ◽  
Fracture Of Materials ◽  
Solid Bodies

The paper presents results of applying approach to simulation of contact surfaces fracture under high velocity interaction of solid bodies. The algorithm of erosion -the algorithm of elements removing, of new surface building and of mass distribution after elements fracture at contact boundaries is consider. The results of coordinated experimental and numerical studies of fracture of materials under impact are given. Authors own finite element computer software program EFES, allowing to simulate a three-dimensional setting behavior of complex structures under dynamic loads, has been used for the calculations.

Consistent Hydrodynamic Mass for Parallel Prismatic Beams in a Fluid-Filled Container

1984 ◽  
Vol 106 (3) ◽  
pp. 270-275
Author(s):  
J. F. Loeber
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Incompressible Fluid ◽  
Finite Element Methods ◽  
Mass Matrix ◽  
Three Dimensional ◽  
Beam Length ◽  
Step Process ◽  
Beam Bending

In this paper, representation of the effects of incompressible fluid on the dynamic response of parallel beams in fluid-filled containers is developed using the concept of hydrodynamic mass. Using a two-step process, first the hydrodynamic mass matrix per unit (beam) length is derived using finite element methods with a thermal analogy. Second, this mass matrix is distributed in a consistent mass fashion along the beam lengths in a manner that accommodates three-dimensional beam bending plus torsion. The technique is illustrated by application to analysis of an experiment involving vibration of an array of four tubes in a fluid-filled cylinder.

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