The numerical study of viscous drag force influence on low-frequency surge motion of a semi-submersible in storm sea states

2020 ◽  
Vol 213 ◽  
pp. 107511 ◽  
Author(s):  
Shan Ma ◽  
De-kang Xu ◽  
Wen-yang Duan ◽  
Ji-kang Chen ◽  
Kang-ping Liao ◽  
...  
Keyword(s):  
Drag Force ◽  
Numerical Study ◽  
Low Frequency ◽  
Viscous Drag ◽  
Viscous Drag Force

scholarly journals Исследование реакции поверхности жидкости на импульсное воздействие наклонной газовой струи при малых числах Рэйнольдса

2022 ◽  
Vol 92 (2) ◽  
pp. 216
Author(s):  
А.П. Савенков ◽  
В.А. Сычёв
Keyword(s):  
Drag Force ◽  
Liquid Surface ◽  
Dynamic Properties ◽  
Liquid System ◽  
Gas Jet ◽  
Viscous Drag ◽  
Phase System ◽  
Two Phase ◽  
Automatic Control Theory ◽  
Viscous Drag Force

A mathematical description of the motion of a cavity on the liquid surface under an oblique action of a gas jet is obtained using the well-known expressions for the movement of a gas bubble in a liquid. The boundary of the viscous drag force domination over the form drag force is determined. The impingement of the gas jet on the liquid surface is considered as a dynamic object of the automatic control theory. It is found that the dynamic properties of the two-phase system "gas jet - liquid" are described by the integrator equations. Using a specially designed setup, the transient response of the "gas jet - liquid" system were experimentally obtained for the aerodynamic action at angles of 20º and 50º to the surfaces of liquids with the viscosities of 0.71 and 26.1 Pa•s (Reynolds number Re < 2). The research results are necessary for the analysis of the non-contact aerodynamic method of liquid viscosity measurements.

The viscous drag force on a spherical bubble with a time-dependent radius

1998 ◽  
Vol 10 (3) ◽  
pp. 550-554 ◽  
Author(s):  
Jacques Magnaudet ◽  
Dominique Legendre
Keyword(s):  
Drag Force ◽  
Time Dependent ◽  
Viscous Drag ◽  
Spherical Bubble ◽  
Viscous Drag Force

Structures of a Magnetorheological Fluid

2001 ◽  
Vol 15 (06n07) ◽  
pp. 851-858 ◽  
Author(s):  
G. L. Gulley ◽  
R. Tao
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Drag Force ◽  
Liquid State ◽  
Magnetorheological Fluid ◽  
Viscous Drag ◽  
Viscous Drag Force ◽  
Brownian Force ◽  
Dynamics Simulations ◽  
Two Parameters

Molecular dynamics simulations were carried out to find the underlying structures of a Magnetorheological (MR) fluid while taking into account dipolar forces, viscous drag, and the Brownian force. Three different structures were found: the bct lattice, chains, and a liquid state. The conditions under which these structures are found is based on two parameters A and B which are the ratios of the dipolar force to the viscous drag force and the Brownian force to the dipolar force respectively.

Numerical Study on Ventilated Cavitation Influenced by Injection of Drag-Reducing Solution

2017 ◽  
Author(s):  
Lu Wang ◽  
Ping-An Liu ◽  
Zhi-Ying Zheng ◽  
Yue Wang ◽  
Wei-Hua Cai ◽  
...  
Keyword(s):  
Numerical Study ◽  
Underwater Vehicle ◽  
Cavitation Number ◽  
Viscous Drag ◽  
Cavitating Flows ◽  
Cavity Shape ◽  
Partial Cavitation ◽  
Natural Cavitation ◽  
Viscous Drag Force ◽  
Multiphase Models

The influence of injection of drag-reducing solution on ventilated partial cavitation and supercavitation for an axisymmetric underwater vehicle is analyzed by numerical simulation. Turbulence, cavitation and multiphase models are SST k-ω, Schnerr-Sauer and Mixture models, respectively. The Cross viscosity equation is adopted to represent the fluid property of aqueous solution of drag-reducing additives. First of all, for non-cavitating conditions, the pressure distribution is obtained to determine the positions of injecting drag-reducing solution and ventilation. Then natural cavitation at different cavitation numbers is investigated for acquiring inception cavitation number. Finally, numerical simulations are conducted on the ventilated cavitating flows with and without the injection of drag-reducing solution at the cavitation number slightly smaller than the inception cavitation number (partial cavitation) and much smaller than the inception cavitation number (supercavitation). It is shown that for partial cavitation, the shape of cavity with the injection of drag-reducing solution is larger and the resistance of underwater vehicle decreases in comparison with the case without the injection of drag-reducing solution. However, for supercavitation, just viscous drag force obviously decreases, while cavity shape does not change.

Dark Matter: Could It Be Vacuum Viscosity?

2020 ◽  
Vol 13 (1) ◽  
pp. 47-57
Keyword(s):  
Dark Matter ◽  
Simple Model ◽  
Drag Force ◽  
Spiral Galaxies ◽  
Viscous Drag ◽  
Rotation Curves ◽  
The Galaxy ◽  
Viscous Drag Force ◽  
Matter Effect ◽  
Good Agreement

We test a hypothesis that stars located away from the center of the galaxy, moving under the effect of an emergent viscous drag force perpendicular to their velocities, might exhibit the behavior observed in the rotation curves of the spiral galaxies. We construct a simple model for such an assumption, then by using simple fitting technique, we are able to produce the rotation curves for a sample of 18 spiral galaxies. Results show good agreement with the observed rotation curves. The applicability of our hypothesis suggests that an emergent drag force perpendicular to the velocity of the stars might be the cause of the apparent dark matter effect.

Numerical study of the low-frequency atomic dynamics in a Lennard-Jones glass

1998 ◽  
Vol 77 (2) ◽  
pp. 473-484 ◽  
Author(s):  
M. Sampoli, P. Benassi, R. Dell'Anna,
Keyword(s):  
Numerical Study ◽  
Low Frequency ◽  
Lennard Jones

scholarly journals Electrodynamics of a magnet moving through a conducting pipe

2006 ◽  
Vol 84 (4) ◽  
pp. 253-271 ◽  
Author(s):  
M Hossein Partovi ◽  
Eliza J Morris
Keyword(s):  
Drag Force ◽  
Eddy Currents ◽  
Numerical Study ◽  
Full Range ◽  
Magnetic Behavior ◽  
Integral Form ◽  
Asymptotic Formulas ◽  
Pipe Material ◽  
Point Dipole ◽  
Axially Symmetric

The popular demonstration involving a permanent magnet falling through a conducting pipe is treated as an axially symmetric boundary-value problem. Specifically, Maxwell's equations are solved for an axially symmetric magnet moving coaxially inside an infinitely long, conducting cylindrical shell of arbitrary thickness at nonrelativistic speeds. Analytic solutions for the fields are developed and used to derive the resulting drag force acting on the magnet in integral form. This treatment represents a significant improvement over existing models, which idealize the problem as a point dipole moving slowly inside a pipe of negligible thickness. It also provides a rigorous study of eddy currents under a broad range of conditions, and can be used for magnetic braking applications. The case of a uniformly magnetized cylindrical magnet is considered in detail, and a comprehensive analytical and numerical study of the properties of the drag force is presented for this geometry. Various limiting cases of interest involving the shape and speed of the magnet and the full range of conductivity and magnetic behavior of the pipe material are investigated and corresponding asymptotic formulas are developed.PACS Nos.: 81.70.Ex, 41.20.–q, 41.20.Gz

scholarly journals Empirical Mode Reduction in a Model of Extratropical Low-Frequency Variability

2006 ◽  
Vol 63 (7) ◽  
pp. 1859-1877 ◽  
Author(s):  
D. Kondrashov ◽  
S. Kravtsov ◽  
M. Ghil
Keyword(s):  
Numerical Study ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
The Arctic ◽  
Reduced Model ◽  
The North ◽  
Low Frequency Variability ◽  
Intraseasonal Oscillations ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

Abstract This paper constructs and analyzes a reduced nonlinear stochastic model of extratropical low-frequency variability. To do so, it applies multilevel quadratic regression to the output of a long simulation of a global baroclinic, quasigeostrophic, three-level (QG3) model with topography; the model's phase space has a dimension of O(104). The reduced model has 45 variables and captures well the non-Gaussian features of the QG3 model's probability density function (PDF). In particular, the reduced model's PDF shares with the QG3 model its four anomalously persistent flow patterns, which correspond to opposite phases of the Arctic Oscillation and the North Atlantic Oscillation, as well as the Markov chain of transitions between these regimes. In addition, multichannel singular spectrum analysis identifies intraseasonal oscillations with a period of 35–37 days and of 20 days in the data generated by both the QG3 model and its low-dimensional analog. An analytical and numerical study of the reduced model starts with the fixed points and oscillatory eigenmodes of the model's deterministic part and uses systematically an increasing noise parameter to connect these with the behavior of the full, stochastically forced model version. The results of this study point to the origin of the QG3 model's multiple regimes and intraseasonal oscillations and identify the connections between the two types of behavior.

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