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

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.

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.

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.

scholarly journals Boussinesq modeling of surface waves due to underwater landslides

2013 ◽  
Vol 20 (3) ◽  
pp. 267-285 ◽  
Author(s):  
D. Dutykh ◽  
H. Kalisch
Keyword(s):  
Surface Waves ◽  
Shallow Water ◽  
Bottom Topography ◽  
Equations Of Motion ◽  
Boussinesq Equations ◽  
Time Dependent ◽  
Viscous Drag ◽  
Underwater Landslide ◽  
Landslide Mass ◽  
Run Up

Abstract. Consideration is given to the influence of an underwater landslide on waves at the surface of a shallow body of fluid. The equations of motion that govern the evolution of the barycenter of the landslide mass include various dissipative effects due to bottom friction, internal energy dissipation, and viscous drag. The surface waves are studied in the Boussinesq scaling, with time-dependent bathymetry. A numerical model for the Boussinesq equations is introduced that is able to handle time-dependent bottom topography, and the equations of motion for the landslide and surface waves are solved simultaneously. The numerical solver for the Boussinesq equations can also be restricted to implement a shallow-water solver, and the shallow-water and Boussinesq configurations are compared. A particular bathymetry is chosen to illustrate the general method, and it is found that the Boussinesq system predicts larger wave run-up than the shallow-water theory in the example treated in this paper. It is also found that the finite fluid domain has a significant impact on the behavior of the wave run-up.

Nonlinear dynamics of viscoelastic Taylor–Couette flow: effect of elasticity on pattern selection, molecular conformation and drag

2009 ◽  
Vol 620 ◽  
pp. 353-382 ◽  
Author(s):  
D. G. THOMAS ◽  
B. KHOMAMI ◽  
R. SURESHKUMAR
Keyword(s):  
Shear Rate ◽  
Linear Stability ◽  
Couette Flow ◽  
Drag Force ◽  
Molecular Conformation ◽  
Vortex Structures ◽  
Time Dependent ◽  
Pattern Selection ◽  
Stability Threshold ◽  
Flow Transitions

Three-dimensional and time-dependent simulations of viscoelastic Taylor–Couette flow of dilute polymer solutions are performed using a fully implicit parallel spectral time-splitting algorithm to discover flow patterns with various spatio-temporal symmetries, namely rotating standing waves (RSWs), disordered oscillations (DOs) and solitary vortex structures referred to as oscillatory strips (OSs) and diwhirls (DWs). A detailed account of the impact of flow transitions on molecular conformation and viscoelastic stress, velocity profiles, hydrodynamic drag force and energy spectra of time-dependent flow states is presented. Overall, predicted pattern selection and flow features compare very favourably with experimental observations. For elasticity number E, that signifies the ratio of elastic to viscous forces, >0.1, and when the shear rate (cylinder rotation speed) is increased above the linear stability threshold, the circular Couette flow (CCF) becomes unstable to RSWs which are characterized by a checkerboard-like pattern in the space–time plot of radial velocity, implying symmetry between inflow/outflow (I/O) regions. As the shear rate is further increased, perturbations that break the I/O symmetry are amplified leading to DOs and/or flame-like patterns with spectral mechanical energy transfer reminiscent of elastically induced low-Reynolds-number turbulence. However, when the shear rate is decreased from those at which such chaotic states are observed, the radially inward acting polymer body force created by flow-induced molecular stretching causes the development of narrow inflow regions surrounded by much broader weak outflow domains. This promotes the formation of solitary vortex structures, which can be stationary and axisymmetric (DWs) or time-dependent (OSs). The dynamics of the formation of these structures by merging and coalescence of vortex pairs and the implication of such events on instantaneous hydrodynamic force are studied. For O(1) values of E, OSs and DWs appear approximately at constant values of the We, defined as the ratio of polymer relaxation time to the inverse shear rate in the gap. As shear rate is decreased further, DWs decay to CCF although at We values less than the linear stability threshold. The flow transitions are hysteretic with respect to We, as evidenced by a plot of drag force versus We.

Magnetic manipulation on the unlabeled nonmagnetic particles

2019 ◽  
Vol 33 (07) ◽  
pp. 1950047 ◽  
Author(s):  
Yongqing He ◽  
Laan Luo ◽  
Shuang Huang
Keyword(s):  
Flow Rate ◽  
Magnetic Force ◽  
Opposite Polarity ◽  
Viscous Drag ◽  
Maximum Deviation ◽  
Magnetic Manipulation ◽  
Practical Applications ◽  
Viscous Drag Force ◽  
Flow Rate Range ◽  
Nonmagnetic Particles

This paper reports two basic microfluidic strategies for the magnetic manipulation of unlabeled nonmagnetic particles/cells. One is the deflection induced by a single magnet, and the other is the confusing effect produced by two magnets of opposite polarity. They can be combined into more completed particle manipulations like continuous flow separation, counting and detection, which are essential steps in biomedical applications. We experimentally studied the dynamics of 10.4 and 20 [Formula: see text]m nonmagnetic polystyrene particles within a flow rate range of 30, 50, 70 and 90 [Formula: see text]L/min in a straight channel. We defined the cross-section length that the particles occupy as the “particle bandwidth” to characterize the extent of deflection and focusing. To predict the trajectories of the particles, we established a simple theoretical model by considering the magnetic force and viscous drag force. Compared with the experimental results, the maximum deviation of the simulation is 9.28%. The influences of magnetic nanoparticle concentration, magnetic field parameters, size of microparticles and flow rate are systematically investigated. We also demonstrated that the effective deflection and focusing could be realized at low Fe3O4 nanoparticle concentrations, which means that this method can reduce the damage on cells in the practical applications.

scholarly journals Dynamics of photo-ablated carbon plasma in an inert gas atmosphere

1998 ◽  
Vol 16 (1) ◽  
pp. 31-38 ◽  
Author(s):  
T. Kerdja ◽  
S. Abdelli ◽  
E. H. Amara ◽  
D. Ghobrini ◽  
M. Si-Bachir ◽  
...  
Keyword(s):  
Wave Model ◽  
Inert Atmosphere ◽  
Viscous Drag ◽  
Laser Evaporation ◽  
Force Model ◽  
Plasma Dynamics ◽  
Gas Atmosphere ◽  
Viscous Drag Force ◽  
Swan Band ◽  
Two Stages

Time and space-resolved emission spectroscopy measurements were performed to investigate plasma dynamics during laser evaporation of a graphite target in an ambient inert atmosphere. Intense molecular emission is found to occur behind a front separating the plasma from the foreign gas. Two stages of expansion are found and are well described, using a viscous drag force model for the first one and a delayed ideal blast wave model for the second. The vibrational temperature estimated using the Swan band in helium at different pressures is presented.

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