Observations and Measurements of Flow in a Partially-Filled Horizontally Rotating Cylinder

1982 ◽  
Vol 104 (3) ◽  
pp. 363-366 ◽  
Author(s):  
R. F. Gans ◽  
S. M. Yalisove
Keyword(s):  
Laminar Flow ◽  
Parameter Space ◽  
Theoretical Calculations ◽  
Azimuthal Velocity ◽  
Rotating Cylinder ◽  
Velocity Versus ◽  
Two Parameter ◽  
Laminar State ◽  
Flow States

The authors report measurements of azimuthal velocity versus radius in a partially-filled horizontally rotating cylinder. These data confirm theoretical calculations for laminar flow. Three nonlaminar flow states are described and a map shows boundaries separating the laminar state, and two of the nonlaminar states, in a two parameter space.

scholarly journals Bifurcations of Oscillatory and Rotational Solutions of Double Pendulum with Parametric Vertical Excitation

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Michal Marszal ◽  
Krzysztof Jankowski ◽  
Przemyslaw Perlikowski ◽  
Tomasz Kapitaniak
Keyword(s):  
Periodic Solutions ◽  
Parameter Space ◽  
Double Pendulum ◽  
Bifurcation Diagrams ◽  
Kinematic Excitation ◽  
Vertical Excitation ◽  
Two Parameter ◽  
Domain Of Periodic Solutions

This paper investigates dynamics of double pendulum subjected to vertical parametric kinematic excitation. It includes detailed bifurcation diagrams in two-parameter space (excitation’s frequency and amplitude) for both oscillations and rotations in the domain of periodic solutions.

Laminar flow of power-law fluids past a rotating cylinder

2010 ◽  
Vol 165 (21-22) ◽  
pp. 1442-1461 ◽  
Author(s):  
Saroj K. Panda ◽  
R.P. Chhabra
Keyword(s):  
Laminar Flow ◽  
Power Law ◽  
Rotating Cylinder ◽  
Power Law Fluids

scholarly journals Analysis of static forces generated in-track on a railway sleeper resting on an elastic foundation due to structural imperfections using the PONTOS system

2019 ◽  
Vol 262 ◽  
pp. 11001
Author(s):  
Włodzimierz Andrzej Bednarek
Keyword(s):  
Theoretical Calculations ◽  
Railway Track ◽  
Bernoulli Beam ◽  
Main Concept ◽  
Field Investigations ◽  
Railway Sleeper ◽  
Foundation Parameters ◽  
Euler Bernoulli Beam ◽  
Structural Imperfections ◽  
Two Parameter

In the paper a considered railway sleeper was analysed as an Euler-Bernoulli beam and a Timoshenko beam of finite length resting on a oneand two-parameter foundation. The foundation parameters were determined based on a modified and analogue Vlasov soil model and field investigations. The main concept for the executed investigations was to induce an intentional imperfection in an actual railway track, propose a way of appropriate measurement (e.g. the PONTOS system by GOM mbh), and utilize author’s field investigations results to calibrate necessary parameters for theoretical calculations. An experimental formula describing the value of the force transferred from the rail to the railway sleeper on the grounds of the survey site caused by a locomotive was given. Furthermore, the deflection of the chosen railway sleeper due to the generated imperfection was analysed. Finally the objective of the present analysis was to resolve the calculations into the beam element such that the results can be utilised in computational railway practice. In the presented paper also the computational examples, diagrams and tables reflecting influence of analyzed parameters on obtained a CWR track’s displacements are enclosed.

Measurement of Surface Rheological Effects on a Rotating Flow

1981 ◽  
Vol 9 ◽  
Author(s):  
Roger F. Gans ◽  
Timothy J. Singler
Keyword(s):  
Theoretical Calculations ◽  
Azimuthal Velocity ◽  
Radial Variation ◽  
Distinct Difference ◽  
Bulk Liquid ◽  
Rotating Flow ◽  
Cylindrical Container ◽  
Air Core

ABSTRACTWe report measurement of azimuthal velocity as a function of radius near the boundary between a liquid annulus and (a) a rigid freely floating cylinder and (b) an air core contained in a rapidly rotating horizontal cylindrical container. Case (a) agrees with previous theoretical calculations and verifies the method. Case (b) demonstrates (1) that the interface can support stress and (2) that there is a distinct difference in the scale of radial variation in the bulk liquid from that observed in case (a).

Hopf Bifurcation of a Type of Neuron Model with Multiple Time Delays

2019 ◽  
Vol 29 (12) ◽  
pp. 1950163 ◽  
Author(s):  
Suqi Ma
Keyword(s):  
Hopf Bifurcation ◽  
Parameter Space ◽  
Time Delays ◽  
Neuron Model ◽  
Multiple Time ◽  
Multiple Time Delays ◽  
The Stability ◽  
Geometrical Scheme ◽  
Delay Differential ◽  
Two Parameter

By applying a geometrical scheme developed to tackle the eigenvalue problem of delay differential equations with multiple time delays, Hopf bifurcation of Hopfield neuron model is analyzed in two-parameter space. By the introduction of two new angles, the calculation of imaginary roots is carried out analytically and effectively. By increasing the parameter to cross over the Hopf bifurcation lines, the stability switching direction is confirmed. The method is a useful tool to show the partition of stable and unstable regions in two-parameter space and detect double Hopf bifurcation further. The typified dynamical behaviors based on nearby double Hopf points are analyzed by applying the normal form technique and center manifold method.

Instability and mode interactions in a differentially driven rotating cylinder

2002 ◽  
Vol 462 ◽  
pp. 383-409 ◽  
Author(s):  
J. M. LOPEZ ◽  
J. E. HART ◽  
F. MARQUES ◽  
S. KITTELMAN ◽  
J. SHEN
Keyword(s):  
Shear Layer ◽  
Azimuthal Velocity ◽  
Rotating Cylinder ◽  
Navier Stokes ◽  
Free Shear Layer ◽  
Wave State ◽  
Rotating Waves ◽  
Counter Rotation ◽  
Rotating Wave ◽  
Parameter Values

The flow in a completely filled rotating cylinder driven by the counter-rotation of the top endwall is investigated both numerically and experimentally. The basic state of this system is steady and axisymmetric, but has a rich structure in the radial and axial directions. The most striking feature, when the counter-rotation is sufficiently large, is the separation of the Ekman layer on the top endwall, producing a free shear layer that separates regions of flow with opposite senses of azimuthal velocity. This shear layer is unstable to azimuthal disturbances and a supercritical symmetry-breaking Hopf bifurcation to a rotating wave state results. For height-to-radius ratio of 0.5 and Reynolds number (based on cylinder radius and base rotation) of 1000, rotating waves with azimuthal wavenumbers 4 and 5 co-exist and are stable over an extensive range of the ratio of top to base rotation. Mixed modes and period doublings are also found, and a bifurcation diagram is determined. The agreement between the Navier–Stokes computations and the experimental measurements is excellent. The simulations not only capture the qualitative features of the multiple states observed in the laboratory, but also quantitatively replicate the parameter values over which they are stable, and produce accurate precession frequencies of the various rotating waves.

scholarly journals Experimental and numerical studies of an eastward jet over topography

2001 ◽  
Vol 438 ◽  
pp. 129-157 ◽  
Author(s):  
YUDONG TIAN ◽  
ERIC R. WEEKS ◽  
KAYO IDE ◽  
J. S. URBACH ◽  
CHARLES N. BAROUD ◽  
...  
Keyword(s):  
Parameter Space ◽  
Laboratory Experiments ◽  
Multiple Equilibria ◽  
Low Frequency ◽  
Zonal Flow ◽  
Azimuthal Velocity ◽  
Flow Patterns ◽  
Initial State ◽  
Similar Frequency ◽  
Zonal Flows

Motivated by the phenomena of blocked and zonal flows in Earth's atmosphere, we conducted laboratory experiments and numerical simulations to study the dynamics of an eastward jet flowing over wavenumber-two topography. The laboratory experiments studied the dynamical behaviour of the flow in a barotropic rotating annulus as a function of the experimental Rossby and Ekman numbers. Two distinct flow patterns, resembling blocked and zonal flows in the atmosphere, were observed to persist for long time intervals.Earlier model studies had suggested that the atmosphere's normally upstream- propagating Rossby waves can resonantly lock to the underlying topography, and that this topographic resonance separates zonal from blocked flows. In the annulus, the zonal flows did indeed have super-resonant mean zonal velocities, while the blocked flows appear subresonant. Low-frequency variability, periodic or irregular, was present in the measured time series of azimuthal velocity in the blocked regime, with dominant periodicities in the range of 6–25 annulus rotations. Oscillations have also been detected in zonal states, with smaller amplitude and similar frequency. In addition, over a large region of parameter space the two flow states exhibited spontaneous, intermittent transitions from the one to the other.We numerically simulated the laboratory flow geometry in a quasi-geostrophic barotropic model over a similar range of parameters. Both flow regimes, blocked and zonal, were reproduced in the simulations, with similar spatial and temporal characteristics, including the low-frequency oscillations associated with the blocked flow. The blocked and zonal flow patterns are present over wide ranges of forcing, topographic height, and bottom friction. For a significant portion of parameter space, both model flows are stable. Depending on the initial state, either the blocked or the zonal flow is obtained and persists indefinitely, showing the existence of multiple equilibria.

Complex force-constant dependence of elastic constants

1990 ◽  
Vol 68 (1) ◽  
pp. 14-22 ◽  
Author(s):  
H. A. Rafizadeh
Keyword(s):  
Elastic Constant ◽  
Force Constant ◽  
Elastic Constants ◽  
Theoretical Calculations ◽  
Linear Chain ◽  
Chain Model ◽  
Crystalline Solids ◽  
Young’S Moduli ◽  
Complex Functions ◽  
Two Parameter

Expressions for the inner and bare components of the elastic constants of crystalline solids are derived. The inner elastic constants are complex functions of the force constants and vanish only for centrosymmetric solids. Using a linear-chain model, the force-constant dependence of inner, bare, and total elastic constants is studied. The linear-chain model is also utilized in derivation of composition-dependent elastic constant equations. Single-parameter and two-parameter theoretical calculations are compared with the experimental composition-dependent Young's moduli of a number of metal–metalloid glasses.

Instantaneous Kinematics of a Tangent-Plane in Two-Parameter Space Motion

1994 ◽  
Vol 116 (1) ◽  
pp. 210-214
Author(s):  
D. P. Sathyadev ◽  
A. H. Soni
Keyword(s):  
Parameter Space ◽  
Tangent Plane ◽  
Plane Motion ◽  
Parameter Family ◽  
Spherical Image ◽  
Space Motion ◽  
Two Parameter

A tangent-plane undergoing two-parameter motion envelopes a surface called the tangent-plane envelope. Such surfaces can be considered as the envelope of a two-parameter family of planes or ∞2 family of planes. The properties of the tangent-plane motion are characterized through the properties of the spherical image of the normal to the surface it envelopes. This paper presents a methodology to locate a family of planes that envelope surfaces with similar characteristics.

A Simple Device for Preventing Turbulent Contamination on Swept Leading Edges

1965 ◽  
Vol 69 (659) ◽  
pp. 788-789 ◽  
Author(s):  
M. Gaster
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Laminar Flow ◽  
Leading Edge ◽  
Critical Value ◽  
Stagnation Line ◽  
Naturally Occurring ◽  
Swept Wings ◽  
Laminar State ◽  
Attachment Line

On unswept wings, or wings with small amounts of sweep, the favourable pressure gradient round the leading edge, where the flow is rapidly accelerated away from the stagnation line, ensures a certain amount of laminar flow, provided the wing surface is sufficiently smooth. On highly swept wings, however, it has been found that turbulent flow can exist on the attachment line itself and there are therefore no naturally occurring regions of laminar flow. This trouble arises from the turbulence at the root of the wing, which sweeps along the attachment line. If the Reynolds number of this turbulent attachment line boundary layer is greater than some critical value, the whole attachment line boundary layer remains turbulent and the complete wing is contaminated. But if the Reynolds number is below the critical value, the turbulence decays along the leading edge and the boundary layer on the attachment line reverts back to the laminar state. This situation arises when the leading edge radius is small and the wing is only slightly swept. The attachment line boundary layer Reynolds number, Rθ, is given by the following equation:

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