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).

Velocity, Potential, and Temperature Distributions in Molten Metals During Electromagnetic Stirring: Part I — Experimental Measurements

1999 ◽  
Author(s):  
Sayavur I. Bakhtiyarov ◽  
Ruel A. Overfelt ◽  
Amnon J. Meir ◽  
Paul G. Schmidt
Keyword(s):  
Experimental Technique ◽  
Magnetic Induction ◽  
Liquid Aluminum ◽  
Quadratic Function ◽  
Azimuthal Velocity ◽  
Cylindrical Container ◽  
Molten Metals ◽  
Angular Velocities ◽  
Probe Velocity ◽  
The Relationship

Abstract An experimental technique has been developed to measure the local velocity in molten metals. Couette flow of liquid aluminum, lead, tin and low melting alloy in cylindrical container was chosen for calibration of the experimental technique and the magnetic probe. Velocity and temperature profiles for liquid aluminum rotating in cylindrical container at different angular velocities are obtained for two different values of the depth. We determined that the velocity values increase with magnetic induction, and the relationship between the normalized azimuthal velocity and the magnetic induction can be expressed by quadratic function.

Magnetohydrodynamic co-rotating flow in a vertical cylindrical container

2016 ◽  
Vol 69 (9) ◽  
pp. 1051-1063 ◽  
Author(s):  
Brahim Mahfoud ◽  
Ali Bendjaghlouli ◽  
Rachid Bessaïh
Keyword(s):  
Rotating Flow ◽  
Cylindrical Container

scholarly journals Quasi-cylindrical approximation to the swirling flow in an atomizer chamber

2014 ◽  
Vol 758 ◽  
pp. 603-620
Author(s):  
F. J. Higuera ◽  
A. Pereña
Keyword(s):  
Boundary Layers ◽  
Flow Rate ◽  
Swirling Flow ◽  
Radial Pressure ◽  
Azimuthal Velocity ◽  
Liquid Sheet ◽  
Ekman Pumping ◽  
Air Core ◽  
Swirl Atomizer ◽  
Exit Orifice

AbstractA quasi-cylindrical approximation is used to analyse the axisymmetric swirling flow of a liquid with a hollow air core in the chamber of a pressure swirl atomizer. The liquid is injected into the chamber with an azimuthal velocity component through a number of slots at the periphery of one end of the chamber, and flows out as an annular sheet through a central orifice at the other end, following a conical convergence of the chamber wall. An effective inlet condition is used to model the effects of the slots and the boundary layer that develops at the nearby endwall of the chamber. An analysis is presented of the structure of the liquid sheet at the end of the exit orifice, where the flow becomes critical in the sense that upstream propagation of long-wave perturbations ceases to be possible. This analysis leads to a boundary condition at the end of the orifice that is an extension of the condition of maximum flux used with irrotational models of the flow. As is well known, the radial pressure gradient induced by the swirling flow in the bulk of the chamber causes the overpressure that drives the liquid towards the exit orifice, and also leads to Ekman pumping in the boundary layers of reduced azimuthal velocity at the convergent wall of the chamber and at the wall opposite to the exit orifice. The numerical results confirm the important role played by the boundary layers. They make the thickness of the liquid sheet at the end of the orifice larger than predicted by irrotational models, and at the same time tend to decrease the overpressure required to pass a given flow rate through the chamber, because the large axial velocity in the boundary layers takes care of part of the flow rate. The thickness of the boundary layers increases when the atomizer constant (the inverse of a swirl number, proportional to the flow rate scaled with the radius of the exit orifice and the circulation around the air core) decreases. A minimum value of this parameter is found below which the layer of reduced azimuthal velocity around the air core prevents the pressure from increasing and steadily driving the flow through the exit orifice. The effects of other parameters not accounted for by irrotational models are also analysed in terms of their influence on the boundary layers.

Diffusion driven rotating flow in a cylindrical container

1998 ◽  
Vol 126 (1-4) ◽  
pp. 45-57 ◽  
Author(s):  
R. Saci ◽  
P. G. Bellamy-Knights
Keyword(s):  
Rotating Flow ◽  
Cylindrical Container

A note on liquid vortex sloshing and Kelvin's equilibria

1990 ◽  
Vol 217 ◽  
pp. 241-248 ◽  
Author(s):  
Georgios H. Vatistas
Keyword(s):  
Cross Section ◽  
Equilibrium States ◽  
Stationary States ◽  
Cylindrical Container ◽  
Elliptical Cross ◽  
The Core ◽  
Spinning Disk ◽  
Air Core ◽  
Liquid Vortex ◽  
Lower Liquid

Observations of liquid vortex sloshing and Kelvin's equilibrium states were made inside a cylindrical container using a spinning disk near its base. Both steady and periodic free-surface sloshing phenomena were found to take place. During periodic sloshing, the air core sustained shape transformations, assuming an elliptical cross-section at the end, and then collapsed forming a pair of vortices. Kelvin's equilibrium states emerged at lower liquid levels. These were stable within an interval of rotational speeds. The bandwidth of stationary states decreased as the wavenumber (N) increased. For N greater than six, the states appeared critically stable. Between equilibria, unstable transitional regions were found to exist. As the liquid level was decreased, the core shape spectrum shifted towards smaller frequencies.

scholarly journals Mechanisms of transport enhancement for self-propelled nanoswimmers in a porous matrix

2021 ◽  
Vol 118 (27) ◽  
pp. e2101807118
Author(s):  
Haichao Wu ◽  
Benjamin Greydanus ◽  
Daniel K. Schwartz
Keyword(s):  
Theoretical Calculations ◽  
Porous Matrix ◽  
Bulk Liquid ◽  
Complex Environments ◽  
Void Space ◽  
Rate Determining Step ◽  
Brownian Particles ◽  
Directional Movement ◽  
Escape Process ◽  
Short Time

Micro/nanoswimmers convert diverse energy sources into directional movement, demonstrating significant promise for biomedical and environmental applications, many of which involve complex, tortuous, or crowded environments. Here, we investigated the transport behavior of self-propelled catalytic Janus particles in a complex interconnected porous void space, where the rate-determining step involves the escape from a cavity and translocation through holes to adjacent cavities. Surprisingly, self-propelled nanoswimmers escaped from cavities more than 20× faster than passive (Brownian) particles, despite the fact that the mobility of nanoswimmers was less than 2× greater than that of passive particles in unconfined bulk liquid. Combining experimental measurements, Monte Carlo simulations, and theoretical calculations, we found that the escape of nanoswimmers was enhanced by nuanced secondary effects of self-propulsion which were amplified in confined environments. In particular, active escape was facilitated by anomalously rapid confined short-time mobility, highly efficient surface-mediated searching for holes, and the effective abolition of entropic and/or electrostatic barriers at the exit hole regions by propulsion forces. The latter mechanism converted the escape process from barrier-limited to search-limited. These findings provide general and important insights into micro/nanoswimmer mobility in complex environments.

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.

Rotating Compressible Flow Over the Edge of a Finite Disk

1981 ◽  
Vol 48 (2) ◽  
pp. 249-254 ◽  
Author(s):  
M. Toren ◽  
A. Solan
Keyword(s):  
Compressible Flow ◽  
Temperature Difference ◽  
Incompressible Flow ◽  
Azimuthal Velocity ◽  
Ekman Layer ◽  
External Flow ◽  
Asymptotic Solutions ◽  
Rotating Flow ◽  
Outer Flow ◽  
Wide Range

Numerical and asymptotic solutions of the similarity equations governing the laminar compressible rotating flow near the edge of a finite disk are presented for a wide range of the Prandtl and Eckert numbers and the disk-to-external flow ratios of azimuthal velocity and temperature. By appropriate transformations, the compressible flow is reduced to a formulation similar to that of the incompressible flow. Wall heating and dissipation effects are shown to be equivalent to an increment of the velocity of the disk in the sense opposite to that of the outer flow. In the limit of small velocity or temperature difference between the disk and the outer flow, the solutions show how an Ekman layer is started at the edge.

XUV Absorption Spectra of Carbon Ions

1988 ◽  
Vol 102 ◽  
pp. 71-73
Author(s):  
E. Jannitti ◽  
P. Nicolosi ◽  
G. Tondello
Keyword(s):  
Absorption Spectra ◽  
Cross Section ◽  
Theoretical Calculations ◽  
Photoionization Cross Section ◽  
Carbon Ions

AbstractThe photoabsorption spectra of the carbon ions have been obtained by using two laser-produced plasmas. The photoionization cross-section of the CV has been absolutely measured and the value at threshold, σ=(4.7±0.5) × 10−19cm2, as well as its behaviour at higher energies agrees quite well with the theoretical calculations.

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