The motion of a solid sphere suspended by a Newtonian or viscoelastic jet

This paper describes experimental observations of a solid sphere suspended by a vertical or inclined jet. A laminar Newtonian jet is able to suspend a sphere only through viscous entrainment at low Reynolds numbers (Re ~ 10). A turbulent Newtonian jet (Re ~ 104) attracts a sphere that is sufficiently large but rejects smaller ones. The Coanda effect is responsible for steady suspension of solid spheres even in highly slanted jets. Anomalous rotation, opposite to the direction of the local shear, occurs under certain conditions, and its physical mechanism cannot be explained based on available information. A viscoelastic laminar jet is narrower than a comparable Newtonian one and it can suspend spheres at Reynolds numbers in the hundreds, precisely the Re range in which a Newtonian jet fails to suspend a sphere. It is suggested that the contrast between laminar Newtonian and viscoelastic jets may be related to a reversal in the pressure distribution on the surface of the sphere caused by non-Newtonian normal stresses. Flow visualization provides insights into the flow field in the jet and around the solid sphere.

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Flow Field around NACA0012 Airfoil in Low Reynolds Numbers

JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ◽

10.2322/jjsass.64.123 ◽

2016 ◽

Vol 64 (2) ◽

pp. 123-130 ◽

Cited By ~ 1

Author(s):

Tomohisa OHTAKE

Keyword(s):

Flow Field ◽

Reynolds Numbers ◽

Low Reynolds Numbers ◽

Naca0012 Airfoil ◽

Low Reynolds

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Suppression of vortex shedding behind a circular cylinder by another control cylinder at low Reynolds numbers

Journal of Fluid Mechanics ◽

10.1017/s002211200600382x ◽

2007 ◽

Vol 573 ◽

pp. 171-190 ◽

Cited By ~ 36

Author(s):

A. DIPANKAR ◽

T. K. SENGUPTA ◽

S. B. TALLA

Keyword(s):

Vortex Shedding ◽

Physical Mechanism ◽

Grid Method ◽

Reynolds Numbers ◽

Accurate Solution ◽

Navier Stokes ◽

Navier Stokes Equation ◽

Low Reynolds Numbers ◽

Low Reynolds ◽

Control Cylinder

Vortex shedding behind a cylinder can be controlled by placing another small cylinder behind it, at low Reynolds numbers. This has been demonstrated experimentally by Strykowski & Sreenivasan (J. Fluid Mech. vol. 218, 1990, p. 74). These authors also provided preliminary numerical results, modelling the control cylinder by the innovative application of boundary conditions on some selective nodes. There are no other computational and theoretical studies that have explored the physical mechanism. In the present work, using an over-set grid method, we report and verify numerically the experimental results for flow past a pair of cylinders. Apart from providing an accurate solution of the Navier–Stokes equation, we also employ an energy-based receptivity analysis method to discuss some aspects of the physical mechanism behind vortex shedding and its control. These results are compared with the flow picture developed using a dynamical system approach based on the proper orthogonal decomposition (POD) technique.

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Flow field studies behind a wing at low Reynolds numbers

10.2514/6.1990-1471 ◽

1990 ◽

Cited By ~ 1

Author(s):

ALLEN WINKELMANN

Keyword(s):

Flow Field ◽

Field Studies ◽

Reynolds Numbers ◽

Low Reynolds Numbers ◽

Low Reynolds

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Numerical Study of Winglet at Low Reynolds Numbers

Volume 1B, Symposia: Fluid Machinery; Fluid Power; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Fundamental Issues and Perspectives in Fluid Mechanics ◽

10.1115/fedsm2013-16048 ◽

2013 ◽

Author(s):

Sina Pooladsanj ◽

Mehran Tadjfar

Keyword(s):

Aspect Ratio ◽

Flow Field ◽

Vortex Flow ◽

Numerical Study ◽

Reynolds Numbers ◽

Flow Zone ◽

Low Reynolds Numbers ◽

Structured Grid ◽

Flow Field Characteristics ◽

Wing Aspect Ratio

A numerical study has been performed to evaluate the aerodynamics coefficients of a winglet in the range of Reynolds numbers below 30,000. In this study some parameters on winglet design have been considered. The effect of winglet-tip airfoil thickness has been investigated on aerodynamics coefficients. In order to explore this effect, two different airfoils (NACA0002 and NACA0012) were employed at the winglet-tip. The influence of varying the winglet connection angle to the wing on aerodynamics coefficients and flow field characteristics in the vortex flow zone such as; circulation magnitude and vorticity magnitude in the vortex core have been studied. Six connection angles including 20°, 30°, 40°, 50°, 60° and 70° have been studied. Negative values of these angles have also been considered. In addition, the effect of changing wing aspect ratio on aerodynamics coefficients has been investigated. To solve the flow field around the studied geometry a fully structured grid was used which consists of 84 blocks.

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Experiments on the Flow Field and Acoustic Properties of a Mach Number 0.8 Jet at Low Reynolds Numbers

13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference) ◽

10.2514/6.2007-3662 ◽

2007 ◽

Author(s):

H Slot ◽

B. Boersma ◽

Peter Moore

Keyword(s):

Mach Number ◽

Flow Field ◽

Reynolds Numbers ◽

Acoustic Properties ◽

Low Reynolds Numbers ◽

Low Reynolds

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Two-Dimensional Unsteady Viscous Flows

Volume 7B: Ocean Engineering ◽

10.1115/omae2017-62465 ◽

2017 ◽

Author(s):

Jian-Jun Shu

Keyword(s):

Circular Cylinder ◽

Flow Field ◽

Hydrodynamic Force ◽

Viscous Flows ◽

Reynolds Numbers ◽

Fundamental Solutions ◽

Time Dependent ◽

Two Dimensional ◽

Low Reynolds Numbers ◽

Rotational Motions

A number of new closed-form fundamental solutions for the two-dimensional generalized unsteady Oseen and Stokes flows associated with arbitrary time-dependent translational and rotational motions have been developed. As an example of application, the hydrodynamic force acting on a circular cylinder translating in an unsteady flow field at low Reynolds numbers is calculated using the new generalized fundamental solutions.

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Digital image processing for quantification through full flow field tracing (FFFT) in narrow geometries at low Reynolds numbers

10.2514/6.1988-3781 ◽

1988 ◽

Cited By ~ 1

Author(s):

M. BRAUN ◽

C. BATUR ◽

G. KARAVELAKIS

Keyword(s):

Image Processing ◽

Flow Field ◽

Digital Image Processing ◽

Digital Image ◽

Reynolds Numbers ◽

Low Reynolds Numbers ◽

Low Reynolds

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Thin-Filament Pyrometry: A Novel Thermometry Technique for Combusting Flows

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.3240226 ◽

1989 ◽

Vol 111 (1) ◽

pp. 46-52 ◽

Cited By ~ 13

Author(s):

L. P. Goss ◽

V. Vilimpoc ◽

B. Sarka ◽

W. F. Lynn

Keyword(s):

Temperature Distribution ◽

Flow Field ◽

Diffusion Flame ◽

Thin Filament ◽

Large Scale ◽

Reynolds Numbers ◽

Temporal Response ◽

Ambient Conditions ◽

Low Reynolds Numbers ◽

Novel Technique

A novel technique is described for making temperature measurements in a combusting flow. The technique, Thin-Filament Pyrometry, is based on the blackbody emission of a small ceramic filament (15 μm), which is introduced into the flow field under study. Because the emission along the entire length of the filament is recorded, the complete spatial temperature distribution is measured. The temporal response of the filament is ∼ 700 Hz under ambient conditions. To demonstrate the capabilities of the technique in a combusting flow, a H2-N2 jet diffusion flame was studied. The evolution of the large-scale buoyancy-driven structures at low Reynolds numbers was followed by this technique.

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