Experimental and analytical study on the stability of a bounded jet at low Reynolds numbers

by Juan Luis LВ©Д‘pez

Written in English
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Statementby Juan L. L©đpez
The Physical Object
Paginationxvi, 190 leaves :
Number of Pages190
ID Numbers
Open LibraryOL24597272M

Among the literature on acoustics the book of Pierce [] is an excellent introduction available for a low price from the Acoustical Society of America. In the preparation of the lecture notes we consulted various books which cover different aspects of the problem [15, 17, 19, 39, 50, 72, 89, 95, , , , , , , , , ]. The minimum Reynolds number on the stability curve on flat plate is. U cs 1 1 s = = ∞ ν δ Reδ, (6) where δ 1 is the displacement thickness. At lower Reynolds numbers all disturbances are dissipated but turbulence does not set in at that point. From this critical stability Reynolds number onwards the disturbance can grow but. A viscous silicon oil has been used in a Venturi geometry to explore the flow for Reynolds numbers ranging from R e = to R e = Special care has been taken to extract the maximum amount of dissolved air. At the lowest Reynolds numbers the cavities are steady and grow regularly with decreasing ambient pressure.   Stability bounds for explicit fractional-step schemes for the Navier–Stokes equations at high Reynolds number Computers & Fluids, Vol. 38, No. 6 Noise Generation Analysis of a Cylindrical Cavity by LES and Global Instability.

The Reynolds number (Re) helps predict flow patterns in different fluid flow low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers flows tend to be turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow. regurgitant jet, hugging the walls of the left atrium (LA) known as the Coanda e ect. certain cases the regurgitant jet hugs the wall of the heart's atrium as shown in Figure 1(c). These eccentric, wall-hugging, non-symmetric regurgitant jets have been observed at low Reynolds numbers [5, 6] and are said to undergo theCoandae ect[7,8].   Three-dimensional jet flows at high Reynolds (Re) numbers, namely over a million, have a significant importance in hydraulic e their importance, most of the previous investigations have been mainly focused only on jet flows with orders of magnitude lower Re numbers. We present the results of an experimental campaign and a high fidelity large-eddy simulation (LES) to study . An experimental study of oblique transition in plane Poiseuille flow. J. Fluid Mech. (Published) Experimental and theoretical stability investigations of plane liquid jets. Eur. J. Mech./Fluids 17 (Published) Experiments concerning the creation of streaky structures inside a plane water jet.

Turbulent boundary layer control at moderate Reynolds numbers by means of uniform blowing/suction 68th Annual Meeting of the APS Division of Fluid Dynamics, Nov. 22–24, , Boston, MA. 60 (Published) Flow separation delay on trucks A-pillars by means of Dielectric Barrier Discharge actuation Proc. 1st Int. Conf. Num. and Exp. Aerodyn. Although Eq. (2. 7a) is valid only for small Reynolds numbers (Re studies because it leads to the simple expression shown in Eq. (2. 1). For larger Reynolds numbers, extensive experimental determinations of the drag coefficient have been made (Schlichting, , or Fuchs, , p. 32). roborated through several studies, including the atomization of a liquid diesel jet at moderately low Reynolds number, Re = In a related study, Desjardins & Pitsch conducted detailed numerical simulations of primary atomization for several values of Reynolds and Weber numbers ( We present the first integrative computational fluid dynamics (CFD) study of near- and far-field aerodynamics in insect hovering flight using a biology-inspired, dynamic flight simulator. This simulator, which has been built to encompass multiple mechanisms and principles related to insect flight, is capable of `flying' an insect on the basis of realistic wing–body morphologies and kinematics.

Experimental and analytical study on the stability of a bounded jet at low Reynolds numbers by Juan Luis LВ©Д‘pez Download PDF EPUB FB2

Experimental and Analytical Study on the Stability of a Bounded Jet at Low Reynolds : Juan Luis Lopez. A series of steady flow experiments were described in which hydrodynamic factors are considered for the axisymmetric jet formed downstream of symmetric constrictions in circular pipes.

Results were obtained for several ratios of test section to constriction diameter, within a Reynolds number range from approximately 50 to The critical Reynolds number for onset of velocity Author: Juan Luis Lopez.

Experimental and analytical study on the stability of a bounded jet at low Reynolds numbers. By Juan Luis López. Abstract (Thesis) Thesis--University of Florida.(Bibliography) Includes bibliographical references (leaves )(Statement of Responsibility) by Juan L. López (leaves ) Author: Juan Luis López.

Multigrid cross-correlation digital particle image velocimetry (MCCDPIV) is used to investigate the stability and structure of low Reynolds number axisymmetric jets.

The in-plane velocities, out-of-plane vorticity and some of the components of the Reynolds stress tensor are measured. Two Reynolds numbers based on the orifice outlet diameter are examined ( and Cited by:   An experimental study of laminar jets sensitive to sound was conducted both in air and in water at low Reynolds numbers, the water jet permitting visual determination of a condition of neutral stability.

Plotted on a Reynolds‐Strouhal diagram, the neutral contours show the unstable region to be bounded at high Strouhal numbers and low Reynolds by: bounded jet, discharging steadily from a slot to stagnant bounded domain at different Reynolds numbers is considered.

The fluid dynamics of the velocity field is studied using contours and profiles. Also the centerline velocity decay is presented. 2 Problem Formulation Physics of Interest The geometry of interest is shown in Fig The air.

The shear layer development for a NACA airfoil at a low Reynolds number was investigated experimentally and numerically using large eddy simulation (LES). Two angles of attack (AOAs) were considered: 5 deg and 12 deg.

Experiments and numerics confirm that two flow regimes are present. Flow visualizations and phase-averaged particle image velocimetry (PIV) measurements of a jet in crossflow configuration at very low Reynolds numbers (Re j ≃ ) are performed in a water tunnel for jet-to-cross-stream velocity ratios R ranging from to The PIV vector fields and flow visualizations, carried out by injecting methylene blue dye and by the laser induced fluorescence (LIF.

The hyperbolic tangent shear layer and Bickley jet flows also show the stabilization by elasticity. We show the case p = 2 for both flows as a representative situation, for free surface and wall boundary results are displayed in Figs.

Fig. 5, Fig. 6, Fig. 7, Fig. plots show the imaginary part of the most unstable eigenvalue. 1 day ago  This paper explores the flow structure, mean/turbulent statistical characteristics of the vector field and entrainment of round jets issued from a smooth contracting nozzle at low nozzle exit velocities (– m/s).

The motivation of the study was to increase understand of the near field and get insights on how to control and reduce entrainment, particularly in applications that use jets.

Computational and experimental analysis of dynamics of drop formation Physics of Flu ( subject to appropriate initial and boundary conditions is solved in two dimensions to analyze the dynamics at finite Reynolds numbers. “ An experimental study of.

Experimental data from jet-engine tests have indicated that unsteady blade row interactions and separation can have a significant impact on the efficiency of low-pressure turbine stages.

The flow was observed to be steady and symmetric at low Reynolds numbers, with recirculating eddies downstream of each baffle. At a critical Reynolds number (based on channel width and cross-sectional mean velocity) of approximately the flow became asymmetric and unsteady.

Numerical and Experimental Flow Analysis of Moving Airfoils with Laminar Separation Bubbles. A study of long separation bubble on thick airfoils and its consequent effects. and Experimental Investigations of Equivalence Between Pitch and Plunge Motions for Airfoils at Low Reynolds Numbers.

ON THE STABILITY OF TWO-DIMENSIONAL PARALLEL FLOWS PART I—GENERAL THEORY* BY C. LIN Guggenheim Laboratory, California Institute of Technology 1.

Introduction. The study of the stability of laminar motion and its transition to turbulence dates back to the time of Helmholtz and Reynolds [46], and had.

A liquid being ejected from a nozzle emanates from it as discrete, uniformly sized drops when the flow rate is sufficiently low. In this paper, an experimental study is presented of the dynamics of a viscous liquid drop that is being formed directly at the tip of a vertical tube into ambient air.

The evolution in time of the drop shape and volume is monitored with a time resolution of 1/12 to. The study is motivated by the fact that most plane wall jet studies in the past have been conducted for plane wall jets in relatively large enclosures and/or with slot Reynolds numbers (i.e., Re based on inlet height) corresponding with a turbulent regime.

As opposed to many previous studies, this study will not only focus on the wall jet. liquid jet; and, in doing so, it also explains the un-derlying mechanism responsible for the generation of perturbations in this liquid jet.

The subject of stability analysis in liquid jets has been studied for over a century. It began with Lord Rayleigh’s linear analysis of an inviscid low speed jet with no gas [1].

Weber [2] expanded. and the jet Reynolds number. These study is useful in designing the more effective synthetic jet actuators which gives momentum transfer at low Reynolds number. Kral Linda. D, John F. Donovan, Alan B. Cain, and Andrew W. Cary [8] have carried out Numerical Simulation of Synthetic jet Actuators.

At low Reynolds numbers (Re. In the present paper, such an approach has been used, and results are presented for a row of inclined cylindrical holes at blowing ratios of and 1 and Reynolds numbers of 11,respectively, based on the jet velocity and hole diameter.

An Experimental and Analytical Investigation of Rectangular Synthetic Jets At low Reynolds numbers, synthetic jets show some devia- retical models of the external flow field of the synthetic jet, fol-8, However, at higher Reynolds numbers synthetic jets ex. Measurements on a wall-mounted NACA airfoil with an aspect ratio (AR) of operating in the low Reynolds number (, based on chord) regime were performed.

The acoustic signature of a controlled-diffusion airfoil immersed in a flow is experimentally characterized. Acoustic measurements have been carried out in an anechoic open-jet-wind-tunnel for low Reynolds numbers (from 5 × 10 4 to × 10 5) and several angles of with the NACA, the acoustic spectrum is dominated by discrete tones.

This book gathers contributions to the 21 st biannual symposium of the German Aerospace Aerodynamics Association (STAB) and the German Society for Aeronautics and Astronautics (DGLR). The individual chapters reflect ongoing research conducted by the STAB members in the field of numerical and experimental fluid mechanics and aerodynamics, mainly for (but not limited to).

The Principle of Dimensional Homogeneity Re p Re m V 0. p 0 (0 0. 1 ) or V p m/s cm/s Ans. C Fp C Fm or F p 10 7 N Ans. It would obviously be difficult to measure such a tiny drag force. Historically, the first person to write. spectrum presents a problem for the experimental or analytical methodolo- of this fundamental understanding together into one book and to present a unifying approach to the fundamental ideas of multiphase flows.

Conse- At high Reynolds number 53 At low Reynolds number 56 Molecular effects   An expansion in terms of the ratio λ of the characteristic crossflow velocity U ∞ to jet velocity U j, where λ=U ∞ /U j ≪1, is used to obtain a representation of the basic three-dimensional steady flow in the nearfield of a transverse jet at large Reynolds numbers and to study its dominant instability.

The inviscid vortex sheet analysis of Coelho and Hunt is extended so as to include. CiteScore: ℹ CiteScore: CiteScore measures the average citations received per peer-reviewed document published in this title.

CiteScore values are based on citation counts in a range of four years (e.g. ) to peer-reviewed documents (articles, reviews, conference papers, data papers and book chapters) published in the same four calendar years, divided by the number of.

On the basis of several numerical and experimental studies, the fact of the matter is that physically the flow in a driven cavity is not two‐dimensional above moderate Reynolds numbers.

However, there exist numerical solutions for two‐dimensional‐driven cavity flow at high Reynolds numbers. Transition in Wall-Bounded Shear Flows: The Role of Modern Stability Theory (P J Schmid) A Framework for Control of Fluid Flow (A Guégan et al.) Instabilities Near the Attachment-Line of Swept Wings (J Sesterhenn & R Friedrich) Experimental Study of Wall Turbulence: Implications for Control (I Marusic & N Hutchins).turbulent region of a round jet, using an improved implementation of Digital Particle Image Velocimetry (DPIV).

The two-dimensional flow field in planes normal and parallel to the axial velocity was measured at locations between 15 and 30 diameters downstream, for two Reynolds numbers of   [10] S.

K. Rathore and M. K. Das, "Comparison of two low-Reynolds number turbulence models for fluid flow study of wall bounded jets," International Journal of Heat and Mass Transfer, vol. 61, no. 1, pp.