Some Experience on Particle Image Velocimetry of Near-Wall Shear Layers at Subsonic Velocities

2010 ◽  
Vol 5 (2) ◽  
pp. 55-68
Author(s):  
Andrey V. Boiko Boiko ◽  
Vasily N. Gorev ◽  
Aleksandr V. Dovgal ◽  
Aleksandr M. Sorokin ◽  
Hein Stefan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Shear Layers ◽  
Linear Instability ◽  
Wind Tunnel Testing ◽  
Mean Velocity ◽  
Separating Flow ◽  
Image Velocimetry ◽  
Near Wall

Experimental data on linear instability of the laminar separating flow and mean velocity characteristics of the turbulent boundary layer are reported. The results are obtained through wind-tunnel testing of Particle Image Velocimetry (PIV) performed at DLR, Goettingen. Details of the method, as applied to the above problems of fluid mechanics, are considered. The present findings seem helpful during experimental work on subsonic near-wall layers, when focusing on their instantaneous and time-mean velocity characteristics.

scholarly journals Experimental Validation of Falling Liquid Film Models: Velocity Assumption and Velocity Field Comparison

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1205
Author(s):  
Ruiqi Wang ◽  
Riqiang Duan ◽  
Haijun Jia
Keyword(s):  
Experimental Data ◽  
Particle Image Velocimetry ◽  
Velocity Field ◽  
Experimental Validation ◽  
Particle Image ◽  
Velocity Fields ◽  
Number Range ◽  
Comparison Results ◽  
Image Velocimetry ◽  
Experimental Particle

This publication focuses on the experimental validation of film models by comparing constructed and experimental velocity fields based on model and elementary experimental data. The film experiment covers Kapitza numbers Ka = 278.8 and Ka = 4538.6, a Reynolds number range of 1.6–52, and disturbance frequencies of 0, 2, 5, and 7 Hz. Compared to previous publications, the applied methodology has boundary identification procedures that are more refined and provide additional adaptive particle image velocimetry (PIV) method access to synthetic particle images. The experimental method was validated with a comparison with experimental particle image velocimetry and planar laser induced fluorescence (PIV/PLIF) results, Nusselt’s theoretical prediction, and experimental particle tracking velocimetry (PTV) results of flat steady cases, and a good continuity equation reproduction of transient cases proves the method’s fidelity. The velocity fields are reconstructed based on different film flow model velocity profile assumptions such as experimental film thickness, flow rates, and their derivatives, providing a validation method of film model by comparison between reconstructed velocity experimental data and experimental velocity data. The comparison results show that the first-order weighted residual model (WRM) and regularized model (RM) are very similar, although they may fail to predict the velocity field in rapidly changing zones such as the front of the main hump and the first capillary wave troughs.

scholarly journals AN ATHEROSCLEROTIC CORONARY ARTERY PHANTOM FOR PARTICLE IMAGE VELOCIMETRY

2011 ◽  
Author(s):  
Jean Brunette ◽  
Rosaire Mongrain ◽  
Rosaire Mongrain ◽  
Adrian Ranga ◽  
Adrian Ranga ◽  
...  
Keyword(s):  
Experimental Data ◽  
Particle Image Velocimetry ◽  
Heart Attack ◽  
Computational Models ◽  
Particle Image ◽  
Flow Analysis ◽  
Novel Technique ◽  
Image Velocimetry ◽  
Inflammatory Processes ◽  
Injection Molded

Myocardial infarction, also known as a heart attack, is the single leading cause of death in North America. It results from the rupture of an atherosclerotic plaque, which occurs in response to both mechanical stress and inflammatory processes. In order to validate computational models of atherosclerotic coronary arteries, a novel technique for molding realistic compliant phantom featuring injection-molded inclusions and multiple layers has been developed. This transparent phantom allows for particle image velocimetry (PIV) flow analysis and can supply experimental data to validate computational fluid dynamics algorithms and hypothesis.

An Experimental Investigation of Turbulent Drag Reduction in Concentric Annulus Using Particle Image Velocimetry Technique

2013 ◽  
Author(s):  
Fabio Ernesto Rodriguez Corredor ◽  
Majid Bizhani ◽  
Ergun Kuru
Keyword(s):  
Particle Image Velocimetry ◽  
Turbulent Flow ◽  
Drag Reduction ◽  
Particle Image ◽  
Reynolds Shear Stress ◽  
Polymer Concentration ◽  
Mean Flow ◽  
Flow Loop ◽  
Mean Velocity ◽  
Image Velocimetry

Polymer drag reduction is investigated using the Particle Image Velocimetry (PIV) technique in fully developed turbulent flow through a horizontal flow loop with concentric annular geometry (inner to outer pipe radius ratio = 0.4). The polymer used was a commercially available partially hydrolyzed polyacrylamide (PHPA). The polymer concentration was varied from 0.07 to 0.12% V/V. The drag reduction is enhanced by increasing polymer concentration until the concentration reaches an optimum value. After that, the drag reduction is decreased with the increasing polymer concentration. Optimum concentration value of PHPA was found to be around 0.1% V/V. Experiments were conducted at solvent Reynolds numbers of 38700, 46700 and 56400. The percent drag reduction was found to be increasing with the increasing Reynolds number. The study was also focused on analyzing the mean flow and turbulence statistics for fully-turbulent flow using the velocity measurements acquired by PIV. Axial mean velocity profile was found to be following the universal wall law close to the wall (i.e., y+ <10), but it deviated from log law results with an increased slope in the logarithmic zone (i.e., y+ >30). In all cases of polymer application, the viscous sublayer (i.e., y+ <10) thickness was found to be higher than that of the water flow. Reynolds shear stress in the core flow region was found to be decreasing with the increase in polymer concentration.

Different Modes of Gas Entrainment Through Bottom Discharge Branch by Using Three Dimensional Particle Image Velocimetry System

2007 ◽  
Author(s):  
Wael Fairouz Saleh ◽  
Ibrahim Galal Hassan
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Structure ◽  
Particle Image ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Particle Image Velocimetry System ◽  
Three Dimension ◽  
Two Phase ◽  
Mean Velocity ◽  
Image Velocimetry

The discharge of two-phase flow from a stratified region through single or multiple branches is an important process in many industrial applications including the pumping of fluid from storage tanks, shell-and-tube heat exchangers, and the fluid flow through small breaks in cooling channels of nuclear reactors during loss-of-coolant accidents (LOCA). Knowledge of the flow phenomena involved along with the quality and mass flow rate of the discharging stream(s) is necessary to adequately predict the different phenomena associated with the process. Particle Image Velocimetry (PIV) in three dimension was used to provide detailed measurements of the flow patterns involving distributions of mean velocity, vorticity field, and flow structure. The experimental investigation was carried out to simulate two phase discharge from a stratified region through branches located on a semi-circular wall configuration during LOCA scenarios. The semi-circular test section is in close dimensional resemblance with that of a CANDU header-feeder system, with branches mounted at orientation angles of zero, 45 and 90 degrees from the horizontal. The experimental data for the phase development (mean velocity, flow structure, etc.) was done during single discharge through the bottom branch from an air/water stratified region over a three selected Froude numbers. These measurements were used to describe the effect of outlet flow conditions on phase redistribution in headers and understand the entrainment phenomena.

Particle image velocimetry investigation of a turbulent boundary layer manipulated by spanwise wall oscillations

2002 ◽  
Vol 467 ◽  
pp. 41-56 ◽  
Author(s):  
GAETANO MARIA DI CICCA ◽  
GAETANO IUSO ◽  
PIER GIORGIO SPAZZINI ◽  
MICHELE ONORATO
Keyword(s):  
Boundary Layer ◽  
Particle Image Velocimetry ◽  
Turbulent Boundary Layer ◽  
Particle Image ◽  
Oscillation Amplitude ◽  
Research Programme ◽  
Oscillation Period ◽  
Wall Turbulence ◽  
Image Velocimetry ◽  
Near Wall

Particle image velocimetry has been applied to the study of a canonical turbulent boundary layer and to a turbulent boundary layer forced by transversal wall oscillations. This work is part of the research programme at the Politecnico di Torino aerodynamic laboratory with the objective of investigating the response of near-wall turbulence to external perturbations. Results are presented for the optimum oscillation period of 100 viscous time units and for an oscillation amplitude of 320 viscous units. As expected, turbulent velocity fluctuations are considerably reduced by the wall oscillations. Particle image velocimetry has allowed comparisons between the canonical and forced flows in an attempt to find the physical mechanisms by which the wall oscillation influences the near-wall organized motions.

scholarly journals Development of the optical electronic setup for carrying out measurements by multicolor Particle Image Velocimetry

2021 ◽  
Vol 2127 (1) ◽  
pp. 012018
Author(s):  
S S Usmanova ◽  
N M Skornyakova ◽  
Yu S Belov ◽  
M V Sapronov ◽  
A V Kuchmenko ◽  
...  
Keyword(s):  
Experimental Data ◽  
Particle Image Velocimetry ◽  
Computer Model ◽  
Vortex Structure ◽  
Test Object ◽  
3D Model ◽  
Particle Image ◽  
Velocity Fields ◽  
Laboratory Sample ◽  
Image Velocimetry

Abstract The paper is devoted to development of the optical electronic setup for carrying out measurements by multicolor particle image velocimetry. The main advantage of this method is the ability to visualize vector velocity fields in several planes simultaneously. As a result a 3D model of a setup was developed, a laboratory sample was assembled and series of testing experiments were performed. As a test object, vortex structure formed by a chemical stirrer in a cuvette with liquid has been considered. The experimental data were compared with the computer model developed in SolidWorks and FlowVision software.

POD Investigation of Near-Wall Turbulent Structures

2002 ◽  
Author(s):  
Gaetano Maria Di Cicca ◽  
Angelo Iollo ◽  
Pier Giorgio Spazzini ◽  
Gaetano Iuso ◽  
Michele Onorato
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Particle Image ◽  
Digital Particle Image Velocimetry ◽  
Orthogonal Decomposition ◽  
Wall Region ◽  
Turbulent Structures ◽  
Image Velocimetry ◽  
Proper Orthogonal ◽  
Near Wall

Experimental data of a turbulent boundary layer developing over a flat plate, obtained by Digital Particle Image Velocimetry (DPIV) technique, are analyzed making use of proper orthogonal decomposition (POD). Different POD definitions have been used in order to check their ability in educing the various structures dominating the near wall region. Results show a specific sensitivity depending on the POD definition adopted.

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