scholarly journals The Verification of Hybrid Image Deformation algorithm for PIV

2016 ◽  
Vol 14 (1) ◽  
pp. 48-52
Author(s):  
Jan Novotný ◽  
Ludmila Nováková
Keyword(s):  
Particle Image ◽  
Iterative Scheme ◽  
Peak Position ◽  
Relative Deformation ◽  
Accurate Calculation ◽  
Image Deformation ◽  
Advantages And Disadvantages ◽  
Image Velocimetry ◽  
Particle Image Velocimetry Method ◽  
Signal Peak

Abstract The aim of this paper was to test a newly designed algorithm for more accurate calculation of the image displacement of seeding particles when taking measurement using the Particle Image Velocimetry method. The proposed algorithm is based on modification of a classical iterative approach using a three-point subpixel interpolation and method using relative deformation of individual areas for accurate detection of signal peak position. The first part briefly describes the tested algorithm together with the results of the performed synthetic tests. The other part describes the measurement setup and the overall layout of the experiment. Subsequently, a comparison of results of the classical iterative scheme and our designed algorithm is carried out. The conclusion discusses the benefits of the tested algorithm, its advantages and disadvantages.

Out-of-Plane Motion Effects in Microscopic Particle Image Velocimetry

2003 ◽  
Vol 125 (5) ◽  
pp. 895-901 ◽  
Author(s):  
Michael G. Olsen ◽  
Chris J. Bourdon
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Laser Sheet ◽  
Plane Motion ◽  
Entire Volume ◽  
Measurement Volume ◽  
Microscopic Particle ◽  
Image Velocimetry ◽  
Out Of Plane ◽  
Signal Peak

In microscopic particle image velocimetry (microPIV) experiments, the entire volume of a flowfield is illuminated, resulting in all of the particles in the field of view contributing to the image. Unlike in light-sheet PIV, where the depth of the measurement volume is simply the thickness of the laser sheet, in microPIV, the measurement volume depth is a function of the image forming optics of the microscope. In a flowfield with out-of-plane motion, the measurement volume (called the depth of correlation) is also a function of the magnitude of the out-of-plane motion within the measurement volume. Equations are presented describing the depth of correlation and its dependence on out-of-plane motion. The consequences of this dependence and suggestions for limiting its significance are also presented. Another result of the out-of-plane motion is that the height of the PIV signal peak in the correlation plane will decrease. Because the height of the noise peaks will not be affected by the out-of-plane motion, this could lead to erroneous velocity measurements. An equation is introduced that describes the effect of the out-of-plane motion on the signal peak height, and its implications are discussed. Finally, the derived analytical equations are compared to results calculated using synthetic PIV images, and the agreement between the two is seen to be excellent.

A Method of Measuring Turbulent Flow Structures With Particle Image Velocimetry and Incorporating Into Boundary Conditions of Large Eddy Simulations

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Puxuan Li ◽  
Steve J. Eckels ◽  
Garrett W. Mann ◽  
Ning Zhang
Keyword(s):  
Particle Image Velocimetry ◽  
Large Eddy Simulation ◽  
Boundary Conditions ◽  
Particle Image ◽  
Advantages And Disadvantages ◽  
Eddy Simulation ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Large Eddy ◽  
Inlet Conditions

The setup of inlet conditions for a large eddy simulation (LES) is a complex and important problem. Normally, there are two methods to generate the inlet conditions for LES, i.e., synthesized turbulence methods and precursor simulation methods. This study presents a new method for determining inlet boundary conditions of LES using particle image velocimetry (PIV). LES shows sensitivity to inlet boundary conditions in the developing region, and this effect can even extend into the fully developed region of the flow. Two kinds of boundary conditions generated from PIV data, i.e., steady spatial distributed inlet (SSDI) and unsteady spatial distributed inlet (USDI), are studied. PIV provides valuable field measurement, but special care is needed to estimate turbulent kinetic energy and turbulent dissipation rate for SSDI. Correlation coefficients are used to analyze the autocorrelation of the PIV data. Different boundary conditions have different influences on LES, and their advantages and disadvantages for turbulence prediction and static pressure prediction are discussed in the paper. Two kinds of LES with different subgrid turbulence models are evaluated: namely dynamic Smagorinsky–Lilly model (Lilly model) and wall modeled large eddy simulation (WMLES model). The performances of these models for flow prediction in a square duct are presented. Furthermore, the LES results are compared with PIV measurement results and Reynolds-stress model (RSM) results at a downstream location for validation.

Design and implementation of a particle image velocimetry method for analysis of running gear–soil interaction

2013 ◽  
Vol 50 (5-6) ◽  
pp. 311-326 ◽  
Author(s):  
Carmine Senatore ◽  
Markus Wulfmeier ◽  
Ivan Vlahinić ◽  
Jose Andrade ◽  
Karl Iagnemma
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Design And Implementation ◽  
Image Velocimetry ◽  
Particle Image Velocimetry Method

An Experimental Review on Microbubble Generation to be Used in Echo-Particle Image Velocimetry Method to Determine the Pipe Flow Velocity

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Alinaghi Salari ◽  
M. B. Shafii ◽  
Shapour Shirani
Keyword(s):  
Particle Image Velocimetry ◽  
Contrast Agents ◽  
Particle Image ◽  
Low Cost ◽  
Ultrasound Contrast Agents ◽  
Surface Active Agents ◽  
Image Velocimetry ◽  
Particle Image Velocimetry Method ◽  
Microbubble Contrast Agents

Microbubbles are broadly used as ultrasound contrast agents. In this paper we use a low-cost flow focusing microchannel fabrication method for preparing microbubble contrast agents by using some surface active agents and a viscosity enhancing material to obtain appropriate microbubbles with desired lifetime and stability for any in vitro infusion for velocity measurement. All the five parameters that govern the bubble size extract and some efforts are done to achieve the smallest bubbles by adding suitable surfactant concentrations. By using these microbubbles for the echo-particle image velocimetry method, we experimentally determine the velocity field of steady state and pulsatile pipe flows.

Shallow and deep failure mechanisms during uplift and lateral dragging of buried pipes in sand

2020 ◽  
Vol 57 (10) ◽  
pp. 1472-1483
Author(s):  
Jinbiao Wu ◽  
George Kouretzis ◽  
Laxmi Suwal ◽  
Yousef Ansari ◽  
Scott W. Sloan
Keyword(s):  
Particle Image ◽  
Failure Mechanisms ◽  
Gradual Transition ◽  
Embedment Depth ◽  
Winkler Foundation ◽  
Buried Pipes ◽  
Ground Movements ◽  
Image Velocimetry ◽  
Particle Image Velocimetry Method ◽  
Series Of Experiments

This paper presents results of a series of experiments modelling uplift and lateral drag of a rigid pipe buried in dry sand. The main aim of these tests is to document the gradual transition from shallow to a deep sand failure mechanism as the pipe embedment depth increases, identify which parameters affect this transition, and determine experimentally the critical embedment depth, beyond which the normalized reaction acting on the pipe remains constant with increasing pipe embedment. Measurements of the reaction as a function of the relative sand–pipe movement and analysis of images captured during the tests with the particle image velocimetry method suggest that the critical embedment depth depends on sand density, but not on the direction of pipe movement. Outcomes of this study contribute to identifying the limits of applicability of simplified methods used to determine the peak reaction on pipes subjected to ground movements and the estimation of rational parameters for the analysis of deeply buried pipes with beam-on-nonlinear Winkler foundation models.

scholarly journals An experimental and numerical analysis of the fluid flow in a mechanically agitated vessel

2019 ◽  
Vol 128 ◽  
pp. 08002
Author(s):  
Marek Jaszczur ◽  
Anna Młynarczykowska ◽  
Luana Demurtas
Keyword(s):  
Fluid Flow ◽  
Particle Image ◽  
Numerical Study ◽  
Industrial Processes ◽  
Mixing Process ◽  
Agitated Vessel ◽  
Image Velocimetry ◽  
Particle Image Velocimetry Method ◽  
Widespread Phenomenon ◽  
Impeller Type

The mixing process is a widespread phenomenon, which plays an essential role among a large number of industrial processes. The effectiveness of mixing depends on the state of mixed phases, temperature, viscosity and density of liquids, mutual solubility of mixed fluids, type of stirrer, a what is the most critical - the shape of the impeller. In the present research, the objective is to analyse the process of the fluid flow in the mechanically agitated vessel with new impeller type. Velocity field values were determined using computer simulation and experimental particle image velocimetry method. The basis for the assessment of the intensity degree and efficiency of mixing was the analysis of velocity vectors distribution and power number. An experimental and numerical study was carried out for various stirred process parameters to determine optimal conditions for the mixing process.

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