FLOW VISUALIZATION AND IMAGE ANALYSIS

FLUID MECHANICS AND ITS APPLICATIONS

Volume 14

Series Editor: R. MOREAU MADYLAM Ecole Nationale Superieure d'Hydraulique de Grenoble Boite Postale 95 38402 Saint Martin d' Heres Cedex, France

Aims and Scope of the Series

The purpose of this series is to focus on subjects in which fluid mechanics plays a fundamental role.

As well as the more traditional applications of aeronautics, hydraulics, heat and mass transfer etc., books will be published dealing with topics which are currently in a state of rapid development, such as turbulence, suspensions and multiphase fluids, super and hypersonic flows and numerical modelling techniques.

It is a widely held view that it is the interdisciplinary subjects that will receive intense scientific attention, bringing them to the forefront of technological advance­ment. Fluids have the ability to transport matter and its properties as well as transmit force, therefore fluid mechanics is a subject that is particulary open to cross fertilisation with other sciences and disciplines of engineering. The subject of fluid mechanics will be highly relevant in domains such as chemical, metallurgical, biological and ecological engineering. This series is particularly open to such new multidisciplinary domains.

The median level of presentation is the first year graduate student. Some texts are monographs defining the current state of a field; others are accessible to final year undergraduates; but essentially the emphasis is on readability and clarity.

For a list oJ related mechanics titles, see Jinal pages.

Flow Visualization and Image Analysis

edited Ьу

F. Т. М. NIEUWSTADT Laboratory [or Aero and Hydromeclzanics, Technical University о[ Del[t, The Netllerlands

SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.

Library ofCongress Cata1oging-in-Publication Data

Flow visualization and image analys1s I ed1ted Ьу F.T.M. Nieuwstadt. р. ст. -- (Flu1d mechan1cs and its applications ; v. 14)

ISBN 978-94-010-5191-0 ISBN 978-94-011-2690-8 (eBook) DOI 10.1007/978-94-011-2690-8 1. Flow visualization. 2. Image processing. 3. Fluid mechanics­

-Data process;ng. 1. Nieuwstadt, F. Т. М. (Frans Т. М.), 1946-II. Ser1es. TA357.F544 1992 681' .2--dc20

ISBN 978-94-010-5191-0

Printed оп acid-free paper

АН Rights Reserved © 1993 Springer Science+Business Media Dordrecht

Origina11y published Ьу Кluwer Academic Publishers in 1993 Softcover reprint ofthe hardcover 1st edition 1993

92-32223

No рзrt of the materia1 protected Ьу this copyright notice тау Ье reproduced or utilized in апу form or Ьу апу means, e1ectronic or mechanica1, including photocopying, recording or Ьу anу information storage and retrieva1 system, without written permission from the copyright owner.

Table of Contents

Preface vii

R.D. Keane and R.I. Adrian Theory of cross-correlation analysis of PIV images

S.B. Dalziel Decay of rotating turbulence: Some particle tracking experiments 27

H. Stapountzis, J. Westerweel, J.M. Bessem, A Westendorp and F.T.M. Nieuwstadt Measurement of product concentration of two parallel reactive jets using digital image processing 55

H.A Siller, R.J. Perkins and G. Janke Image analysis of oil film interferometry - a method of measuring wall shear stress distributions 71

L. Lourenco Recent advances in LSV, PIV and PTV 81

P. Guibert, Q.C. Duan, M. Murat and J. Julien Development of particle image velocimetry: A new computation method with direc-tional resolution 101

A Chavez and F. Mayinger Algorithms for automatic measurements of size and velocity of spray droplets from holography reconstructions 117

J. Massons, Jna. Gavalda, J. Escoda, X. Ruiz and F. Diaz Characterization of Savonius rotor wake using image analysis processing techniques 143

V. Baier, W. Bechteler and S. Hartmann An application of image processing methods to determine the critical shear stress in sewer systems 159

M.P. Arroyo and C.A Greated A three dimensional particle image velocimetry system and its application to the measurement of acoustic streaming 167

e. Hugi and A. Mueller A camera for measuring density, size and velocity of rising air bubbles and water velocity in a bubble plume 189

D.R. McCluskey, e. Elgaard, W.I. Easson and e.A. Greated The application of PIV to turbulent two-phase flow 207

P.A. Quinn, D.I. Skyner, e. Gray, C.A Greated and W.J. Easson A critical analysis of the particle image velocimetry technique as applied to waves 227

J. Stefanini, G. Cognet, J.e. Vila, B. Merite and Y. Brenier A colored method for PIV technique 247

AK. Hind Digital PIV applied to flows around artificial heart valves: Analysis by autocorrelation 259

PREFACE Image analysis as measuring technique in flows

Progress in fluid mechanics depends heavily on the availability of good experimental data which can inspire new ideas and concepts but which are also necessary to check and validate theories and numerical calculations. The usual experimental probes, such as the pitot tube, the hot wire but also the more advanced laser-doppler equipment, can be characterized as point measurements, i.e. they only give us information in a single spatial point in the flow field. Although useful, such information is at the same time quite limited especially when flow phenomena are dominated by spatial structures. A primary example of the latter case is turbulent flow. One may even venture to say that these limitations of experimental tools have hampered the progress in this field.

With the advent of new recording and image analysis techniques new and promising eX'perimental methods in fluid flows have presented themselves ,vhich are able to obtain spatial information. In some aspects these techniques are almost old­fashioned because they use the well established methods of flow visualization. Howev~r, the progress lies in the fact that now we are able to obtain quantitative information from these visualizations by applying the methods of image analysis. Examples are the rather newly developed techniques such as particle tracking velocimetry (PTV), particle image velocimetry (PlV) and laser induced fluorescence (LIF).

Within the regular series of Euromech colloq uia a meeting was organized to discuss the rapid developments in this ne\v field of the application of image analysis techniques to flow measurements. The meeting was held at the Delft University of Technology from July 2 until July 5, 1991 under the title Euromech 279, Image Analysis as Measuring Technique in Flows.

At this colloquium invited lectures were given by experts in the field on various specific topics. In addition shorter presentations were given by the participants on their recent results. We feel that some of these presentations are interesting for a wider audience, because they offer up to date information on this rapidly developing new experimental field. Therefore, participants at the colloquium were invited to submit their presentations for publication.

All submissions were subjected to the usual reviewing procedure. As an outcome of this procedure four papers have been selected to be published in an issue of Applied Scientific Research. These papers are also thought to represent characteristic examples of various techniques. The other papers, which certainly contain interesting and new material on various aspects of image analysis, have been collected together. In this proceedings the four articles mentioned above have also been reprinted so that a rather complete overview is given of the present state of the art on the use of image analysis techniques in flow measurements.

vii

F.T.M. NIEUWSTADT

Editor

Fig.7. Representative steps of the image processing of a single pulsed holo­

gram of the RIl3 spray.

1) Original image, 2) smoothing and gradient extraction and 3) hi·

narization. The right picture column shows an enlargement Al of

the droplet zone of picture (1), its noise filtering and the final droplet

identification. (p. 134)

posilon downstream from grid/rum

.... ,.UoI\1 .. bo •• ,~ ru, _ ,~ ru. _ ,~

~ - ,." =- ~ ~- = =- ~ 0.01 - 0.G3

-om - om -0.03 - -om -0.06 - -{I.03 -{1m - -{I.06 ~ -~

-{Ill - -o.oIiI -{I.IS - -{I.U -o.~ - -0.13

.OM.., I(1 t..low -Ol~

Figure 6: Vorticity map of a the flow field shown in Figure 5. (p. ~ 16)

TRIPLETS PHOTOGRAPH

TRIPLETS PHOTOGRAPH

Ifg.7a (p . 256)

fig. Sa

(p. ~57)