UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl)
UvA-DARE (Digital Academic Repository)
Drops and jets of complex fluids
Javadi, A.
Publication date
2013
Link to publication
Citation for published version (APA):
Javadi, A. (2013). Drops and jets of complex fluids.
General rights
It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons).
Disclaimer/Complaints regulations
If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible.
Contents
1 General Introduction 1
1.1 Drops . . . 1
1.1.1 Surface tension . . . 2
1.1.2 Wetting . . . 3
1.1.3 Dynamic of partial wetting . . . 4
1.2 Jets . . . 5
1.3 Contents . . . 6
2 Effect of Wetting Properties on Capillary Pumping in Microchan-nels 11 2.1 Introduction . . . 11
2.1.1 Microfluidics and its applications . . . 12
2.1.2 Micropumps . . . 12
2.2 A surface tension driven micropump . . . 13
2.3 3-phase flow . . . 14
2.3.1 2-drops system numerical analysis . . . 16
2.4 Backflow . . . 18
2.4.1 Backgrounds . . . 18
2.4.2 Experiments and results . . . 20
2.5 Electrowetting : bi-directional active pumping . . . 22
2.5.1 Theoretical backgrounds . . . 25
2.5.2 Experiments and setup . . . 28
2.6 Conclusion . . . 31 i
ii CONTENTS
3 Dynamics of Ferrofluid drops 33
3.1 Introduction . . . 33
3.2 Ferrofluids . . . 34
3.2.1 Stability requirements . . . 34
3.2.2 Some applications of ferrofluids . . . 36
3.3 Drop Characteristics . . . 38
3.4 Dynamics: Sliding Shaped drops on an inclined plane . . . 40
3.4.1 Discussion on the acting forces . . . 42
3.4.2 Extracting the perimeter . . . 45
3.4.3 Analyzing the data . . . 46
3.5 Conclusion and perspectives . . . 48
4 Delayed capillary breakup of falling viscous jets 51 4.1 Introduction . . . 51
4.2 History and backgrounds . . . 52
4.3 Rayleigh Instability . . . 54
4.4 Long wave-length approximation . . . 56
4.5 Experiments of the viscous falling jet . . . 58
4.6 Theoretical investigation . . . 59
4.6.1 Dimensional analysis . . . 59
4.6.2 WKB analysis . . . 65
4.6.3 High-viscosity limit . . . 67
4.7 conclusion . . . 70
5 The Non-Newtonian Hydraulic Jump 71 5.1 Introduction . . . 71
5.2 Newtonian hydraulic jump . . . 72
5.2.1 Inviscid jump . . . 72
5.2.2 Viscous Theory . . . 74
5.2.3 Surface tension . . . 76
5.3 Non-Newtonian hydraulic jumps . . . 77
5.4 Rheological properties . . . 80
5.5 Non-Newtonian experiments . . . 81
CONTENTS iii
6 Coiling of Yield Stress Fluids 87
6.1 Introduction . . . 87
6.1.1 Coiling of Newtonian fluids . . . 89
6.2 Coiling of elastic ropes . . . 93
6.2.1 Regimes of coiling . . . 96
6.3 Yield stress fluids . . . 98
6.4 Coiling of yield stress fluids . . . 98
6.4.1 Experimental procedure and observations . . . 99
6.4.2 Results and discussion . . . 101
6.5 Conclusion . . . 106 Bibliography 107 Summary 115 Samenvatting 117 List of publications 119 Acknowledgements 120
