Flow of Quasi-2D Emulsion Droplets Through Small Openings Open Access

Hofert, Anisa (Spring 2020)

Permanent URL: https://etd.library.emory.edu/concern/etds/dv13zv22p?locale=en


We examine how various parameters affect the flow rate of quasi-2D soft particles moving through tight openings. To observe this, we create thin hopper-shaped chambers which have a small exit for the particles to flow through. We fill the chambers with monodisperse oil-in-water emulsions with a soap surfactant. We use microscopy to observe the oil droplets moving through the chamber, looking at deformation, particle flow, and outflow rate. We find that the exit size of the chamber is more important in determining the flow rate of the droplets than the number of droplets in the chamber. This means that the exit flux of the droplets is constant. There is a linear relationship between exit flux of the droplets and opening size. The flux goes to 0 when the ratio of the width of the opening and the diameter of the droplets (w/d) is less than 0.49 when extrapolated. The position of maximum deformation is also dependent on the w/d, with larger w/d having more deformation before the opening than at the opening.  

Table of Contents

1 Background                                                                                                 pg. 1

1.1 Motivation                                                                                                pg. 1

1.2 Particle Flow                                                                                            pg. 1

1.3 Beverloo Laws                                                                                         pg. 2

1.4 Soft Particle Flow                                                                                   pg. 3

1.5 Emulsions                                                                                                pg. 4

1.6 The Experiment                                                                                       pg. 5

2 Methods                                                                                                        pg. 6

           2.1 Microfluidic Device and Creating Emulsions                         pg. 6

                       2.1.1 Creating Emulsions                                                      pg. 6

                      2.1.2 Emulsion Coalescence and Size                                  pg. 8

           2.2 Chamber Development                                                               pg. 8

                       2.2.1 Creating Chambers                                                       pg. 8

                       2.2.2 Chamber considerations and testing                        pg. 9

                          Material Development                                  pg. 9

                          Shape Development                                       pg. 10

           2.3 Loading Chambers                                                                        pg. 11

           2.4 Microscopy                                                                                     pg. 13

           2.5 Particle Tracking                                                                           pg. 13

3 Results and Analysis                                                                                   pg. 14

           3.1 Video Observations and Clogging                                             pg. 14

           3.2 Deformation                                                                                   pg. 16

           3.3 Individual Droplet Motion                                                          pg. 19

           3.4 Droplet Flux                                                                                    pg. 21

4 Conclusion                                                                                                    pg. 23

5. Future Work                                                                                                 pg. 24

5.1 Changing Surface Tension/ Energy                                                       pg. 24

5.2 Changing Upward Force                                                                          pg. 25

5.3 Conclusion                                                                                               pg. 26

6 References                                                                                                     pg. 27

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