Mechanics of milk droplets in a shear flow

 

In this project, you will perform an experimental study of the dynamic deformation of milk droplets in a shear flow. This work is a part of a larger effort to better understand and optimize milk transport without degrading its quality.

Background

Deformation of vesicles by flow is a fluid mechanics problem with relevance for many applications, for instance: blood flow, transport of food products and oil/water separation. All these flows are characterized as carrier fluids that contain relatively large, deformable objects (i.e. red blood cells, milk fat globules, oil droplets in the aforementioned applications). From a physical and mathematical point of view, modeling the deformation and, ultimately, break-up of these vesicles is an immense challenge; this is in part due to the wide range of scales that are involved and the complex topology changes that can occur. An important asset would be a good experimental data set to validate numerical simulation tools. Better knowledge, e.g. maximum allowable shear rates, will also lead to better design of food product transport, e.g. during (automated) milking.

Project description

In this project, the student will

- perform a (very brief) literature study to establish correct dimensionless parameters and relevant questions
- adapt an existing microfluidic facility to study flow and deformation of vesicles at very high magnification (e.g. milk globules are in the range of 1-10 micrometer)
- find a suitable suspension for doing experiments (e.g. dilute milk fat globules);
- develop a protocol for performing experiments, study possibility of following vesicles using a translation stage
- develop and validate image processing software (Matlab) to determine vesicle shape
- characterize geometry variation as a function of shear rate (based on known Poiseuille flow profile)
- determine the threshold for "lysis" or destruction of the vesicles;
maximum shear rates (and duration)?

Depending on the progress of the project, the project can be extended to:

- find alternative method (imaging? fluorescence?) to determine vesicle properties