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CBE Doctoral Dissertation Defense: “A Fractal Landscape Dynamics Approach to Understanding Particle Motion in Soft Jammed Materials” (Clary Rodríguez-Cruz)

March 22 at 2:00 PM - 3:30 PM

Abstract:

Soft jammed materials are disordered viscoelastic solids, composed of densely packed particles, that are commonly found both in the natural world and in a wide range of manufactured products. Their applications are widespread across various industries and technologies, including food, pharmaceuticals, agriculture and cosmetics. Understanding the fundamental physics and mathematics behind their highly complex particle motion and distinct response to external stress is essential for their improved design and stability, as well as the development of new materials with unique mechanical properties. Further, it is crucial for the development of theoretical models that better describe the complex interactions and dynamics of these materials. This thesis is centered around the observation that soft jammed materials exhibit fractal landscape dynamics, where the particles’ motion is not merely random but follows patterns influenced by the system’s underlying fractal energy landscape. Through experimental observations, theoretical models, and numerical simulations of ripening dense emulsions and foams, this work reveals two major findings. First, it demonstrates the numerical relationships between energy landscape geometry, microscopic particle dynamics, and macroscopic rheology through a novel high-dimensional approach. Second, it introduces a simplistic random walk model that generates fractal paths with specified dimensions, successfully reflecting the complex individual particle dynamics in a ripening foam after fitting to the data. This finding affirms the presence of fractal landscape dynamics as an explanation for behaviors such as non-Gaussian particle displacements, intermittent rearrangement events, and power-law rheology. Further exploration within this work extends the high-dimensional analysis framework to the dynamics of stock market prices, drawing an intriguing parallel between the motion of individual stocks and emulsion droplets. Lastly, the machine-learning metric of $\lq$softness’ is explored as a method to predict particle rearrangements in a ripening foam, showing that simply a particle’s number of neighbors achieves a surprisingly high prediction accuracy. This thesis not only enhances our understanding of soft jammed materials but also opens new avenues for applying fractal landscape dynamics across different materials and research fields.
Zoom Link: https://upenn.zoom.us/j/94077696014?pwd=Q3hLYXBkZGVhdlloZ3oyM2NReXZyZz09
Meeting ID: 940 7769 6014, Passcode: 794659

Clary Rodríguez-Cruz

CBE PhD Candidate

Thesis Advisor: John Crocker (CBE)

Committee Members: Robert A. Riggleman (CBE), Paulo E. Arratia (MEAM), Douglas Durian (Physics)

Details

Date:
March 22
Time:
2:00 PM - 3:30 PM
Event Categories:
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Event Tags:
Website:
https://upenn.zoom.us/j/94077696014?pwd=Q3hLYXBkZGVhdlloZ3oyM2NReXZyZz09

Organizer

Chemical and Biomolecular Engineering
Phone
215-898-8351
Email
chebiom@seas.upenn.edu
View Organizer Website

Venue

217 Towne – Forman Active Learning Classroom
220 South 33rd Street, Towne 217
Philadelphia, PA 19104 United States
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