Abstracts for Invited Talks and Soundbites

82nd New England Complex Fluids Meeting
Brown University | Friday, March 13, 2020
Registration deadline: Wednesday, March 11, 2020

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Invited Talks

1. Bourouiba, Lydia


Life of bubbles at the interface
Bubbles are ubiquitous in industrial and environmental processes, indoors and outdoors, and have an important impact on a wide range of systems. They can be beneficial in mixing bulk water, they contribute significantly to the planetary-scale transfer of compounds from water bodies to the atmosphere and they are also sources of contamination. Upon reaching the air–water interface, bubbles are the source of myriads of droplets transporting the organisms, chemicals, or particles from the bulk in which they traveled to the air that we breathe. An understanding of this important source of droplets starts by understanding the formation, aging, and death of bubbles at the air–water interface. We start by focusing on the fundamental physics portion of the problem and how a large class of Marangoni-inducing effects fundamentally change the lifetime of bubbles. We discuss how physically and biologically induced Marangoni effects can sustain bubble lifetimes dramatically, with profound implications on dispersal of contaminants and life.

References/more resources: http://lbourouiba.mit.edu/research/projects/water-air-transfer-bubbles-interface


2. Mak, Michael

Yale University

Biophysical signals in the extracellular matrix: Interplay of cell dynamics and matrix properties
The extracellular matrix (ECM) in stromal microenvironments is typically comprised of a complex network of fibers. The ECM is a reservoir of biophysical and biochemical signals—including stiffness, alignment, tension, and ligand density—that can direct cell behavior and fate. Importantly, cells can induce the formation of these signals and create dynamic signaling profiles in the microenvironment. Many of these signals can be generated via the application of force, which induces strain-stiffening and strain-alignment of the local matrix. Additional signaling motifs can be achieved via the force-sensitive nature of the molecular bonds than interconnect fibers, which enables non-elastic remodeling. In our lab, we investigate, via computational and experimental methods, the regulators and underlying mechanisms that drive the emergence of these cell-generated signals in the microenvironment.

3. Olson, Sarah

Worcester Polytechnic Institute

Sperm navigation in complex environments
Microorganisms can swim in a variety of environments, interacting with chemicals and other proteins in the fluid. In this talk, we will highlight recent computational methods and results for swimming efficiency and hydrodynamic interactions of swimmers in different fluid environments. Sperm are modeled via a centerline representation where forces are solved for using elastic rod theory. The method of regularized Stokeslets is used to solve the fluid-structure interaction where emergent swimming speeds can be compared to asymptotic analysis. In the case of fluids with extra proteins or cells that may act as friction, swimming speeds may be enhanced and attraction may not occur. We will also highlight how parameter estimation techniques can be utilized to infer fluid and/or swimmer properties.

4. Zenit, Roberto

Brown University

Fluid mechanics of artistic painting
Painting is a fluid mechanical process. The action of covering a solid surface with a layer of a viscous fluid is one of the most common human activities; virtually all manmade surfaces are painted to provide protection against the environment or simply for decoration. This process, in an industrial context, has been vastly studied and it is well understood. In the case of artistic painting the purpose is different. Painters learn how to manipulate the nonuniform deposition of paint onto a surface, through lengthy empirical testing of the action and modifying the physical properties of the fluids, to create textures and patterns of aesthetic value. In this paper, an analysis of some notable painting techniques is presented from the point of view of fluid mechanics. In particular, we discuss the so-called "accidental painting" technique, originally devised by David A. Siqueiros, which is the result of a Rayleigh-Taylor instability. An analysis of several techniques used by Jackson Pollock is also presented, showing how he learned to carefully control the motion of viscous filaments to create his famous abstract compositions. We also briefly discuss how pattern and textures are produced in decalcomania and watercolor painting. These investigations indicate that it is possible to establish concrete scientific discussions among modern fluid mechanics, art, art history, and conservation.

Sound Bites

1. Berezney, John; Zvonimir Dogic, Seth Fraden

Brandeis University

Active cytoskeletal composite networks
We describe a new composite material composed of an active microtubule network driven by kinesin motors which interdigitates a second network of entangled actin filaments. We show such a material generates a wide variety of dynamic phenomena, including bulk contraction and bulk expansion, which we capture in a state diagram. Finally, we characterize the behavior in these states.
Keywords: active matter, actin, microtubules, kinesin

2. Bhaskar, Dhananjay; Ian Y. Wong

Brown University

Using Topological Data Analysis to Identify Patterns in Active Matter
I will outline a novel methodology to detect phase transitions and quantify pattern formation observed in soft-tissue cancer biology and in simulations of active matter. The proposed method, based on persistent homology, is model-agnostic, scale invariant, robust to noise and tolerant to changes in population size.
Keywords: pattern formation, active matter, soft tissues, topological data analysis

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© 2020 New England Complex Fluids Workshop
Supported by Harvard University's
Materials Research Science and Engineering Center