News & EventsDepartment Events
Events
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Feb4
EVENT DETAILS
lessTitle: Walking Droplets & Galloping Bubbles
Speaker: Pedro Saenz, University of North Carolina at Chapel Hill
Abstract: This talk explores two distinct problems in physics and engineering, blending experiments, simulations, and theory. The first part examines walking droplets, or "walkers," which self-propel across a vibrating fluid bath through a resonant interaction with their guiding wave field. These droplets exhibit behaviors typically associated with quantum particles, such as localized motion in disordered environments, which is akin to quantum Anderson localization. The study reveals that diffusion is suppressed when the guiding wave field interacts with random topographies, driven by a resonant coupling that creates an attractive wave potential, demonstrating how a classical particle can localize like a wave. The second part introduces a new mechanism where bubbles "gallop" along horizontal surfaces in a vertically vibrated fluid chamber, powered by interactions between their shape oscillations. These active bubbles can follow diverse trajectory patterns, including rectilinear, orbital, and run-and-tumble motions, which can be controlled by external forces. Through periodic deformations and inertial forces, these bubbles achieve self-propulsion without external direction. The study presents potential applications for galloping bubbles, including bubble manipulation, transport, sorting, navigation through complex fluid networks, and surface cleaning.
Zoom: https://northwestern.zoom.us/j/93833993196
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TIME Tuesday, February 4, 2025 at 11:15 AM - 12:15 PM
LOCATION M416, Technological Institute map it
CONTACT Ted Shaeffer ted.shaeffer@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)
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Feb25
EVENT DETAILS
lessTitle: Astrophysical Fluid Dynamics at Exascale
Speaker: Jim Stone, Institute for Advanced Study
Abstract: Most of the visible matter in the Universe is a plasma -- that is
a dilute gas of electrons, ions, and neutral particles -- interacting
with both magnetic and radiation fields. Studying the structure
and dynamics of astrophysical systems, from stars and planets, to
galaxies and the large-scale structure of the Universe itself,
usually requires numerical methods to solve the coupled equations
of compressible radiation magnetohydrodynamics (MHD). Robust
numerical algorithms for modeling astrophysical fluids, including
new methods for calculating radiation transport in relativistic
flows, will be discussed. Efficient implementation of these methods
on modern high-performance computing systems is crucial, and an
approach based on the Kokkos programming model that enables performance
portability will be described. Performance on a variety of
architectures of a new adaptive mesh refinement (AMR) astrophysical
MHD code will be given, including scaling on up to 65536 GPUs on
the OLCF Frontier exascale computer. Finally, a case study will
be presented that demonstrates some of the many new insights that
have come from applying computational methods to one particular problem:
how plasma accretes onto the black holes in the centers of galaxies.Zoom: https://northwestern.zoom.us/j/95581369835
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TIME Tuesday, February 25, 2025 at 11:15 AM - 12:15 PM
LOCATION M416, Technological Institute map it
CONTACT Ted Shaeffer ted.shaeffer@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)
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Mar4
EVENT DETAILS
lessTitle: A Wave Theory of Waves
Speaker: Mark Hoefer, University of Colorado Boulder
Abstract: Hydrodynamic theories describe long wave propagation in a continuum, such as a fluid where the microscopic constituents are interacting fluid particles. When the constituents are interacting waves rather than particles, we arrive at a macroscopic wave theory of waves called dispersive hydrodynamics. A canonical example is the dispersive shock wave or DSW, which consists of an unsteady (expanding) collection of nonlinear oscillations terminating with zero amplitude (harmonic limit) at one end and zero wavenumber (soliton limit) at the other. Scale separation leads to the mathematical framework of nonlinear wave modulation theory, originally developed by G. B. Whitham in 1965. This talk will present a variety of developments and results in dispersive hydrodynamics utilizing Whitham modulation theory, numerical simulations, and experiment.
Zoom: https://northwestern.zoom.us/j/98867883380
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To subscribe to the Applied Mathematics Colloquia List send a message to LISTSERV@LISTSERV.IT.NORTHWESTERN.EDU with the command:
add esam-seminar Youremail Firstname Lastname
TIME Tuesday, March 4, 2025 at 11:15 AM - 12:15 PM
LOCATION M416, Technological Institute map it
CONTACT Ted Shaeffer ted.shaeffer@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)
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Mar11
EVENT DETAILS
lessTitle: Active Particles in Inhomogeneous Environments
Speaker: Vaseem Shaik, Northwestern University
Abstract: Active particles are entities, either living (like microorganisms, birds, and humans) or non-living (like nanorobots), that convert stored energy into directed motion. A suspension of these particles is called active matter. They often navigate through inhomogeneous environments such as gradients in heat, light, nutrients, or fluid properties like viscosity and density, exhibiting directed motion known as taxis (e.g., chemotaxis, phototaxis, gravitaxis). This summary focuses on μm - mm-sized particles swimming in fluids with mechanical property gradients, like viscosity, elasticity, and density. It discusses phenomena like viscotaxis (response to viscosity gradients), behavior similar to light refraction in viscosity gradients (described by a Snell’s law), durotaxis (response to elasticity gradients), and densitaxis (response to density gradients), with implications for plankton migration. The study also covers particle-induced mixing and the influence of noise, exploring how these inhomogeneities can control active matter in confined environments.
Zoom: https://northwestern.zoom.us/j/96970714028
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TIME Tuesday, March 11, 2025 at 11:15 AM - 12:15 PM
LOCATION M416, Technological Institute map it
CONTACT Ted Shaeffer ted.shaeffer@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)
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Mar15
EVENT DETAILS
lessWinter Classes End
TIME Saturday, March 15, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar
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Mar17
EVENT DETAILS
lessWinter exams begin
TIME Monday, March 17, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar
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Mar22
EVENT DETAILS
lessSpring Break Begins
TIME Saturday, March 22, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar
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Mar31
EVENT DETAILS
lessSpring Break Ends
TIME Monday, March 31, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar