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== '''Fall 2024''' ==
== '''Spring 2025''' ==
{| class="wikitable"
{| cellpadding="8"
|+
! align="left" |Date
!Date
! align="left" |Speaker
!Speaker
! align="left" |Title
!Title
! align="left" |Host(s)
!Host(s)
|-
|-
|Sep 13
|Jan 31
|[https://people.math.wisc.edu/~nchen29/ Nan Chen] (UW)
|[https://people.math.wisc.edu/~tgchandler/ Thomas Chandler] (UW)
|Uncertainty Quantification (UQ) for Beginners
|[[#Chandler|''Fluid–structure interactions in active complex fluids'']]
|
|-
|Feb 7
|[https://www.colorado.edu/aps/adrian-fraser Adrian Fraser] (Colorado)
|[[#Fraser|''Destabilization of transverse waves by periodic shear flows'']]
|Spagnolie
|Spagnolie
|-
|-
|Sep 20
|Feb 14
|[https://knewhall.web.unc.edu Katie Newhall] (UNC Chapel Hill)
|TBA
|
|
|
|Rycroft
|-
|-
|Sep 27
|Feb 21
|[https://ptg.ukzn.ac.za Indresan Govender] (Mintek / Univ. of KwaZulu-Natal, South Africa)
|TBA
|
|
|Rycroft
|-
|Oct 4*
|[https://sse.tulane.edu/math/people/hongfei-chen Hongfei Chen] (Tulane)
|
|
|Jean-Luc
|-
|-
|Oct 11 '''Colloquium in B239 at 4:00pm'''
|Feb 28
|[https://people.math.ethz.ch/~imikaela/ Mikaela Iacobelli] (ETH/IAS)
|[https://nmboffi.github.io/ Nick Boffi] (CMU)
|[[# TBA| TBA ]]
|[[#Boffi|TBA]]
|Li
|Li
|-
|-
|Oct 18 '''Colloquium in B239 at 4:00pm'''
|Mar 7
|[https://galton.uchicago.edu/~guillaumebal/ Guillaume Bal] (U Chicago)
|[https://sites.lsa.umich.edu/shankar-lab/ Suraj Shankar] (Michigan)
|[[# TBA| TBA ]]
|[[#Shankar|TBA]]
| Li, Stechmann
|Spagnolie
|-
|-
|Oct 25
|Mar 14
|[https://www.cs.cornell.edu/~damle/ Anil Damle] (Cornell)
|[https://lu.seas.harvard.edu/ Yue Lu] (Harvard) '''[Colloquium]'''
|
|[[#Lu|TBA]]
|Li
|Li
|-
|-
| Nov 1
|Mar 21
|[https://research-hub.nrel.gov/en/persons/michael-sprague Michael Sprague] (NREL)
|[https://people.llnl.gov/vogman1 Genia Vogman] (LLNL)
|[[# TBA| TBA ]]
|[[#Vogman|TBA]]
|Spagnolie
|Li
|-
|-
| Nov 8
|Mar 28
|[https://personal.math.ubc.ca/~holmescerfon/ Miranda Holmes-Cerfon] (UBC)
|''Spring Break''
|
|
|
|Stechmann
|-
|-
| Nov 15*
|Apr 4
| Yue Sun (UW–Madison)
|TBA
|
|
|
| Rycroft
|-
|-
| Nov 22
|Apr 11
|[https://ibd.uchicago.edu/joinus/yenfellowship/ Ondrej Maxian] (U Chicago)
|[https://meche.mit.edu/people/faculty/pierrel@mit.edu Pierre Lermusiaux] (MIT)
|[[# TBA| TBA ]]
|[[#Lermusiaux|TBA]]
|Ohm & Spagnolie
|Chen
|-
|-
| Nov 29*
|Apr 18
|''Thanksgiving''
|[https://www.math.uci.edu/~jxin/ Jack Xin] (UC Irvine) '''[Colloquium]'''
|
|[[#Xin|TBA]]
|
|
|-
|-
| Dec 6
|Apr 25
|[https://www.simonsfoundation.org/people/ido-lavi/ Ido Lavi] (Flatiron)
|[https://www-users.cse.umn.edu/~bcockbur/ Bernardo Cockburn] (Minnesota)
|[[# TBA| TBA  ]]
|[[#Cockburn|''Transforming stabilization into spaces'']]
|Spagnolie
| Stechmann, Fabien
|-
|-
|
|May 2
|[https://sylviaherbert.com/ Sylvia Herbert] (UCSD)
|[[#Herbert|TBA]]
|Chen
|}
|}


Dates marked with an asterisk correspond to [https://uwbadgers.com/sports/football/schedule home football games of the UW–Madison Badgers]. On these dates it can be difficult to get a hotel room close to campus at short notice.
==Abstracts==
 
<div id="Chandler">
====Thomas G. J. Chandler (UW)====
Title: Fluid-structure interactions in active complex fluids
 
Fluid anisotropy is central to many biological systems, from rod-like bacteria that self-assemble into dense swarms that function as fluids, to the cell cytoskeleton where the active alignment of stiff biofilaments is crucial to cell division. Nematic liquid crystals provide a powerful model for studying these complex environments. However, large immersed bodies elastically frustrate these fluids, leading to intricate interactions. This frustration can be alleviated through body deformations, at the cost of introducing internal stresses. Additionally, active stresses, arising from particle motility or molecular activity, disrupt nematic order by driving flows. In this presentation, I will demonstrate how complex variables enable analytical solutions to a broad range of problems, offering key insights into the roles of body geometry, anchoring conditions, interaction dynamics, activity-induced flows, and body deformations in many biological settings.


== Abstracts ==
<div id="Fraser">
====Nan Chen (UW–Madison)====
====Adrian Fraser (Colorado)====
Title: Taming Uncertainty in a Complex World: The Rise of Uncertainty Quantification -- A Tutorial for Beginners
Title: Destabilization of transverse waves by periodic shear flows


I will provide a tutorial about uncertainty quantification (UQ) for those who have no background but are interested in learning more about this area. The talk will exploit many elementary examples, which are understandable to graduate students and senior undergraduates, to present the ideas of UQ. Topics include characterizing uncertainties using information theory, UQ in linear and nonlinear dynamical systems, UQ via data assimilation, the role of uncertainty in diagnostics, and UQ in advancing efficient modeling. The surprisingly simple examples in each topic explain why and how UQ is essential. Both Matlab and Python codes have been made available for these simple examples.
Periodic shear flows have the peculiar property that they are unstable to large-scale, transverse perturbations, and that this instability proceeds via a negative-eddy-viscosity mechanism (Dubrulle & Frisch, 1991). In this talk, I will show an example where this property causes transverse waves to become linearly unstable: a sinusoidal shear flow in the presence of a uniform, streamwise magnetic field in the framework of incompressible MHD. This flow is unstable to a KH-like instability for sufficiently weak magnetic fields, and uniform magnetic fields permit transverse waves known as Alfvén waves. Under the right conditions, these Alfvén waves become unstable, presenting a separate branch of instability that persists for arbitrarily strong magnetic fields which otherwise suppress the KH-like instability. After characterizing these waves with the help of a simple asymptotic expansion, I will show that they drive soliton-like waves in nonlinear simulations. With time permitting, I will discuss other fluid systems where similar dynamics are or may be found, including stratified flows and plasma drift waves.
== Future semesters ==


*[[Applied/ACMS/Fall2024|Fall 2024]]
<div id="Cockburn">
====Bernardo Cockburn (Minnesota)====
Title: Transforming stabilization into spaces


*[[Applied/ACMS/Spring2025|Spring 2025]]
In the framework of finite element methods for ordinary differential equations, we consider the continuous Galerkin method (introduced in 72) and the discontinuous Galerkin method (introduced in 73/74). We uncover the fact that both methods discretize the time derivative in exactly the same form, and discuss a few of its consequences. We end by briefly describing our ongoing work on the extension of this result to some Galerkin methods for partial differential equations.


== Archived semesters ==
== Archived semesters ==


*[[Applied/ACMS/Fall2024|Fall 2024]]
*[[Applied/ACMS/Spring2024|Spring 2024]]
*[[Applied/ACMS/Spring2024|Spring 2024]]
*[[Applied/ACMS/Fall2023|Fall 2023]]
*[[Applied/ACMS/Fall2023|Fall 2023]]

Latest revision as of 22:02, 25 January 2025


Applied and Computational Mathematics Seminar


Spring 2025

Date Speaker Title Host(s)
Jan 31 Thomas Chandler (UW) Fluid–structure interactions in active complex fluids
Feb 7 Adrian Fraser (Colorado) Destabilization of transverse waves by periodic shear flows Spagnolie
Feb 14 TBA
Feb 21 TBA
Feb 28 Nick Boffi (CMU) TBA Li
Mar 7 Suraj Shankar (Michigan) TBA Spagnolie
Mar 14 Yue Lu (Harvard) [Colloquium] TBA Li
Mar 21 Genia Vogman (LLNL) TBA Li
Mar 28 Spring Break
Apr 4 TBA
Apr 11 Pierre Lermusiaux (MIT) TBA Chen
Apr 18 Jack Xin (UC Irvine) [Colloquium] TBA
Apr 25 Bernardo Cockburn (Minnesota) Transforming stabilization into spaces Stechmann, Fabien
May 2 Sylvia Herbert (UCSD) TBA Chen

Abstracts

Thomas G. J. Chandler (UW)

Title: Fluid-structure interactions in active complex fluids

Fluid anisotropy is central to many biological systems, from rod-like bacteria that self-assemble into dense swarms that function as fluids, to the cell cytoskeleton where the active alignment of stiff biofilaments is crucial to cell division. Nematic liquid crystals provide a powerful model for studying these complex environments. However, large immersed bodies elastically frustrate these fluids, leading to intricate interactions. This frustration can be alleviated through body deformations, at the cost of introducing internal stresses. Additionally, active stresses, arising from particle motility or molecular activity, disrupt nematic order by driving flows. In this presentation, I will demonstrate how complex variables enable analytical solutions to a broad range of problems, offering key insights into the roles of body geometry, anchoring conditions, interaction dynamics, activity-induced flows, and body deformations in many biological settings.

Adrian Fraser (Colorado)

Title: Destabilization of transverse waves by periodic shear flows

Periodic shear flows have the peculiar property that they are unstable to large-scale, transverse perturbations, and that this instability proceeds via a negative-eddy-viscosity mechanism (Dubrulle & Frisch, 1991). In this talk, I will show an example where this property causes transverse waves to become linearly unstable: a sinusoidal shear flow in the presence of a uniform, streamwise magnetic field in the framework of incompressible MHD. This flow is unstable to a KH-like instability for sufficiently weak magnetic fields, and uniform magnetic fields permit transverse waves known as Alfvén waves. Under the right conditions, these Alfvén waves become unstable, presenting a separate branch of instability that persists for arbitrarily strong magnetic fields which otherwise suppress the KH-like instability. After characterizing these waves with the help of a simple asymptotic expansion, I will show that they drive soliton-like waves in nonlinear simulations. With time permitting, I will discuss other fluid systems where similar dynamics are or may be found, including stratified flows and plasma drift waves.

Bernardo Cockburn (Minnesota)

Title: Transforming stabilization into spaces

In the framework of finite element methods for ordinary differential equations, we consider the continuous Galerkin method (introduced in 72) and the discontinuous Galerkin method (introduced in 73/74). We uncover the fact that both methods discretize the time derivative in exactly the same form, and discuss a few of its consequences. We end by briefly describing our ongoing work on the extension of this result to some Galerkin methods for partial differential equations.

Archived semesters


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