Applied/ACMS: Difference between revisions

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|Jan 31
|Jan 31
|[https://people.math.wisc.edu/~tgchandler/ Thomas Chandler] (UW)
|[https://people.math.wisc.edu/~tgchandler/ Thomas Chandler] (UW)
|
|[[#Chandler|TBA]]
|
|
|-
|-
|Feb 7
|Feb 7
|Adrian Fraser
|[https://www.colorado.edu/aps/adrian-fraser Adrian Fraser] (Colorado)
|
|[[#Fraser|''Destabilization of transverse waves by periodic shear flows'']]
|Spagnolie
|Spagnolie
|-
|-
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|Feb 28
|Feb 28
|[https://nmboffi.github.io/ Nick Boffi] (CMU)
|[https://nmboffi.github.io/ Nick Boffi] (CMU)
|
|[[#Boffi|TBA]]
|Li
|Li
|-
|-
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|Mar 14
|Mar 14
|[https://lu.seas.harvard.edu/ Yue Lu] (Harvard) '''[Colloquium]'''
|[https://lu.seas.harvard.edu/ Yue Lu] (Harvard) '''[Colloquium]'''
|
|[[#Lu|TBA]]
|Li
|Li
|-
|-
|Mar 21
|Mar 21
|reserved
|[https://people.llnl.gov/vogman1 Genia Vogman] (LLNL)
|
|[[#Vogman|TBA]]
|
|Li
|-
|-
|Mar 28
|Mar 28
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|Apr 11
|Apr 11
|[https://meche.mit.edu/people/faculty/pierrel@mit.edu Pierre Lermusiaux] (MIT)
|[https://meche.mit.edu/people/faculty/pierrel@mit.edu Pierre Lermusiaux] (MIT)
|
|[[#Lermusiaux|TBA]]
|Chen
|Chen
|-
|-
|Apr 18
|Apr 18
|[https://www.math.uci.edu/~jxin/ Jack Xin] (UC Irvine) '''[Colloquium]'''
|[https://www.math.uci.edu/~jxin/ Jack Xin] (UC Irvine) '''[Colloquium]'''
|
|[[#Xin|TBA]]
|
|
|-
|-
|Apr 25
|Apr 25
|[https://www-users.cse.umn.edu/~bcockbur/ Bernardo Cockburn] (Minnesota)
|[https://www-users.cse.umn.edu/~bcockbur/ Bernardo Cockburn] (Minnesota)
|''Transforming stabilization into spaces''
|[[#Cockburn|''Transforming stabilization into spaces'']]
| Stechmann, Fabien
| Stechmann, Fabien
|-
|-
|May 2  
|May 2  
|[https://sylviaherbert.com/ Sylvia Herbert] (UCSD)
|[https://sylviaherbert.com/ Sylvia Herbert] (UCSD)
|
|[[#Herbert|TBA]]
|Chen  
|Chen  
|}
|}


==Abstracts==
==Abstracts==
<div id="Fraser">
====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)====
====Bernardo Cockburn (Minnesota)====
Title: Transforming stabilization into spaces
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.<div id="Bal"><div id="Portone"><div id="Damle"><div id="Sprague"><div id="Holmes-Cerfon"><div id="Sun"><div id="Maxian"><div id="Lavi">
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.
 
<div id="Bal"><div id="Portone"><div id="Damle"><div id="Sprague"><div id="Holmes-Cerfon"><div id="Sun"><div id="Maxian"><div id="Lavi">
 
== Archived semesters ==
== Archived semesters ==


Latest revision as of 21:41, 22 January 2025


Applied and Computational Mathematics Seminar


Spring 2025

Date Speaker Title Host(s)
Jan 31 Thomas Chandler (UW) TBA
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 TBA
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

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.

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