On Water Waves with Angled Crests

Speaker: 

Sijue Wu

Institution: 

University of Michigan

Time: 

Friday, February 6, 2015 - 4:00pm to 5:00pm

Host: 

Location: 

RH 306

We consider the two-dimensional water wave problem in the case where the free interface of the fluid meets a vertical wall at a possibly non-trivial angle; our problem also covers interfaces with angled crests. We assume that the fluid is inviscid, incompressible, and irrotational, with no surface tension and with air density zero. We construct a low-regularity energy and prove a closed energy estimate for this problem, and we show that the two-dimensional water wave problem is solvable locally in time in this framework. Our work differs from earlier work in that, in our case, only a degenerate Taylor stability criterion holds, with $-\frac{\partial P}{\partial \bold{n}} \ge 0$, instead of the strong Taylor stability criterion $-\frac{\partial P}{\partial \bold{n}} \ge c > 0$. This work is partially joint with Rafe Kinsey.

Mathematical modelling and numerical simulation of fluid-structure interaction with application in hemodynamics

Speaker: 

Maria Lukacova

Institution: 

University of Mainz

Time: 

Monday, March 30, 2015 - 4:00pm to 5:00pm

Host: 

Location: 

RH306

Fluid-structure interaction problems appear in many areas. In the present lecture
we will concentrate on specific problems arising in hemodynamics. The aim will
be to study the resulting  nonlinear coupled system from analytical as well
as numerical point of view. We address theoretical questions of well-posedness and
present an efficient and robust numerical scheme in order to simulate blood flow in
compliant vessels. With respect to the numerical simulations we will in particular
discuss the questions of the added mass effect, stability and convergence order. We
will present results of numerical simulations and demonstrate the efficiency of new
kinematic splitting scheme.

Spectral geometry of toric Einstein Manifolds

Speaker: 

Tommy Murphy

Institution: 

Cal State Fullerton

Time: 

Tuesday, January 27, 2015 - 3:00pm

Location: 

RH 440R

The eigenvalues of the Laplacian encode fundamental
geometric information about a Riemannian metric. As an
example of their importance, I will discuss how they
arose in work of Cao, Hamilton and Illmanan, together
with joint work with Stuart Hall,  concerning stability
of Einstein manifolds and Ricci solitons. I will outline
progress on these problems for Einstein metrics with
large symmetry groups. We calculate bounds on the first
non-zero eigenvalue for certain Hermitian-Einstein four
manifolds. Similar ideas allow us estimate to the
spectral gap (the distance between the first and second
non-zero eigenvalues) for any toric Kaehler-Einstein manifold M in
terms of the polytope associated to M. I will finish by
discussing a numerical proof of the instability of the
Chen-LeBrun-Weber metric.

Energy-momentum inequalities in asymptotically anti-de Sitter spacetimes

Speaker: 

Naqing Xie

Institution: 

Fudan University and UC Irvine

Time: 

Tuesday, February 24, 2015 - 4:00pm to 5:00pm

Location: 

RH 306

We discuss certain inequalities for the Henneaux-Teitelboim total
energy-momentum for asymptotically anti-de Sitter initial data sets
which are asymptotic to arbitrary t-slice in anti-de Sitter spacetime. We
also give the relation between the determinant of the energy-momentum matrix
and the Casimir invariants. This is a joint work with Y. Wang and X. Zhang.

On the topology and index of minimal surfaces

Speaker: 

Davi Maximo

Institution: 

Stanford University

Time: 

Tuesday, February 3, 2015 - 4:00pm to 5:00pm

Location: 

RH 306

We show that for an immersed two-sided minimal surface in R^3,
there is a lower bound on the index depending on the genus and number of
ends. Using this, we show the nonexistence of an embedded minimal surface
in R^3 of index 2, as conjectured by Choe. Moreover, we show that the
index of an immersed two-sided minimal surface with embedded ends is
bounded from above and below by a linear function of the total curvature
of the surface. (This is joint work with Otis Chodosh)

Rigidity of local holomorphic isometries from a Kahler manifold to the product of of complex projective spaces

Speaker: 

Xiaojun Huang

Institution: 

Rutgers University

Time: 

Thursday, February 26, 2015 - 4:00pm to 5:00pm

Host: 

Location: 

RH306

We discuss the global property of a local holomorphic isometry into the product of projective spaces. We prove global extension and rigidity properties for such a map when the source is a Hermitian symmetric space  of compact type. Our work is along the lines of the previous work of Calabi, Clozel-Ullmo and Mok.
This is a joint work with Yuan Yuan from Syracuse University

Homology of curves and surfaces in closed hyperbolic 3-manifolds

Speaker: 

Yi Liu

Institution: 

Caltech

Time: 

Tuesday, November 25, 2014 - 4:00pm to 5:00pm

Location: 

RH 306

Closed quasi-Fuchsian subsurfaces of closed hyperbolic
3-manifolds constructed by J. Kahn and V. Markovic have played a crucial
role in the recent proof of the Virtual Haken Conjecture. In this talk, we
will investigate the techniques and construct homologically interesting
possibly bounded quasi-Fuchsian subsurfaces in closed hyperbolic
3-manifolds. We will focus on extending the geometric and topological
aspects from work of Kahn-Markovic, and will discuss further questions.
This is joint work with Vladimir Markovic.

Variational theory of minimal surfaces and applications

Speaker: 

Fernando Marques

Institution: 

Princeton University

Time: 

Thursday, January 22, 2015 - 4:00pm

Host: 

Location: 

Rowland Hall 306

Minimal surfaces are among the most natural objects in Differential Geometry, and are fundamental tools in the solution of several important problems in mathematics. In these two lectures we will discuss the variational theory of minimal surfaces  and describe recent applications to geometry and topology, as well as mention some future directions in the field. 
 

In particular we will discuss our joint work with Andre Neves on the min-max theory for the area functional. This includes the solution of the Willmore conjecture and the construction of infinitely many minimal hypersurfaces in manifolds with positive Ricci curvature. We will also discuss joint work with Agol and Neves on the Freedman-He-Wang conjecture about links. 

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