direkt zum Inhalt springen

direkt zum Hauptnavigationsmenü

Sie sind hier

TU Berlin

Page Content

Seminar "Thin Films", Winter Term 2011/12

Organisation
Coordinators:
Prof. Dr. Barbara Wagner, Dr. Kersten Schmidt
Dates:
Thu, 2-4 pm in room MA 645
Content:
Talks given by guests, members of staff and students on thin films and other topics of asymptotic analysis
Dates
Date
Time
Room
Speaker
Title
27.10.2011
2.15 pm
MA 645
Dr. Kersten Schmidt (TU Berlin)
High order transmission conditions for conductive thin sheets, Part I
03.11.2011
2.15 pm
MA 645
Dr. Kersten Schmidt (TU Berlin)
High order transmission conditions for conductive thin sheets, Part II
10.11.2011
2.15 pm
MA
645
Sebastian Jachalski (WIAS)
Stationary solutions for two-layer lubrication equation
17.11.2011
2.15 pm
MA
645
Dr. Anastasia Thöns-Zueva (TU Berlin)
High Order Asymptotic Expansion for Viscous Acoustic Equations Close to Rigid Walls (Abstract)
24.11.2011 
2.15 pm
MA 645
Dr. Dirk Peschka (WIAS)
Numerical algorithms and variational formulations for multiphase flows
01.12.2011
2.15 pm
MA 645
Dr. Maciek Korzec (TU Berlin)
Evolution of thin solid films and interfaces in photovoltaic devices
08.12.2011
2.15 pm
MA 645
Dr. Andreas Münch (University of Oxford)
A multiple scales approach to evaporation induced Marangoni convection
15.12.2011
2.15 pm
MA 645
Dr. Andreas Pflug (Fraunhofer IST, Braunschweig) 
Gasfluss- und Plasmasimulation für die
Dünnschichttechnik
12.01.2012
2.15 pm
MA 645
Dirk Klindworth (TU Berlin)
Computation of guided modes in photonic crystal wave guides
19.01.2012
Room and time changed
12.15 pm
MA 542
Dr. Bérangère Delourme (Caltech)
Asymptotic models for thin periodic layers in electromagnetism (Abstract)
26.01.2012
2.15 pm
MA 645
Dr. Georgy Kitavtsev (MPI Leizig)
Coarsening rates for liquid droplets in the presence of strong slippage
02.02.2012
2.15 pm
MA 645
Marion Dzwinik (TU Berlin) 
Surface diffusion dewetting of thin solid films
09.02.2012
Room and time changed
12.15 pm
MA 542
Matthias Liero (WIAS) 
Interface conditions in Reaction-diffusion equations
16.02.2012
2.15 pm
MA 645
tba
tba

Abstracts

Bérangère Delourme

Asymptotic models for thin periodic layers in electromagnetism
Donnerstag, 19. Januar 2011, 12:15 in MA 542

My talk is dedicated to the study of asymptotic models associated with electromagnetic waves scattering from a complex periodic ring, made of a dielectric ring containing two layers of wires winding around it. This is a joined work with P. Joly and H. Haddar. We are interested in situations where both the thickness of the ring and the distance between two consecutive wires are very small compared to the wavelength λ of the incident wave and the diameter of the ring. In these cases, numerical computations of the solution would become prohibitive as the small scale parameter (denoted by δ) goes to 0, since the mesh used needs to accurately follow the geometry of the heterogeneities. In order to overcome this difficulty, we shall derive approximate models where the periodic ring is replaced by e ffective transmission conditions on the mean interface Γ. The numerical discretization of approximate problems is expected to be much less expensive than the exact one, since the mesh no longer needs to be constrained by the small scale. From a technical point of view, these approximate models are derived from the asymptotic expansion of the solution with respect to the small parameter δ. Our method mixes matched asymptotic expansions and homogenization. We build the approximate transmission conditions from the truncated expansion.We pay particular attention to the justification of the asymptotic expansion and to the stabilization of the eff ective transmission conditions. Error estimates and numerical simulations are carried out to validate the accuracy of the models.

Keywords : matched asymptotic expansions, periodic homogenization, approximate transmission conditions, Maxwell's equations, Helmholtz equation.

Anastasia Thöns-Zueva

High Order Asymptotic Expansion for Viscous Acoustic Equations Close to Rigid Walls
Thursday, 17th November 2011, 14:15 in MA 645

In this study we are investigating the acoustic equations as a perturbation of the Navier-Stokes equations around a stagnant  uniform fluid and without heat flux. For gases the viscosities η and η' are very small and lead to viscosity boundary layers close to walls.  We will restrict our attention on those viscosity boundary layers and do not consider non-linear convection.

As there is a small factor η comes out in front of the curl curl operator in governing equations, the system is singularly perturbed, i.e.,  first, its formal limit η→ 0 does not provide a meaningful solution, and secondly, a boundary layer close to the wall ∂Ω appears. The choice of asymptotic expansion method seems to be the best adapted to this case.

In this approach we separate the solution in far field and correcting near field, where far field represents the area away the wall and exhibits no boundary layer, at the same time near field decays exponentially outside the zone of size O(√η) from the boundary.

To complete the solution, effective (impedance) boundary conditions are derived for the far field.

Zusatzinformationen / Extras

Quick Access:

Schnellnavigation zur Seite über Nummerneingabe

Auxiliary Functions