Tailoring Wave Propagation by Computational Morphogenesis - Topology Optimization for Acoustic, Elastic and Electromagnetic Waves

18 Sep
Applied Mechanics Colloquia
Rasmus Christiansen, Denmark Technical University
Wednesday, September 18, 2019 - 4:00pm to 5:00pm
Pierce 209

Having the ability to control the propagation of waves through physical systems has numerous applications. For example; being able to ensure the rapid attenuation of vibrations in moving mechanical structures, such as components of cars, airplanes or windmills can reduce noise and prohibit catastrophic vibration induced failures; being able to enhance energy focusing and control wave interference enables the detection of weak physical phenomena; tailoring scattering and dispersion phenomena enables the filtering of signals. The list of applications is long and growing as new technologies emerge. While carefully engineered solutions to many such problems already exist, they are often sub-optimal, leaving design space for improvements. Analytical design rules developed from simplified models, parametric studies using advanced physical models and even human intuition, based on decades of experience, all have their limitations, making it nay impossible to explore and exploit the full design space for a given problem using such tools. Meanwhile, the exponential growth of computational power, the invention and improvement of numerical tools for accurately simulating wave phenomena along with the invention of efficient mathematical optimization methods over the last decades have enabled the development of powerful design tools with unprecedented capabilities. Density based topology optimization is one such tool having recently been proven capable of solving design problems with a billion design variables, translating to virtually unlimited design freedom. This talk will focus on recent research into the development and application of density based topology optimization to the design of structures and metamaterials achieving a high degree of control of various wave phenomena. This includes metamaterials with exotic properties and passive structures designed for wave propagation control. Initially a brief introduction to the method is provided, taking offset in a static mechanical engineering example, followed by examples of recent applications of the method across different areas of physics.

Speaker Bio: 

I hold a BSc in Physics and Nanotechnology (2011), an MSc in Computational Mathematics (2013) and a PhD-degree (2016) from the Department of Mechanical Engineering at the Technical University of Denmark (DTU). My PhD-fellowship was focussed on the development, application and experimental validation of topology optimization based methods for solving wave propagation based design problems in acoustics and optics.

I am currently working as a postdoctoral researcher at DTU, where I have been involved in several projects, among which are the SunTune project and the NATEC project. The SunTune project is centered at Aarhus University and concerns the design of passive solar cell components aimed at increasing their operating efficiency. This includes the design of metallic nanoparticles for localized electromagnetic field enhancement. The NATEC project is centered at the Department of Photonics at DTU and is focussed on the design of active and passive photonic structures for applications in optical data processing and terabit communication. 

Currently, I am visiting the Department of Mathematics at MIT as a short-term scholar, where I work with Professor Steven G. Johnson's group on Raman scattering problems and optical metasurfaces.


SunTune: Plasmonic particle design with photovoltaic applications.

NATEC: Active materials (quantum wells and quantum dots), designing photonic structures with applications in optical data processing and terabit communication.

Visiting MIT (Current): Designing Particles for enhanced Raman scattering. Designing optical meta surface

Other: Control and manipulation of acoustic wave propagation.

John Hutchinson
Nick Grall