PhD Defence by Mikkel Paltorp Schmitt

Supervisors:

• Principal supervisor: Associate Professor, Vicente Cutanda Henriquez, DTU Electro, Denmark.
• Co-supervisor: Associate Professor, Niels Aage, DTU Construct, Denmark.

Assessment committee:

• Professor MSO Frieder Lucklum, DTU Electro, Denmark (chair).
• Associate Professor Luis Manuel Cortesão Godinho, Department of Civil Engineering of the University of Coimbra, Portugal
• Associate Professor Daan Huybrechs, KU Leuven, Belgium

Master of the ceremony:

• Associate Professor, Finn T. Agerkvist, DTU Electro, Denmark.

Abstract:
Acoustical simulations are important in the development of many modern human centered devices such as cellphones, hearing aids, and wearable microphones. However, as opposed to e.g. room acoustical simulations, the simulations of small devices must consider the loss of acoustical energy due to frictional forces the surface. Unfortunately, adding the extra complexity to the physical model results in significant increase in the overall computational efforts of the simulation.

In this thesis we look at a specific simulation technique called the boundary element method. This technique had two issues when including the loss of acoustical energy into the simulations. The findings in this thesis shows that it is possible to bypass these issues using two approaches: The first approach combines two ideas from acoustics while the second approach is based on a reformulation of the discrete equations making it possible to apply known techniques for approximating acoustical boundary element simulations.

The results of the first approach shows that it is possible to decrease the simulation time from days to hours using the same computational resources. The second approach shows that it is possible to solve problems on the hardware available on modern computers that used to require a large server.