GAMM2025

Session

S12: Waves and Acoustics

S12

8 Apr 2025, 08:30

Lecture and Conference Centre

Conveners

S12: Waves and Acoustics: S12.01

• Anna Sygulska

S12: Waves and Acoustics: S12.02

• Michał Guminiak

S12: Waves and Acoustics: S12.03

• Michael Beitelschmidt

Description

Waves are a ubiquitous natural phenomenon and acoustics are, besides surface water waves, the most obvious representatives, familiar to anybody and quantitatively known to any student of mathematics, physics or a technical subject. To this corresponds a long mathematical tradition, continuing today in the accurate numerical computation of linear and nonlinear wave phenomena. Our session is devoted to the simulation and understanding of waves and wave interactions. The range of applications is thus very broad, while the focus is meant to be on the unifying physical phenomenon. In the past years we had numerous contributions from solid mechanics, porous media flow, turbulence and aeroacoustics, from crack detection to explosions.

283. Analysis of the formation of caustic by a concave reflector in a geometric and wave field

Andrzej Kulowski

08/04/2025, 08:30

The historical development of the concept of caustics and its applications in science and technology is shown, starting from the works of Leonardo da Vinci (LdV) to contemporary achievements in the field of radio astronomy.

Starting from LdV research in the field of light propagation, caustics present in his drawings on the topic of reflecting light by concave mirrors were analyzed. The...

284. Numerical Study on Enhanced Impedance Matching for Symmetric Lamb Waves in FML with Integrated Sensors

Max Rottmann

08/04/2025, 09:10

Fibre Metal Laminates (FML) constitute an advanced composite material class that combine the strength and ductility of metals with the lightweight and high-stiffness properties of fibre reinforced polymers, and thus become a promising material system for applications in aerospace, automotive engineering, and other engineering fields. Structural Health Monitoring (SHM) using Guided Ultrasonic...

285. Acoustic black holes in the Rayleigh-Lamb Theory

David Schoenebeck

08/04/2025, 09:30

Tapered edges in beams have been attracting attention in engineering science for their passive vibration damping properties [1]. Flexural waves propagating into a power-law-shaped beam edge slow down with decreasing beam thickness until the phase and group velocities are zero at the tip. Standing waves, often undesired in engineering, cannot form in a beam with a perfectly tapered edge due to...

286. Wave propagation in non uniform media by linear expansion of the refraction law

Alessandro Bassetti

08/04/2025, 09:50

The propagation of mechanical waves in an unbounded, non uniform medium can be described by using curvilinear coordinates centred at source position. The Frenet coordinate system, with origin on a point riding a wave, is used as basis for the curvilinear coordinates. In this way a principal coordinate stating the evolution of the wave field and running along a ray, orthogonally to the...

287. One-way wave equation

Oskar Bschorr

08/04/2025, 10:10

Kinematically, the elastic deflection in a solid can be traced back to 3 irreducible types of deformation {Dil, Rot, Dev}: The dilatation Dil is defined by the div-operator, the change in direction Rot by the rot-operator and the shape change Dev by the dev-operator. These deformations are automatically determined thanks to the mathematical well known identities rot grad = 0 and div rot =...

288. Acoustic Waves at Very Low Frequency: Propagation and Building Insulation

Costantino Carlo Mastino

08/04/2025, 16:30

Acoustic waves at very low frequencies (straddling infrasound and sound) are produced by various sources, including wind turbines. These waves, with frequencies even below 20 Hz, can propagate over long distances and easily penetrate buildings. Wind turbines generate infrasound primarily due to the movement of the blades and mechanical components. The acoustic insulation of building facades is...

289. Stretch ceilings in church acoustics design

Anna Sygulska

08/04/2025, 16:50

Issues of church design are inseparably linked with the sound function. In the contemporary Poznań churches studied by the author, built between 1970 and 2000, there are no deliberate solutions to influence the interior acoustics. Suitable acoustic conditions were obtained accidentally. The last two decades have seen a new trend in church interior design. Targeted measures are being introduced...

290. Can one hear the shape of a crack in a drum? - An analytical and data-based approach

Philipp Zilk

08/04/2025, 17:10

The eigenfrequencies of a vibrating membrane generally depend on its shape. The associated inverse problem was made famous by the work of Kac and has been widely discussed in the literature. We consider this problem in the context of cracks. Is it possible to identify a crack in a membrane if its eigenfrequencies are known?

To answer this question, we first present an analytical approach...

291. Time-Domain Simulation of Brass Instruments with the Method of Characteristics

Daniel Aurich

08/04/2025, 17:30

Sound propagation in brass instruments is dominated by spatial and non-linear effects arising from high sound pressure levels. To simplify analysis, one-dimensional linear frequency-domain models, such as the Transfer-Matrix Method, are commonly used to calculate the input impedance of brass instruments. These models neglect non-linear effects and typically assume planar or spherical wave...

292. Towards the efficient simulation of large-scale soil-structure interaction problems using the scaled boundary finite element method

Tobias Kuhn

09/04/2025, 08:30

Modeling wave propagation in soil or soil-structure domains using conventional finite element methods necessitates the simulation of extensive spatial domains to avoid reflections at artificial boundaries and to ensure the accuracy of absorbing boundary conditions. Especially for three-dimensional problems, the computational costs associated with this approach increases significantly, making...

293. Time Domain Boundary Element Methods for the Neumann Problem: a Reduced Formulation for Practical Applications

Simon Schneider

09/04/2025, 08:50

In mechanical engineering, structural vibrations are one of the primary causes of sound radiation. Given the growing demands for environmental protection, Noise, Vibration, and Harshness (NVH) analysis has emerged as a distinct engineering discipline in recent years. To address these NVH challenges, simulations are typically employed, following a structured process generally divided into three...

294. A domain decomposition strategy for natural imposition of mixed boundary conditions in port-Hamiltonian systems

Andrea Brugnoli

09/04/2025, 09:10

In this contribution, a finite element scheme to impose mixed boundary conditions without introducing Lagrange multipliers is presented. The strategy relies on finite element exterior calculus and a domain decomposition to interconnect two systems with different causalities. The spatial domain of the dynamical system is split into two parts by introducing an arbitrary selected interface. Each...

295. Porous wall induced instabilities in compressible boundary layers

Lara De Broeck

09/04/2025, 09:30

Unstable acoustic modes in high Mach number boundary layer flows contribute to the laminar-turbulent transition and play an important role in boundary layer noise emission. Therefore, we investigate the influence of porous wall linings on the acoustic modes in high-velocity boundary layers. These porous walls, which are characterized by their porosity and porous layer thickness, are commonly...