Lewin Stein

Lewin Stein
Zuse-Institut Berlin | ZIB · Department of Parallel and Distributed Systems

Dr. rer. nat.

About

19
Publications
6,073
Reads
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39
Citations
Additional affiliations
December 2018 - June 2020
Technische Universität Berlin
Position
  • PostDoc Position
October 2013 - present
Technische Universität Berlin
Position
  • Research Assistant
Description
  • Aeroacoustics 1-2 (15WS 16SS 18WS) Computational Aeroacoustics (19SS 20SS) Computational Thermo-Fluid Dynamics 1-4 (14WS 15SS 17WS 18WS) Gasdynamics 1-2 (16WS 17SS)
September 2013 - December 2018
Technische Universität Berlin
Position
  • Research Assistant
Education
September 2013 - December 2018
Technische Universität Berlin
Field of study
  • Physical Engineering
October 2010 - March 2013
Technische Universität Berlin
Field of study
  • Physics
March 2010 - September 2010
University of Freiburg
Field of study
  • Physics

Publications

Publications (19)
Article
Full-text available
The determination of optimal geometric arrangements and electronic drives of loudspeaker arrays in sound reinforcement applications is an ill-posed inverse problem. This paper introduces an innovative method to determine complex driving functions, also considering complex environmental conditions. As an alternative to common frequency domain method...
Article
Full-text available
Acoustic models of resonant duct systems with turbulent flow depend on fitted constants based on expensive experimental test series. We introduce a new model of a resonant cavity, flush mounted in a duct or flat plate, under grazing turbulent flow. Based on previous work by Goody, Howe and Golliard, we present a more universal model where the const...
Thesis
Full-text available
When gas flows along a surface containing a cavity or gap, this fluid-dynamical process is likely linked with acoustical effects. Primarily, in the transport and energy sector, the phenomenon occurs frequently: gas flows around land and air vehicles or streams inside duct systems and engines. A key challenge for these examples is either to prevent...
Chapter
The identification of sound sources is a common problem in acoustics. Different parameters are sought, among these are signal and position of the sources. We present an adjoint-based approach for sound source identification, which employs computational aeroacoustic techniques. Two different applications are presented as a proof-of-concept: optimiza...
Article
Full-text available
An adjoint-based approach for synthesizing complex sound sources by discrete, grid-based monopoles in finite-difference time-domain simulations is presented. Previously, Stein, Straube, Sesterhenn, Weinzierl, and Lemke [(2019). J. Acoust. Soc. Am. 146(3), 1774-1785] demonstrated that the approach allows one to consider unsteady and non-uniform ambi...
Chapter
The present project studies the sound pressure inside an acoustic resonant cavity driven by turbulent flow. With this numerical study as an interim result, the ultimate goal is to improve the industrial layout of resonant cavities, in general: For example to circumvent resonance conditions. The current rise of high-performance computing allows us t...
Conference Paper
Full-text available
The determination of the electronic drive of line source arrays is an ill-posed inverse problem. The authors present an adjoint-based approach in the time domain as an alternative to the commonly used frequency-based methods. Therein, monopole sources in the Euler equations are optimized to reinforce a prescribed target sound field. In doing so, dr...
Preprint
Acoustic models of resonant duct systems with turbulent flow depend on fitted constants based on expensive experimental test series. We introduce a new model of a resonant cavity, flush mounted in a duct or flat plate, under grazing turbulent flow. Based on previous work by Goody, Howe and Golliard, we present a more universal model where the const...
Conference Paper
Full-text available
To date, acoustic models of duct systems with turbulent flow depend on fitted constants/expansive test series. We present a more universal model; its constants are replaced by physically significant parameters with a clear definition. For the user, this allows an intuitive sense how a modification of design parameters affects acoustic properties....
Preprint
Full-text available
The present project studies the sound pressure inside an acoustic resonant cavity driven by turbulent flow. With this numerical study as an interim result, the ultimate goal is to improve the industrial layout of resonant cavities, in general: For example to circumvent resonance conditions. The current rise of high-performance computing allows us t...
Conference Paper
Perforated linings backed by arrays of Helmholtz resonators are well-established as silencers of tonal noise in a turbulent flow environment. Possible areas of application are the exhaust system of automotive combustion engines or the intake, bypass, and outlet of jet engines. Typically, these devices operate at subsonic and low-frequency condition...
Chapter
Helmholtz resonators play a key role as silencers in many technical applications. The aim of this work is to study the mechanism that governs the emission and reduction of noise. For the first time, we closely monitor the interaction between the acoustic field of a Helmholtz resonator’s geometry and a fully turbulent shearing flow by a Direct Numer...
Conference Paper
Helmholtz resonators as basic elements of an acoustic liner are widely used as silencers for jet turbines, exhaust systems or concert halls. In general hollow structures do not necessarily silence tonal noise, but, on the contrary, can also cause sound: Any kind of opening towards the outside of a moving vehicle (e.g., the space between wheel and f...
Article
The Richtmyer-Meshkov instability (RMI) arises from the interaction of a shock wave with a density gradient in a fluid. The density gradient can be caused by temperature and/or species concentration. The RMI leads to strong mixing and in the case of reactive flows an existing flame will be accelerated. Such acceleration processes can lead to a tran...
Thesis
Full-text available
A so-called Richtmyer-Meshkov instability arises, if a shock wave hits a perturbed interface separating two fluids with different densities: The initial perturbation grows, splits up into two counter-rotating eddies (cover picture) and finally dissolves in turbulence. These mechanisms of shock-induced mixing can be used to increase the efficiency o...
Thesis
Full-text available
The interplay of intrinsic system dynamics and external influences that result from, e.g., the coupling to the continuum or to radiation fields is an important subject of various branches of modern physics, ranging from atomic and molecular physics to quantum optics, and quantum chaos. With the creation of Bose-Einstein condensates (BECs) of alkali...
Technical Report
Full-text available
Das Ziel der Arbeit ist es, am Modell der Ekmanspirale „Die Grundlage der windgetriebenen Meereszirkulation“ als naturwissenschaftliches Phänomen zu verdeutlichen und ein besseres Verständnis der damit verbundenen Effekte zu erreichen. Der Wind ist der Hauptantrieb der gesamten Oberflächenzirkulation. Sobald sich das Klima auf der Erde ändert und s...

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Projects

Projects (2)
Project
The project aims at advancing traditional methods for Line arrays in the frequency domain by implementing an adjoint-based approach in the time domain. www.adjointsound.tu-berlin.de/menue/start_page/parameter/en
Project
Sound generation and reduction by turbulent flow interacting with rigid structures / boundaries is widely encountered in many technical applications. Our aim is to gain a better understanding of the mechanism that governs this noise modification.