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SD2155 Flow Acoustics 6.0 credits

About course offering

For course offering

Spring 2025 Start 14 Jan 2025 programme students

Target group

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Part of programme

Master's Programme, Engineering Mechanics, åk 1, Optional

Master's Programme, Engineering Mechanics, åk 1, TEMA, Conditionally Elective

Master's Programme, Engineering Mechanics, åk 1, TEMC, Mandatory

Master's Programme, Vehicle Engineering, åk 1, Conditionally Elective


P3 (6.0 hp)


14 Jan 2025
16 Mar 2025

Pace of study


Form of study

Normal Daytime

Language of instruction


Course location

KTH Campus

Number of places

Places are not limited

Planned modular schedule


For course offering

Spring 2025 Start 14 Jan 2025 programme students

Application code



For course offering

Spring 2025 Start 14 Jan 2025 programme students


Susann Boij (


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Course coordinator

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Headings with content from the Course syllabus SD2155 (Spring 2022–) are denoted with an asterisk ( )

Content and learning outcomes

Course contents

Mathematical tools. The fundamental equations of fluid mechanics. The classical wave equation and its solutions. The inhomogeneous wave equation. Lighthills theory for aerodynamic sound. Curles equation. The convective wave equation. Sound propagation in ducts and pipes. Multi-port theory. Sound from moving sources. (”Ffowcs Williams&Hawkings equation”). Fluid driven self sustained oscillators – Whistles. Applications with focus on fluid machines and vehicles.

Laboratory exercise: Measurement of 2-port for a muffler.

Project assignment: Analysis of an exhaust muffler.

Intended learning outcomes

To present the fundamental theories for sound generation and propagation in fluids with non-stationary (turbulent) flow fields.

Students graduating from the course should:

  • Be able to derive the classical wave equation and be familiar with the solutions under plane and spherical symmetry including Greens functions.
  • Be able to explain and apply a multipole-expansion and know the character of the simplest point sources (monopole, dipole, quadrupole).
  • Know about Lighthills acoustic analogy and its limitations and be able to explain the physical mechanisms that generate sound in a flow.
  • Know how flow and motion affects sound propagation and generation and be able to explain phenomena such as the Doppler-shift and the Mach-cone.
  • Be able to apply Lighthills analogy to fluid machines and vehicles and know how the different mechanisms scale with the flow speed.
  • Be able to explain how fluid driven self-sustained oscillators (”whistles”) are created and how they can be eliminated.
  • Be able to apply 2-port theory to analyse sound propagation in pipe and duct systems in particular with application to vehicle exhaust systems.
  • Have obtained training in experimental techniques for analysis of sound in ducts.

Literature and preparations

Specific prerequisites

Basic courses in mathematics, mechanics.

English B / English 6

Recommended prerequisites

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Examination and completion

If the course is discontinued, students may request to be examined during the following two academic years.

Grading scale

A, B, C, D, E, FX, F


  • LAB1 - Exercises, 1.0 credits, grading scale: P, F
  • LAB2 - Project, 1.0 credits, grading scale: P, F
  • TEN1 - Examination, 2.0 credits, grading scale: A, B, C, D, E, FX, F
  • ÖVN1 - Assignments, 2.0 credits, grading scale: P, F

Based on recommendation from KTH’s coordinator for disabilities, the examiner will decide how to adapt an examination for students with documented disability.

The examiner may apply another examination format when re-examining individual students.

Other requirements for final grade

Written examination (TEN1; 2 university credits), approved exercises (ÖVN1; 2 university credits) approved measurement exercises (LAB1; 1 cr) and project work (LAB2; 1 university credits).

Opportunity to complete the requirements via supplementary examination

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Opportunity to raise an approved grade via renewed examination

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Ethical approach

  • All members of a group are responsible for the group's work.
  • In any assessment, every student shall honestly disclose any help received and sources used.
  • In an oral assessment, every student shall be able to present and answer questions about the entire assignment and solution.

Further information

Course room in Canvas

Registered students find further information about the implementation of the course in the course room in Canvas. A link to the course room can be found under the tab Studies in the Personal menu at the start of the course.

Offered by

Main field of study

Mechanical Engineering

Education cycle

Second cycle

Add-on studies

SD2165 Acoustical Measurements
SD2150 Experimental Structure Dynamics
SD2175 Numerical Methods for Acoustics and Vibration
SD2180 Non-Linear Acoustics
SD2190 Vehicle Acoustics and Vibration
SG2218 Turbulence


Susann Boij (