Acoustic: Plate Silencer and Sound Absorption

What You'll Build

This lesson walks you through a CFD simulation of a plate silencer — a device used to absorb unwanted noise across industries from automotive and power generation to mining, subway tunnels, and architectural acoustics. A silencer works by vibrating in response to incoming sound waves; when the silencer's mode shapes match the sound waves, the energy is absorbed, quieting the environment.

In this project, you'll model a symmetric silencer with a sinusoidal wavy plate at its center and study how acoustic waves behave as they travel through it — quantifying the silencer's noise-reduction efficiency.

What You'll Learn

• The physics of sound: how reciprocating air-layer vibrations above ~16 Hz produce sound, and how silencers absorb it

• How to design a 2-D symmetric silencer geometry with a wavy central plate (0.015 m wave amplitude) in Design Modeler

• How to generate a structured mesh (~17,000 elements) for an acoustic domain

• How to set up the Ffowcs-Williams & Hawkings (FW-H) acoustic model, defining far-field density (1.225 kg/m³), sound speed (340 m/s), and reference acoustic pressure (2×10⁻⁵ Pa)

• How to define acoustic sources near the inlet to introduce pressure waves

• Why this simulation must be transient (unsteady) to capture wave behavior over time

• How to apply boundary conditions including a velocity inlet, pressure outlet, and convective walls with a heat transfer coefficient

• How to use the k-ε Realizable model with enhanced wall treatment and the energy equation

• How to post-process pressure, velocity, and temperature contours, plus Sound Pressure Level (dB) vs. frequency at inlet and outlet receivers, and the all-important Transmission Loss diagram

Why It Matters

Noise control is a regulated requirement across automotive, HVAC, power, and building industries. The FW-H acoustic workflow you build here is the foundation for designing mufflers, exhaust systems, and any noise-attenuating device.