Wave Energy Control Laboratory
We're interested in
by using new and innovative technologies and concepts such as ...
1. Acoustic Black Hole
2. Acoustic Metasurface
3. Acoustic Metamaterial
4. Phononic Crystal
5. Computational Aero-Acoustics
1. Acoustic Black Hole
As lights cannot escape from a black hole, incident elastic waves cannot escape from an acoustic black hole (ABH). The ABH is a wedge-shaped structure whose thickness is reduced to zero by the power law. Owing to its extraordinary geometry, the ABH slows down the group speed of elastic waves to zero and focuses the energy of the elastic waves toward its tip. In WAVELAB, we develop mathematical theories and designs for ABHs customized to various industrial applications. For instance, we proposed an Archimedean spiral ABH to enhance the space efficiency while maintaining the damping performance of the ABH. The ultimate goal is to provide efficient passive control of structural vibrations by using a lightweight structure.
2. Acoustic Metasurface
Controlling low-frequency sound with a subwavelength-scaled structure is an important but challenging issue. The acoustic metasurface is a periodic structure that manipulates phases of low-frequency sound with ultra-thin thickness. We propose new designs of acoustic metasurface and apply such designs to many engineering problems such as perfect sound absorption.
3. Acoustic Metamaterial
A metamaterial, the word originated from the Greek latter ‘Meta’(μετά, meaning ‘after’ or ‘beyond’) and ‘Material’, is an artificial structure exhibiting a property that is not found in nature. The concept of metamaterial started from the academic fields of electromagnetics, and now further extended in acoustics (or elastic wave) fields based on the analogy between electromagnetic waves and sound waves. The precise shape, geometry, size, orientation, and arrangement of acoustic metamaterials are tailored to realize the smart properties capable of controling the wave energy such as acoustic cloak, negative refraction, perfect absorption/reflection/transmission, etc.
4. Phononic Crystal
Phononic Crystal (PnC) is an artificial crystal structure made of periodic arrangement of voids or scatterers embedded in a matrix. PnC has specific frequency ranges called phononic bandgaps which are physically explainable by the wave interference and Bragg scattering. In the frequency range of bandgaps, the wave energy cannot pass through the structure, so that PnC can be applied to noise and vibration isolation, wave guiding and filtering, etc.
5. Computational Aero-Acoustics: Fan Noise Prediction & Reduction
Fast and accurate prediction and effective reduction of noise radiated from rotating fans are very important technologies in industries. In cooperation with LG electronics, we are currently developing a program to predict the tonal and broadband fan noise with efficiency and accuracy. In addition, we are trying to apply acoustic meta-structures to reduce the fan noise effectively.
