English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We construct a novel Lagrangian representation of acoustic field theory thatdescribes the local vector properties of longitudinal (curl-free) acousticfields. In particular, this approach accounts for the recently-discoverednonzero spin angular momentum density in inhomogeneous sound fields in fluidsor gases. The traditional acoustic Lagrangian representation with a ${\itscalar}$ potential is unable to describe such vector properties of acousticfields adequately, which are however observable via local radiation forces andtorques on small probe particles. By introducing a displacement ${\it vector}$potential analogous to the electromagnetic vector potential, we derive theappropriate canonical momentum and spin densities as conserved Noethercurrents. The results are consistent with recent theoretical analyses andexperiments. Furthermore, by an analogy with dual-symmetric electromagneticfield theory that combines electric- and magnetic-potential representations, weput forward an acoustic ${\it spinor}$ representation combining the scalar andvector representations. This approach also includes naturally coupling tosources. The strong analogies between electromagnetism and acoustics suggestfurther productive inquiry, particularly regarding the nature of the apparentspacetime symmetries inherent to acoustic fields.

Acoustic versus electromagnetic field theory: scalar, vector, spinor representations and the emergence of acoustic spin