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UID:0-1572@aerospace.technion.ac.il

DTSTART;TZID=Asia/Jerusalem:20260706T133000

DTEND;TZID=Asia/Jerusalem:20260706T143000

DTSTAMP:20260519T094845Z

URL:https://aerospace.technion.ac.il/events/seminar-ohad-haftka-6july26/

SUMMARY:Sound Transmission Through a Slitted Wall at Non-Continuum Conditio
 ns
DESCRIPTION:Lecturer:Ohad Haftka‬‏\n Faculty:Department of Aerospace En
 gineering\n Institute:Technion – Israel Institute of Technology\n Locati
 on:Classroom 240\, 1st floor\, Aerospace Eng. building\n Zoom: https://tec
 hnion.zoom.us/j/98372598857\n Abstract: This talk presents a study of the 
 transmission of sound waves through periodically slitted walls in regimes 
 where the characteristic aperture size and acoustic wavelength are compara
 ble to the molecular mean free path of the gas. The acoustic field is gene
 rated by small-amplitude normal oscillations of a vibrating wall located u
 pstream of the perforated plate.\nThe problem is investigated across the f
 ull range of gas rarefaction rates\, combining free-molecular and continuu
 m-limit analyses with direct simulation Monte Carlo (DSMC) calculations.\n
 The results indicate a qualitative transition in the directivity of the ac
 oustic field with gas rarefaction. Under free-molecular conditions\, the t
 ransmitted field is strongly anisotropic\, owing to geometrical filtering 
 of molecular velocities by the slits. In the continuum limit\, collisions 
 promote isotropy in the molecular velocity distribution\, such that each s
 lit behaves as a localized mass monopole source.\nIn cases where the wall 
 slits are sufficiently close\, non-monotonic variations in transmission wi
 th slit spacing are observed\, representing Rayleigh's anomaly\, which giv
 es rise to extraordinary transmission.\nThis behavior is consistently capt
 ured by both DSMC simulations and continuum-limit predictions.\nMulti-slit
  interactions are attenuated strongly by rarefaction\, and extraordinary t
 ransmission is not observed at highly rarefied conditions.\n\nThis work is
  towards an M.Sc. degree under the supervision of Assoc. Prof. Avshalom Ma
 nela of Aerospace Engineering\, Technion. Coadvisor: Dr. Yaron Ben-Ami\, W
 olfson Centre for Mathematical Biology\, Mathematical Institute\, Universi
 ty of Oxford.\n Details: \n 
CATEGORIES:Seminars
LOCATION:Classroom 240\, 1st floor\, Aerospace Eng. building

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