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UID:0-1574@aerospace.technion.ac.il

DTSTART;TZID=Asia/Jerusalem:20260713T133000

DTEND;TZID=Asia/Jerusalem:20260713T143000

DTSTAMP:20260614T074113Z

URL:https://aerospace.technion.ac.il/events/seminar-ohad-haftka-13july2026
 /

SUMMARY:Sound Transmission Through a Slitted Wall at Non-Continuum Conditio
 ns
DESCRIPTION:Lecturer:Ohad Haftka\n Faculty:The Stephen B. Klein Faculty of 
 Aerospace Engineering\n Institute:Technion – Israel Institute of Technol
 ogy\n Location:Classroom 240\, 1st floor\, Aerospace Eng. building\n Zoom:
  https://technion.zoom.us/j/98372598857\n Abstract: This talk presents a s
 tudy of the transmission of sound waves through periodically slitted walls
  in regimes where the characteristic aperture size and acoustic wavelength
  are comparable to the molecular mean free path of the gas. The acoustic f
 ield is generated by small-amplitude normal oscillations of a vibrating wa
 ll located upstream of the perforated plate.\nThe problem is investigated 
 across the full range of gas rarefaction rates\, combining free-molecular 
 and continuum-limit analyses with direct simulation Monte Carlo (DSMC) cal
 culations.\nThe results indicate a qualitative transition in the directivi
 ty of the acoustic field with gas rarefaction. Under free-molecular condit
 ions\, the transmitted field is strongly anisotropic\, owing to geometrica
 l filtering of molecular velocities by the slits. In the continuum limit\,
  collisions promote isotropy in the molecular velocity distribution\, such
  that each slit behaves as a localized mass monopole source.\nIn cases whe
 re the wall slits are sufficiently close\, non-monotonic variations in tra
 nsmission with slit spacing are observed\, representing Rayleigh's anomaly
 \, which gives rise to extraordinary transmission.\nThis behavior is consi
 stently captured by both DSMC simulations and continuum-limit predictions.
 \nMulti-slit interactions are attenuated strongly by rarefaction\, and ext
 raordinary transmission is not observed at highly rarefied conditions.\n\n
 This work is towards an M.Sc. degree under the supervision of Assoc. Prof.
  Avshalom Manela of Aerospace Engineering\, Technion. Coadvisor: Dr. Yaron
  Ben-Ami\, Wolfson Centre for Mathematical Biology\, Mathematical Institut
 e\, University of Oxford.\n Details: \n 
CATEGORIES:Seminars
LOCATION:Classroom 240\, 1st floor\, Aerospace Eng. building

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