BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Mechanistically evaluating the local Bloch wave approximation in g
 raded arrays of vertical barriers - Ben Wilks (University of Otago)
DTSTART:20230525T151500Z
DTEND:20230525T160000Z
UID:TALK198931@talks.cam.ac.uk
DESCRIPTION:Wave interaction with graded metamaterials exhibits the phenom
 enon of rainbow reflection\, in which broadband wave signals slow down and
  separate into their frequency components before being reflected. This phe
 nomenon has been qualitatively understood by describing the wave field in 
 the metamaterial using the local Bloch wave approximation (LBWA)\, which l
 ocally represents the wave field as a superposition of propagating wave so
 lutions in the cognate infinite periodic media (so-called Bloch waves). We
  evaluate the performance of the LBWA quantitatively in the context of two
 -dimensional linear water-wave scattering by graded arrays of surface-pier
 cing vertical barriers. To do this\, we implement the LBWA numerically so 
 that the Bloch waves in one region of the graded array are coupled to Bloc
 h waves in adjacent regions. This coupling is computed by solving the scat
 tering of Bloch waves across the interface between two semi-infinite array
 s of vertical barriers\, where the barriers in each semi-infinite array ca
 n have different submergence depths. Our results suggest that the LBWA acc
 urately predicts the free surface amplitude across a wide range of frequen
 cies\, except those just above the cutoff frequencies associated with each
  of the vertical barriers in the array. This highlights the importance of 
 decaying Bloch modes above the cutoff in rainbow reflection.
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR