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SUMMARY:Ultrasonic wave transport in strongly scattering resonant suspensi
 ons - Thomas Brunet (University of Bordeaux)
DTSTART:20230522T151500Z
DTEND:20230522T160000Z
UID:TALK198850@talks.cam.ac.uk
DESCRIPTION:The key transport parameters of acoustic waves travelling in d
 isordered media are studied through ultrasonic experiments on monodisperse
  resonant suspensions. Through accurate measurements of both ballistic and
  diffusive transport over a wide range of frequencies\, we show that the g
 roup velocity of the ballistic component may differ significantly from the
  energy velocity of the diffusive waves\, in particular in the vicinity of
  scattering resonances [1].\nFor dilute systems made of liquid scatterers\
 , we present evidence for the crucial role played by the refractive acoust
 ic index of the droplets relative to the surrounding media by studying res
 onant emulsions made of &ldquo\;slow" fluorinated oil droplets or &ldquo\;
 fast" liquid metallic droplets [2]. Our observations are successfully expl
 ained by theories based on Independent Scattering Approximations relevant 
 for these diluted media.\nHowever\, we show that ISA fails as soon as the 
 volume fraction is higher than 10%. For these concentrated disordered reso
 nant suspensions\, the transport of the multiply scattered waves becomes s
 ub-diffusive in the vicinity of resonances as predicted by Self-Consistent
  Theory [3] and can be localized in some specific cases that we will discu
 ss at the end of the talk.\n&nbsp\;\n[1] B. Tallon\, T. Brunet\, and J.H. 
 Page\, Physical Review Letters 119\, 164301\, 2017\n[2] B. Tallon\, T. Bru
 net\, J. Leng\, and J.H. Page\, Physical Review B 101\, 054202\, 2020\n[3]
  B. Tallon\, T. Brunet\, and J.H. Page\, under revision for Physical Revie
 w B\n&nbsp\;
LOCATION:Seminar Room 1\, Newton Institute
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