A wave’s group velocity is one of\u00a0its most important properties.\u00a0 It characterizes the speed at which signals can be transmitted.\u00a0 For waves traveling in a material medium, the group velocity is generally given by the differential slope of the dispersion relation (wave frequency versus wavevector).\u00a0 However, for resonant or strongly scattering media, this formula breaks down.\u00a0 In such media the prediction of group velocity thus became a classical problem in the study of waves.\u00a0 In collaboration with experimentalists at the University of Manitoba and University of Pennsylvania, we have proposed a solution to this classical problem through the use of a “spectral function approach” [1].\u00a0 In particular, the experimental results on the sonic group velocity, obtained by using the phase averaging method, exhibited very large and peculiar variations which break the theoretical bounds of the so-called effective medium theories, valid in the long wavelength regime.\u00a0 With no adjustable parameters, the spectral function approach can quantitatively explain all the measured results.\u00a0 The physical picture which emerges is that in strongly scattering media, wave multiple scattering can lead to a renormalization of the perceived medium property, which in turn can mean a “new” dispersion relation from which the group velocity should be calculated.<\/p>\n
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Key Publication:<\/strong><\/p>\n A wave’s group velocity is one of\u00a0its most important properties.\u00a0 It characterizes the speed at which signals can be transmitted.\u00a0 For waves traveling in a material medium, the group velocity is generally given by the differential slope of the dispersion relation (wave frequency versus wavevector).\u00a0 However, for resonant or strongly scattering media, this formula breaks … Continue reading Group velocity in strongly scattering media<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[5],"tags":[],"_links":{"self":[{"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=\/wp\/v2\/posts\/254"}],"collection":[{"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=254"}],"version-history":[{"count":3,"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=\/wp\/v2\/posts\/254\/revisions"}],"predecessor-version":[{"id":285,"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=\/wp\/v2\/posts\/254\/revisions\/285"}],"wp:attachment":[{"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=254"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=254"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/sheng.people.ust.hk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=254"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n