Laser speckle correlation applied to flow field measurements in granular mediaE. Hamm and F. Melo
Departamento de Física, Universidad de Santiago de Chile and Center for Interdisciplinary Research in Materials, CIMAT Av. Ecuador 3493, Casilla 307 Correo 2, Santiago, Chile
received 8 September 2005; accepted in final form 8 December 2005
published online 24 December 2005
A laser speckle correlation method is developed to measure slow macroscopic flow fields in a randomly packed granular medium. The method is useful for planar geometry configurations like the one considered here, namely a sample that is subjected to an indentation type test. The main feature revealed by the method in this system, is the formation of shear bands of well-defined shapes, proper of a Coulomb-like material. We characterize these structures by showing that they concentrate vorticity and shear deformation. In addition, the method provides high-precision measurements of tiny displacements occurring far below shear bands.
45.70.-n - Granular systems.
42.30.Ms - Speckle and moire patterns.
© EDP Sciences 2006