AWI: Elango Selvam joined our group as PhD student
Elango started his PhD on 15 November. He will develop an accurate numerical tool for the simulation of nonlinear elastic waves in solids, and the validation of this tool by comparison with measurement data.
Most ultrasound inspection techniques assume linear relations between the acoustic pressure and the average particle velocity. Linearity implies that the medium parameters are not dependent on the acoustic field itself. This assumption is no longer valid for high field values, and a proper description of the occurring waves requires the introduction of nonlinear medium behaviour. For elastic media, this requires the introduction of three additional medium parameters (l,m,n). To develop equipment and procedures that extract and apply nonlinear elastic data, appropriate numerical models are required to simulate the nonlinear propagation of elastic wave fields. Especially for nonlinear problems, one wants to avoid excessively dense computational grids and employ a discretisation close to the theoretical limit of two points per wavelength. It has been demonstrated that the Iterative Nonlinear Contrast Source method, developed at the Delft University of Technology by M.D. Verweij and co-workers, can accurately simulate acoustic wave propagation in nonlinear fluids using grids with slightly more than two points per wavelength.
Elango will extend the INCS method to deal with nonlinear elastic wave propagation under the supervision of M.D. Verweij.