ABSTRACT
For computational purposes we assume the bone sample is a rectangular parallelepiped and the ultrasound transponder produces on the bone surface a sinusoidal plane wave signal. The transponder and receiver are situated on the opposite sides of the sample. Two kinds of boundary conditions are assumed on different sides of the parallelogram; for example, a free-surface boundary condition is applied on all sides except the receiver side, as in. In order to make a good impedance match where the receiver is, an absorbing layer is attached at the boundary there. There are various options of absorbing layers. The one we used is called a perfectly matched layers. The perfectly matched layer (PML) is an artificial region attached to the boundary of the domain. Theoretically, the interior area and the absorbing region are perfectly matched and no reflection is generated on the interface between the two media. The idea of a PML can be viewed as an equation-splitting procedure.
