k-Wave

1. rmurthy
   

   Member
   Joined: Nov '11
   Posts: 4

   Hello,

   When defining a Nx and Nz computational grid, what are the boundary conditions outside of the grid? Is the material at the boundary continuous and infinite outside of it? Or do we assume that there is air around the boundaries?

   And when making a point source, is there a way to make the wave propagation unidirectional? For instance, in the homogeneous material example, the wave propagates around the circle, outwards -- if I wanted a "semi-circle" wave going only to the right, how would I set that source up?

   Posted 12 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,640

   A special type of anisotropic boundary condition called a perfectly matched layer (PML) is used to absorb the waves when they reach the edge of computational domain, effectively simulating an infinite material. The characteristics of this layer (for example, whether it is inside or outside the grid size set by the user) are described in the Controlling The Absorbing Boundary Layer Example. Some references are listed in the toolbox if you want more information (Getting Started -> Reference List).

   You can define either pressure or velocity sources in k-Wave. You can think of these as mass or force sources which respectively act as acoustic monopoles and dipoles. If you are only interested in the sound propagating in one direction, you could place your source close to the edge of the domain and not worry about the wave going into the PML. Alternatively, you could think about the characteristics of the type of source you are physically trying to model, and try and implement these characteristics (for example, if the source is next to a reflecting boundary, etc.).

   Posted 12 years ago #

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