Hi Vernal,

Thanks for your questions. I'll try and answer them in turn.

>> I think I am mis-using k-wave here. I learned that k-wave was developed for photoacoustics and I am trying to solve ultrasound propagation in water and its scattering/reflection at the seafloor.

You are correct that the first release of k-Wave (B.01) only modelled initial value problems (of which biomedical photoacoustics is an example). However, the second release allowed pressure sources, and the third release allowed both pressure and velocity sources. Nonlinearity aside, the governing equations for both the problems you mention are identical, so you can certainly use k-Wave for this purpose.

>> I think my approach so far is modeling only specular reflection (is that correct?) whereas I'd be more interested in diffuse reflection. Any more hints about modeling that?

The type of reflection that you observe will depend on the wavelength of your source and the length scale of the scattering objects (or in your case, the length scale of the small random variations on the surface of the sea floor). If the wavelength is much smaller than the length scale of the surface variations you will observe specular reflection. Alternatively, if the length scale of the surface variations is much smaller than the acoustic wavelength, you will observe diffusive reflection.

>> k-wave tells me for each scenario what the maximum supported frequency is

This number corresponds to the maximum frequency that can be represented by two points per wavelength given your grid spacing and the sound speed in the medium (the Nyquist limit). You can calculate this frequency yourself using the formula `f_max = c_min / 2*dx`

where `c_min`

is the minimum sound speed within the medium.

>> Do I need a really fine (and therefore large) grid to have my calculations done?

Large, yes. At two points per wavelength your grid size will be 20m ~ 3300 grid points by 35m ~ 5800 grid points (in reality you will need a finer discretisation than this if you want to accurately model reflections). In 2D this is achievable if you have access to decent computational resources (~20 million elements), but if you also have a third dimension the problem will in all likelihood become intractable.

>> I should have put all this into the Ultrasound Simulation subforum.

Moved.

I hope that helps, good luck with your simulations!

Brad.