Block VII: Wavenumber Integration

This block specifies the wavenumber sampling in the standard SAFARI format. The critical issues involved in selecting the wavenumber sampling is described in the SAFARI manual [4], but even more detailed in Computational Ocean Acoustics [3]. The structure of this input block is as follows:

CMIN:

Minimum phase velocity in m/s. Determines the upper limit of the truncated horizontal wave- number space:

CMAX:

Maximum phase velocity in m/s. Determines the lower limit of the truncated horizontal wave- number space:

In plane geometry ( option P ) CMAX may be specified as negative. In this case, the negative wavenumber spectrum will be included with k_min=-k_max, yielding correct solution also at zero range. In contrast to SAFARI, OAST allows for complex contour integration (option J) in this case.

NW:

Number of sampling points in wavenumber space. Should be an integer power of 2, i.e. NWN=2^m. The sampling points are placed equidistantly in the truncated wavenumber space determined by CMIN and CMAX.

IC1:

Number of the first sampling point, where the calculation is to be performed. If IC1>1, then the Hankel transform is zeroed for sampling points 1,2IC1-1, and the discontinuity is smoothed.

IC2:

Number of the last sampling point where the calculation is to be performed. If IC2<NWN, then the Hankel transform is zeroed for sampling points IC2+1,NW, and the discontinuity is smoothed by Hermite polynomial extrapolation.

Automatic wavenumber sampling

RDOAST supports the standard OAST auto sampling option. The automatic sampling is activated by specifying the parameter NW = -1 and it automatically activates the complex wavenumber integration contour even though option J may not have been specified. The parameters IC1 and IC2 have no effect if the automatic sampling is selected.