“…These plots are also presented below for some cases, and to evaluate the group velocity, the differentials F k ( , k) and F ( , k) were calculated numerically. The distributions of dispersion curves, phase, and group velocities are presented in the commonly used [18][19][20]23,26,[30][31][32][33]48,54,55] form of dimensionless frequency versus dimensionless wavenumber and dimensionless velocity versus dimensionless frequency, respectively. The angular frequency is normalized in the following way:…”