The structure of the internal wave Mach front generated by a point source moving in a stratified fluid

The height and velocity of an internal wave (IW) generated by a point fluid source moving horizontally in a stratified fluid is calculated at asymptotically large distances behind the source, in linear approximation. Particular emphasis is given to the region near the Mach front, defined by the off-track angle θ_M = sin^-1(c_M/V), where c_M is the speed of the fastest IW and V is the source velocity. To elucidate the asymptotic IW profile in that regime, a novel uniform asymptotic expansion is developed which is valid on both sides of the Mach front. It is found that, for the fluid model employed, the asymptotic approximation for the IW height, as well as for all its derivatives, is continuous at that front, and that all these IW profiles are remarkably smooth and slowly varying functions of off-track distance in that regime.