We assume that two continuous, supersonic jets of plasma advance into a uniform surrounding medium of constant density and pressure. In terms of fluid dynamics their propagation is described by the kinetic model suitable for high Mach number flows, which likely occur in edge-brightened powerful radio sources. In this approximation the jet flowing energy is dominated by the bulk energy of thermal material. The end of the jet enters the undisturbed ambient medium and forms a front shock, where the supplied bulk energy is in situ transferred to relativistic particles and magnetic field.