Applied Physics and Mathematics Annotation << Back SIMPLE WAVE DYNAMICS IN CHANNELS L.N. PYATNITSKY It is believed that a simple wave (wave Riemann) retains its properties in the channel, for example, as some gas driving by the piston in a pipe. However, the limited cross-section substantially changes the feature of the flow. Viscous friction on the wall makes the pressure local perturbations propagating as acoustic waves which fill the flow volume with a grid of parameter oscillations like velocity turbulent pulsations. In addition, the simple wave in a limited cross-section channel looks as a wave beam undergoing diff raction divergence. The external spherical layers of the waves reflected from the walls form a structure of oscillation modes as it is in the waveguide. As a result, dissipation induced by viscous friction and the wave beam divergence violate the fl ow self-similarity, so that the simple wave within the channel might be nominated as quasisimple wave. Keywords: Simple wave, piston driven, acoustic wave, turbulent pulsations, viscous friction, dissipation, wave beam diff raction divergence, self-similarity, waveguide mode. Contacts: E-mail: pyat7@mail.ru Pp. 03-08.