一様水路の不定流

Abstract

This paper treats with the unsteady flows in prismatic open channels by the theoreticalanalysis of one dimensional equation of motion and continuity. The author has shownthat unsteady flows in an prismatic channel can classified by an index λ, where In (Hm-Ho)/I√gHmTD has the value of the order of the ratio of water stage rising or fallingspeed to the vertical component of long wave celerity.The critical value of λ, above which the wave breaks into a bore has obtained by theexpansion of h and a in power series near the wave-front. Below the critical value, thebore formation is prevented and in the case where the value of λi is the order of unityor larger the waves propagate as "dynamic" and the Saint Venant equation must bemodified for the effects of vertical acceleration, and if λi≪1 the wave is "kinematic".The author has obtained the second approximation of kinematic wave in the caseswhere λ≪1 and λi≪1 and has compared the results with that obtained directly by thecomputor.