THE SIMULATION OF DISTRIBUTED FREE GAS IN LIQUIDS USING VERWEY-YU SCHEME

摘要

Describing fluid transients in which free air is present has attracted a lot of researchrneffort in the last two decades. The numerical modeling of these flows poses specialrnproblems due to numerical dispersion and attenuation. The available methods are thernmethod of characteristics using several kinds of interpolations, implicit methods andrndiscrete methods. In 1993 a numerical scheme was suggested by A.Verwey and J.H.rnYu. This scheme was tested to be applicable in water hammer and cavitation as wellrnas fluid-structure interaction simulations. This scheme has the distinct advantage ofrnbeing stable over wide range of courant applications. It is intended in this paper to usernthis scheme in the simulation of transients in liquids with free gas. The inherent appealrnof this scheme is that it will be possible to carry out the simulation even when thernexistence of free gas in the liquid leads to reducing the wave propagation velocity,rnbenefitting from the numerical stability of the scheme. In this way it would be possiblernto avoid interpolation, which introduces numerical damping. Special attention has to bernpaid to the numerical procedure in order to reach a stable application of this technique.rnThe results show good accordance with those produced by delft hydraulic which werernused as a benchmark in order to assess the applicability of the Yerwey-Yu scheme inrnthis type of simulation.