Elementary Study On Wall Skin Friction Reduction Of Symmetrical Body By Microbubbles In Boundary Layer Of Fluid

Vessel is the best conveyance on the aspect of saving energy, but decreases theenergy expends of vessel is very important as the water transportation possesses agood-sized proportion in world trade. Minish the ship resistance and improve theheadway is necessary.When large dimension objects such as airplanes and ships move with high speed inless viscosity fluid like air and water, on the solid wall a very thin layer which iscalled boundary layer will come into being, combines great wall friction resistance.This certainly will cause a great deal of depletion of energy and environmentalproblems such as air pollution and greenhouse effect, etc.The resistances which the mobile in fluid suffered are friction resistance,viscosity resistance and wave resistance, different method of decreasing resistance fitto different resistance. The ships with large carrying capacity such as oil tanker, orecarrier play important roles. The characterisitics of these ships are large hull and slowheadway. Among the components of their resistance, the wave resistance on libertysurface which pro rata with the square of velocity, for the velocity is very low. So thefriction resistance possesses 80% of the total resistance, and then the decrease offriction resistance is necessary.The main purpose of this article is to discuss the mechanism of wall frictionreduction of symmetrical body by microbubbles theoretically, and to establish anintegrated mathematics model which fits to practical application.At first, this article introduced the domestic and international theoretic andexperimental research actuality of wall friction reduction by microbubbles, andelucidated the definition and layered structure of boundary layer of fluid and theaffections of friction reduction made by the structure of the layers respectively;andthen discussed the two-phase equations and their items and presented someappropriate complementary equations, and put forward a new bubble-consideredmathematical model and concerned theory in two-phase turbulence field, and solvedthe two-phase equations by difference mesh method;finally, the author made asum-up of the whole research, and presented the research conclusion.