Volume Fraction Conservation Method

Many free-surface flows problems exist in engineering practice, so there is very importance engineering value and academic meaning to make scientific researches on free-surface flows. Numerical simulation is one of the primary methods to study and solve engineering problems. Because of special quality of free surface, the disposal of free surface becomes more difficult and important in numerical simulation. This paper studied the free-surface reconstruction in the VOF method so as to track the free surface accurately.In this paper kinds of methods to solve the problem of the free-surface flows were reviewed firstly, especially those methods of numerical calculation, and their advantage and also the disadvantage were analyzed respectively, and then the VOF method which was applied to track the flowing of free-surface was introduced in detail.In order to track the free-surface more precisely and simulate the deformation of complex free-surface, the VOF method was improved. The author developed a modified free-surface reconstruction method which was named with the fractional volume conservation of fluid. Under the suppose that the borderline was continuous and there was only one sloped line in a boundary mesh, it was using continuous sloped line segment to reconstruct free surface in a boundary mesh. The equations were listed out according to the fractional volume of fluid and the intersection of the borderline and mesh. Then the surface was reconstructed by solving the equations. The algorithm was simple and was able to achieve in computation. It enhanced the ability of VOF method to deal with the complex free-surface flows and could track the free surface more accurately.This paper provided some models to contrast the new algorithm and the other common methods. The computational results indicated that it was more efficient than other methods for reconstructing free surface.