The interface tracking method—VOSET(coupled VolumeofFluid and Level Set method)combines the advantages and overcomes the disadvantages of VOF and Level Set.In this method

VOF was used to capture interfaces

which can completely keep the massconservation and overcome the disadvantage of massnonconservation in Level Set.A geometrical operation was used to calculate the Level Set function near interfaces

which could be used to compute the accurate curvature and smooth the discontinuous physical quantities near interfaces

then

the disadvantage of VOF

inaccuracy of curvature and bad smoothness of discontinuous physical quantities near interfaces

could be overcome.Therefore

VOSET was more accurate than VOF and Level Set.In this paper

VOSET was used to simulate the rising and coalescence of two or multigas bubbles.Mass conservation

feasibility of iterative geometric operation and stability of solution process of VOSET were analyzed for these complex twophase flow problems.