Carefully executed numerical simulations can virtually replace the experimental measurements. Several challenges are existed in the numerical simulation of turbulent two-fluid systems. On one hand, turbulence itself remains an unsolved problem because our traditional conceptual and technical tools are inadequate. On the other hand, the physical properties are varied abruptly across the interface forming a discontinuity in the system and affecting the associated physical processes such as breakup and coalescence of interfaces. Moreover, the modeling of the interfacial turbulent normal and tangential stresses is still an open issue that remains to be solved.