When considering flows with multiple fluids such as free surface flow and multiphase flow, an interface tracking scheme or an interface capturing scheme is required for treatment of the interfaces. The latter is more popular with CFD community due to its adaptability to different flow structures and different kinds of grids as well as its good computational efficiency. The THINC scheme is an interface capturing scheme which was originally developed for use with Cartesian grid flow solvers. Since the method provides an algebraic model for the transition between different fluids it becomes relatively easy to compute the convective fluxes which is the target of advection schemes. In this work, we apply an unstructured grid extension of the THINC scheme, UMTHINC scheme, to our newly developed unstructured grid flow solver for free surface impact problems. The efficiency and accuracy of the proposed method is investigated by applying it to some standard benchmark cases on dam break problem with an obstacle. Both two and three dimensional simulations are carried out and the results are compared to experimental data wherever possible.