A three-dimensional, time-dependent numerical model of free-surface flows and heat transfer including phase change has been used to simulate the impact of a liquid droplet on a solid particle and to predict the size of the void under the solid particle caused by incomplete filling by liquid landing on top of it. The solid particle was considered to be a protrusion on the substrate. Fluid flow in the impacting liquid droplet was modeled using a finite difference solution of the Navier-Stokes equations in a 3D Cartesian coordinates assuming laminar, incompressible flow. Heat transfer in the liquid droplet was modeled by solving the energy equation, assuming densities of liquid and solid to be constant and equal to each other. The free surface of the liquid droplet was assumed to be adiabatic. The porosity in this simulation was defined as the volume of the incompletely filled void under the solid particle to the volume of the solid particle. The simulation was repeated with different process parameters, and the results showed that process parameters play significant roles in determining the amount of porosity. A correlation is found to express the porosity as a function of the process parameters.