Rarefied flows cannot be accurately simulated using Navier-Stokes (N-S) equations. The Direct Simulation Monte-Carlo (DSMC) technique is a particle based method for accurate simulation of flows under such conditions. A DSMC code is developed using an object-oriented (OO) approach which can simulate flows around arbitrary shapes. Hence, the flux from such boundaries can be correctly predicted. The object-oriented approach enables for easy modification of the code. For example, it is easy to use different collision models to implement different relaxation algorithm. The code is validated for the one-dimensional Fourier heat conduction problem. Results for the development of a shock due to supersonic flow over a 15 degree wedge are also presented. Inclined boundary of the wedge is correctly captured as the particles interact with the the exact shape of the boundary. Shock angle is found more than expected due to rarefaction effects.