Abstrac High pressure die casting (HPDC) is an important process for manufacturing high volume and low cost components. Examples from the automotive industry include automatic transmission housings, piston heads and gear box components. In this process liquid metal (generally an aluminum alloy) is injected at high speed (around 50 to 100 m/s) and under very high pressure through complex gate and runner systems and into the die. The geometric complexity of the dies leads to strongly three dimensional fluid flow with significant free surface fragmentation. Crucial to forming homogeneous cast components with minimal entrapped voids is the order in which the various parts of the die fill and the gas exits. This is determined by the design of the gating system and the geometry of the die. Numerical simulation offers powerful insights into the effect of changes in die design and the filling process. Smoothed particle hydrodynamics (SPH) is a special type of numerical methods for simulating fluid flows. It uses only particles to represent the fluid and these are the computational framework on which the fluid equations are solved. (SPH) automatically follows complex flows and is particularly suited for high speed fluid flows that involve droplet formation, splashing and complex free surface motion such as those found in HPDC. In this thesis the (SPH) and use of (SPH) for simulation of casting process is described. Comparison of SPH and Volume of fluid (VOF) simulation with experimental results of water analogues are made for casting process. Other results about heat transfer by SPH in this investigation are discussed. Also the natural convection problem is solved in square enclosure by three different Ra number. The fluid flow and temperature contours are compared with flow_3D soft results. Generally the obtained results have good agreements by reference results and show that SPH is able to predict the structure of the filling process and heat transfer in the casting process. Key Words SPH, casting, heat transfer, VOF