Most classical finite difference schemes for the solution of mold filling problems require orthogonal grids to represent a curved or a tapered gating system or round-shaped castings. This results in zigzag outlined interfaces or stair-like meshesin the calculation domain, which may have a pronounced effect on the calculated mold-filling behavior. In this paper, the mold filling of a thin vertical plate casting with four different gating systems has been studied by using both experimental andnumerical techniques. The gating systems examined are a curved one, a structure with one 90-degree angle between the downsprue and the runner, a zigzag-shaped design and a stair-like runner. The filling behavior of Ii quid cast iron has been observedthrough a heat-resistant window.Both experiment and simulation demonstrate the marked influence of these stair-like grids on mold filling. The experiments show that the kinetic energy loss of the flowing metal is minimum in a curved gating system, and increases tremendously in astair-like runner. However, simulation of metal flow in a curved gating system composed of orthogonal brick cells artificially introduces a substantial energy loss. As a result, the filling pattern becomes completely different from the experimental onewith a curved runner. Consequently, it is impossible to simulate, correctly, the mold-filling behavior in a curved gating system by means of orthogonal grids.A three-dimensional finite volume scheme, based on orthogonal curvilinear coordinates, has been developed. This method, which can deal with a structured non-orthogonal mesh, permits to use a body-fitted grid. The calculation domain is constructed withskew hexahedral cells, which allows to represent the casting geometry exactly. In this way, the simulation conditions are much closer to reality, and lead to calculation results that are in good agreement with the experiments.
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