1. A method for detecting object collisions in a simulation, the method comprising: identifying a plurality of objects within a defined area; defining a plurality of grids, each comprising a plurality of defined regions, some of which individually include at least one of the plurality of objects within an associated one of the defined regions; building a data tree in which each leaf node is implemented with one of the plurality of grids; and identifying collisions between objects of the plurality of objects by searching the data tree and by considering only those objects of the plurality of objects which occupy at least one common region of the plurality of defined regions during any portion of a time step.