1. A system for determining a cache optimized ordering of cells in an unstructured graph, comprising: ad bounding module identifying cells laying on a specified portion of a boundary of a logically-defined grid for a stored unstructured graph; a reordering module adding each identified cell in order of traversal along the specified portion of the boundary into an element of a provisional level set array block, and inserting one or more further cells between each sequential pair of cells, which are not contiguously-located in the logically-defined grid, into an element of the provisional level set array block, each further cell being located contiguous to at least one of the sequential pair of cells in the logically-defined grid; and an iteration module iteratively identifying, adding and inserting each cell remaining in the logically-defined grid.