1. A computer-implemented method, comprising: accessing a database having a data representation of a fluid system, the fluid system having a system boundary, at least one interior cell with a plurality of interior cell faces and at least one ghost cell with a plurality of ghost cell faces; determining a physical volume value and a physical surface area value for at least one interior cell and at least one ghost cell; generating at least one control volume based on one or more physical volume values; generating at least one control surface area based on one or more physical surface area values; substituting one or more of the at least one control volume and the at least one control surface area for corresponding elements of mathematical conservation equations representative of the fluid system; and generating a model of the fluid system based on solutions to the mathematical conservation equations.