As network modeling becomes more widely used in real engineering problems, we will see added complexity in the shapes of simulation domains and in the boundary conditions that need to be imposed during flow modeling. A good example is the propped fracture shown on the right. The network structure (of the sphere packing) must conform to the geometry of the bounding walls, and if there is fluid exchange across the fracture walls, this needs to be reflected in boundary conditions imposed during flow simulation.

Network generation for complex boundaries is relatively straightforward for algorithms that operate on voxel images. However, modeling complex boundaries will be most important for the algorithms that operate on computer-simulated structures (such as sphere packings) because of the limited size of voxel data sets.

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