Flow modeling is an indispensable tool in reducing risk for industrial problems involving fluid flow. The field of flow modeling can be broken down into numerical modeling and experimental, or physical flow modeling. Numerical models may be one-dimensional, two-dimensional, or fully three-dimensional. The latter is generally referred to as Computational Fluid Dynamics (CFD), and involves the breaking down of the geometric domain of interest into a large number of computational cells, then using a powerful computer (or series of computers) to solve the equations of motion for the fluid in each cell. Physical flow modeling entails the construction of a model, typically scaled so that the relevant geometry is smaller than the real-world prototype. Scaling laws are employed to make sure that the physical flow model behaves similarly to the full size prototype. Gas flow modeling efforts (also referred to cold flow modeling) are often deployed to industrial gas flow systems (such as air pollution control equipment), while hydraulic physical flow modeling efforts address liquid flow systems, particularly when a free surface is involved in the problem, such as a dam spillway or a wastewater pump station.