1. A method for simulating a fluid flow that includes a laminar to turbulent boundary layer transition on a computer, the method comprising: performing a first calculation for a laminar boundary layer flow; performing a second calculation for a turbulent boundary layer flow; comparing a result from at least one of the first and second boundary layer calculations to a criterion; selecting, for at least some of multiple elements representing at least one of a surface and a fluid near the surface, the results of the first calculation for a laminar boundary layer flow or the results of the second calculation for a turbulent boundary layer flow based on a result of the comparison; and simulating activity of a fluid in a volume, the activity of the fluid in the volume being simulated so as to model movement of elements within the volume, the simulation being based in part on the selected results for the multiple elements.