We have the equations, its the computing power that is the limiting factor. You can do a full DNS (direct numerical simulation) of fluids on the order of a few

We have the equations, its the computing power that is the limiting factor. You can do a full DNS (direct numerical simulation) of fluids on the order of a few cubic meters. That will simulate flow to the particle, and fully turbulent, with Reynolds numbers (Re) on the order of 10^6 (IIRC). Re goes up proportional to length scale, so if you want to do a km or so, multiply this by 10^2. This is way ocean models parameterize turbulence (large eddy simulations (LES), and Reynolds Averaged Numerical Simulation (RANS) for example). It's also why observational oceanography is still done.