Kinematic viscosity (nu)

Kinematic viscosity nu is the dynamic viscosity mu divided by density rho, nu = mu / rho, with SI units of m^2/s. It is the property that sets the Reynolds number Re = V L / nu, so it controls boundary-layer behavior and the friction scaling between model and ship. For standard fresh water at 15 degrees Celsius nu is about 1.139e-6 m^2/s and for standard sea water about 1.188e-6 m^2/s; ITTC publishes the temperature-dependent values used to compute Re consistently in resistance tests. Because nu of water barely changes between model and ship while length and speed change greatly, the model always runs at a far lower Reynolds number than the ship.