Numerical towing tank

A numerical towing tank is a viscous-flow CFD simulation that reproduces a towing-tank test in software, solving the Reynolds-averaged Navier-Stokes (RANS) equations around the hull with a free-surface model (typically volume-of-fluid) to get resistance, sinkage, trim, and the wave field, and in self-propulsion mode an actuator-disk or discretized propeller to get delivered power. Run at full-scale Reynolds number it sidesteps the model-to-ship friction scaling that the physical tank needs. Benchmark hulls such as KCS and KVLCC2 with published tank data are the validation cases. It does not replace the physical tank for final powering but supports hull-form variation and scale-effect studies.