Towingtank

Towingtank, also known as a towing tank, is a specialized experimental facility in fluid dynamics and naval architecture consisting of a long, straight water basin in which scale models of ships, offshore structures, or other vehicles can be towed at controlled speeds. The primary purpose is to measure hydrodynamic forces and moments, characterize resistance and propulsion, and study flow patterns around hull forms under calm or wave conditions.

Typically, a model is mounted on a frame connected to a towed carriage that runs along rails above or beside the basin. The carriage pulls the model by a tow line or sting while instrumentation records forces with load cells and torque sensors. Inlet and outlet depths, temperature, and surface visualization aids are controlled.

Tests commonly include resistance measurements in calm water to determine total, frictional and wave resistance; propulsion tests for propeller performance and towing power; and seakeeping or wave tests in which regular or irregular waves are generated. Flow visualization with dyes, neutrally buoyant particles, or particle image velocimetry helps reveal complex flow structures.

Testing uses similarity laws. Froude number scaling is often applied for wave resistance, while Reynolds number effects are not fully preserved in small-scale models, requiring correction factors or complementary computational methods. Modern facilities may incorporate computerized data acquisition, automated test matrices, and sometimes wave-making devices.

Towingtanks remain a core tool in naval architecture and offshore engineering, complementing computational methods and full-scale trials. They are used worldwide for hull-form optimization, propeller and rudder studies, and validation of numerical simulations.