Challenges for PIV in towing facilities

Particle Image Velocimetry (PIV) has proven world-wide to be a promising flow measuring technique for maritime fluid dynamics research. PIV visualizes the spatial structure of steady and unsteady flows and delivers data sets for validation of numerical Computational Fluid Dynamics (CFD). This technique is supplementary to other flow measuring techniques, for example, paint tests, pitot tubes and Laser Doppler Velocimetry. Over the last 5 years various PIV measurement campaigns have been conducted at MARIN with the Sirehna-MARIN PIV system. This modular PIV system has been used in multiple configurations, for various purposes and in different towing facilities. The paper presents an overview of the most important projects, typical results and the major findings. During these test campaigns the PIV technique has shown its strengths but also its weaknesses. In this paper both aspects are discussed. A next challenge is to improve the PIV-system and the measuring and analyzing procedures converging PIV to a standard tool for towing facilities. The aim for the future is to perform PIV tests at low operational cost which will be an essential condition to increase the use of PIV for the maritime market. The detailed information about the spatial structure and dynamics of a flow obtained with PIV can be used for validation of numerical CFD-codes and to improve the design of ships and propulsion systems. Besides this, there are still other challenges left for PIV in towing facilities, for example time-resolved PIV, measuring near the ship hull or around free-sailing, manoeuvring ships.