Without any kind of protection ship hulls, offshore installations as well as scientific devices and sensors will immediately be colonized by marine organisms. There are different concepts to minimize or avoid this so-called "biofouling". In the past, ship hulls and underwater constructions were often coated with toxic materials to prevent biofouling. Recent developments follow different strategies based on non-sticky coatings or so-called „contact-release” effects. These effects are based on the low adhesive power between organisms and the coating, in a way that the individual weights of the organisms or hydrodynamic forces achieve a separation. Today, our knowledge about current-induced forces that are working on the colonizing organisms are only limited.

To conduct appropriate experiments, we developed and built a circular current flume, which could generate current speeds of up to 12 m/s. Current characteristic in the working field have been thoroughly examined with Laser-Doppler-Anemometry and Particle Image Velocimetry. The flume performance and the registration of data is partly automated and controlled by a PC.

At present, the flume is used for two kinds of investigations:

(1) Analysis of the hydrodynamic forces which work on barnacles (Cirripedia)

Organisms are placed inside the flume and exposed to defined current velocities. A multi-axis power sensor is used to assess forces simultaneously acting in different directions.

(2) Analysis of the performance of environment-friendly underwater coatings

Objects with different geometrical shapes or artificial organisms are placed on coated plates and introduced into the flume. Current speeds inside the flume are then slowly raised until these objects separate from the substratum or the maximum current speed of the flume is reached.

Contact: N. Lochthofen