The primary task of this work package is to implement an experimental setup that enables the measurement of the flow field around two bodies.

The goal of the work package is two fold.  They are:

1. To provide experimental data and information about the flow field around two floating bodies to be able to better understand the flow dynamics around the bodies.
2. To work closely with the Computational Fluid Dynamics work package (WP1) so as to be able to provide experimental data for verification purposes of the CFD simulations.

The goals from this work package will primarily rely on the PIV technique to measure the flow fields.  Using PIV, the time varying flow field around and in-between two bodies situated side-by-side will be measured and thus analysed. PIV results give an instantaneous three velocity component flow field measurements over a two dimensional measurement areas.  Details of the system and capabilities are given below.

• Dantec Dynamics 2C/3C PIV  FlowMap system.
• Acquisition rates of up to 100Hz can be achieved, limiting factor being the laser pulse frequency
• Fields of view of 45cm x 35cm can be realized, limiting factor being the laser energy.
• The system is submersible and can be used in towing tanks.

Initially, the goal is to have measurements of the time evolving flow field for situations that replicate the conditions and criteria utilised in WP1, enabling a direct comparison of the experimental and computational results.  Additionally, the measurements will also be extended to conditions beyond the scope of computational studies e.g. turbulent flow conditions, or relative motion between the two ships, to complement the understanding of the flow around multiple body motion. 

Experiments to be done in the latter part of 2007 and in 2008, will be done using simplistic block models that are also being investigated in WP1 and will look similar to that shown in Figure 1. 

Figure 1: Simplistic Block Arrangement to represent the two ship bodies

The region of interest for the PIV measurements is the region between the two vessels as shown in Figure 2.

Figure 2:  Diagram showing region of PIV measurement.

Also of interest is the area between the two vessels along the length of the vessels as shown in Figure 3.  These measurements are tentatively planned for 2009, and more realistic hull shapes may be considered.

Figure 3:  Longitudinal area of interest between the two bodies