Copenhagen Zoo, Denmark, is creating more space for its polar bears, extending the present enclosure with an entirely new 3,000 m2 facility named the Arctic Ring. Besides large dry-land areas, it will include deep- water features, as well as a glass tunnel for visitors. DHI watches over the hydraulic design of these new basins.
A majestic polar bear, diving with unexpected elegance and mobility, so close you could almost touch his floating hair – it will be a magnificent sight. At least, if the windows are clean.
“Careful hydraulic design of the polar-bear, seal and bird basins is important to mitigate algae growth on viewing windows and debris deposition on the bottom”, explains Carl Johnson from DHI. The latter is especially important for the transparent viewing tunnel, which is to be submerged in the polar-bear basin. This 3 m-diameter tunnel will give visitors a unique view into the polar bears’ underwater world. “The complex architecture of the basins, coupled with the large number and distribution of inlet jets and outtakes, made their hydraulic design a particular challenge”, Carl adds.
Fig. 1: Close polar bear encounters will be enabled in the new enclosures, creating a more open and attractive space for both the animals and the Zoo’s 1.4 million annual visitors. Copyrights: Copenhagen Zoo.
The flow conditions in the basins, including the water intakes and outlets both on the bottom and at the water surface as skimmers, were investigated by DHI applying Computational Fluid Dynamics (CFD). The open-source CFD platform, OpenFOAM®, was used in this project. A precise three-dimensional (3D) description of the basins was set up and formed the basis for the numerical flow model. Subsequently, the complex flow patterns in the basins were investigated in great detail and discussed with the Client Aqua-Teknik A/S holding the complete Design & Build contract for all water treatment systems, as well as delivery and installation of acrylic tunnel and panels. As a result of the simulations, the orientations of the in-flow water jets were modified to improve performance. In this way, DHI helped to make sure that the new underwater world, which is set to open its doors in June 2012, satisfies the needs of both bears and visitors, and allows them to take a very close look at each other.
Fig.2: Sample of simulated 3D flow field in the new basin, including the viewing tunnel.