The formation of vortices above the submerged discharge intakes of water reservoirs is undesirable as they can suck surface debris and air into the discharge pipework. In the present work, a numerical investigation was performed on the performance of an anti-vortex device at the water intake. The numerical simulation of the flow field around a free-surface vortex was verified with experimental data, with good agreement found on radial velocity and vortex type. The lateral shape of the anti-vortex device was defined by the modelled inflection points in the vertical profile of the radial velocities. The numerical simulation presented here may also be helpful in gaining a deeper understanding of determining the intake depth required to avoid air-entraining vortices in reservoirs. It may also be useful in studying the behaviour of free-surface vortices in the presence of anti-vortex devices.

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