Melting of ice balls in homogeneous isotropic turbulence

We study the melting of thermalised large-scale ice balls in different turbulence intensities. For this a dodecahedral water tank of about 210 litres is fitted with twenty numerically-controlled electric motors mounted on the vertices, which agitate the water with impellers, reaching Reynolds numbers of 10⁶. Zero-mean velocity homogeneous isotropic turbulence (0MVHIT) is achieved in an approximately 20 cm diameter volume in the centre of the dodecahedron. A hole in the top part of the tank allows particles up to 15 cm diameter to be inserted in the tank. The silhouettes of the ice balls are captured with shadowgraphy. We studied the conductive heat transfer from the turbulent water to the ice ball. We found that the Nusselt number is constant throughout the melting process, and Nu and Re are related through a power-law. The ice balls melt isotropically, maintaining sphericity. To better describe the interaction between the turbulent flow and the (melting) ball we investigated the flow with both PIV and numerical simulations.