Dynamics of melting ice cylinders in a cross-flow*

The formation and release of icebergs into the ocean accounts for half of the total freshwater discharged from ice sheets (Depoorter, 2013). As icebergs float and melt far from their sources, they impose adverse effects on both local and global marine ecosystems. Despite this, present-day ice melt models frequently underpredict iceberg melt dynamics and the spread of meltwater, necessitating further research into the fundamental fluid mechanics of icebergs. In this work, we study the bluff body dynamics of ice to understand the effect of a cross-flow on ice melt and resultant meltwater spread. Experiments are completed in a closed-loop water channel for initial Reynolds numbers (Re₀=UD₀/ν) ranging from Re₀=0 to 885. Flow structures are measured using flow visualization techniques and particle image velocimetry (PIV), and melt rates are found from surface area measurements. It is found that the melt rate increases with higher Re₀; however, across all Re₀ it is found that as the ice melts, the ice shape does not remain symmetric. Rather, the resultant vortex wake leads to different local melt rates between the front and back faces, creating significant shape changes. As a result of the time-varying ice cylinder shape, results show that the formation length (L_f), wake width (W_y) and Strouhal number (St=fD/U) vary through the melt process as well as with Re₀. The results are compared to non-melting cylinders that are representative of initial and terminal ice shapes.