Non-monotonic Ice-core Thawing in Water Pool Leading by Flow Competition

This study demonstrates a non-monotonic dependence between pool temperature and thawing time for the ice-core thawing problem. Numerical simulations reveal that this anomaly arises from competing convective mechanisms driven by the density-temperature anomaly at ~4°C of water. The sides come from the anomaly chaotic flow induced by boundary-core thermal gradients, and the normal natural convection stabilized by buoyancy from the density extremum near the core. As the pool temperature increases from 2.5 to 80 °C, the flow transitions from a chaotic to a steady state. Within the transitional regime, however, flow stability decreases with the Fourier number, eventually can leading to re‑chaotization. The pool size modulates the competition between chaotic flow and natural convection through the Rayleigh numbers, which govern both the extreme points in thawing time and the extent of the non‑monotonic effect, thereby enabling precise control over thawing kinetics. These insights clarify how the non‑Oberbeck–Boussinesq effects of density and viscosity govern ice‑core thawing dynamics and pave the way for advanced controlled‑thawing technologies in applications such as cryopreservation and organ resuscitation.