Freezing front propagation on microgrooved substrates

An experimental and numerical study of a planar freezing front propagating in a water layer above microgrooved substrates is presented. Classical photolithographic technology is employed to fabricate the microgrooves, and the morphological effect on the front propagation speed is quantified and compared with that predicted by the numerical simulation. The simulation is performed using enthalpy method and the finite element analysis package FIDAP in order to understand the physical mechanisms. The experimental results show that the speed of a freezing front oscillates when the front moves across the adjacent crests and troughs of microgrooves. The propagation speed on crests is about two to eight times that in troughs. The simulation results agree well with experiments and demonstrate that the silicon crests change the heat transfer direction into vertical as the latent heat is released from the freezing front, leading to a fast propagation on crests. The shape of the freezing front, the impact of the sample geometry, and the cooling rate of the system are also reported and discussed. The findings provide insight into how the speed and shape of a freezing front can be manipulated and might find broad application in systems with solidification.