Modeling mesoscopic solidification using dissipative particle dynamics

Dissipative particle dynamics with energy conversion (DPDe) is a simulation technique that has been used to model thermal transport characteristics and heat transfer at mesoscale. This study shows further development of the DPDe method capturing solid/liquid phase-change phenomena and its application to water freezing in a parallel-plate straight channel. In this work, the weighting functions of the random and dissipative forces are modeled as functions of temperature in order to correctly predict the temperature dependent properties of the fluid in a two-dimensional domain. An equation of state is incorporated in the model in order to model the solidification of water. Careful consideration is taken to couple the latent heat of the system to real world units, and the solidification predicted using this model is compared to a well known analytical solution. The developed model is employed to simulate the thermally developing flow in a parallel-plate channel with constant wall temperatures below the freezing point. A liquid pump is introduced along with a region initiating the liquid temperature in order to create the thermally developing flow. The investigations show that the fluid velocity has a small effect on the time it takes for the channel to freeze completely. The dominating factor will be the temperature of the solid walls in the domain. The simulations also show that when a higher wall temperature is applied, the solid/liquid interface will be rougher due to mesoscopic fluctuations of heat and momentum.