Session G32: Focus Session: Culinary Fluid Dynamics

Culinary fluid mechanics and other currents in food science

Innovations in fluid mechanics are leading to better food since ancient history, while creativity in cooking inspires applied and fundamental science. In this talk, I will discuss how recent advances in hydrodynamics are changing food science, and how the surprising phenomena that arise in the kitchen lead to discoveries and technologies across the disciplines, including rheology and soft matter. Central topics include cocktails and champagne (multiphase flows), whipped cream (complex fluids), and pancake making (viscous flows). For every subject, I will present state-of-the-art knowledge, open problems, and likely directions for future research.   

Crack Propagation Mechanism of Freeze-Dried Soybean Curds during the Rehydration Process

The rehydration of a porous freeze-dried food plays a crucial role as it significantly influences the quality of the final product. In this study, we investigated the rehydration of freeze-dried soybean curd, commonly known as tofu, and elucidated the mechanism of crack propagation during the rehydration process. We rehydrated the freeze-dried tofu samples with water at four different temperatures ranging from 20 °C to 100 °C. The rehydration time, defined as the time taken to completely wet the entire surface of the sample, decreased with an increase in water temperature. We found that the cracks, formed during the production process, absorbed water significantly faster than the porous body. Interestingly, the crack expanded when immersed in high temperature water, leading to the breakage of the tofu. Environmental scanning electron microscopy revealed that tofu expands as it absorbs a significant amount of water. We concluded that the crack expansion in high-temperature water is attributed to the stress concentration caused by the difference in water rehydration rates between the cracks and porous body.   

Dancing Raisins: Levitation and Dynamics of Bodies in Supersaturated Fluids

Bodies immersed in gaseous fluids are natural sites for the nucleation of bubbles. These bubbles confer the bodies with additional buoyancy which can lift them upward against gravity. But a free-surface can clean the body of these lifting agents as the gas escapes which may result in plummeting, as the body begins the process anew. Experiments using fixed and free immersed bodies reveal fundamental features of force development. A continuum model which incorporates the dynamics of a surface buoyancy field is used to predict the ranges of body mass and size, and fluid properties, for which the system is most dynamic, and those for which body excursions are suppressed. Body rotations at the surface are found to be critical for driving periodic vertical motions of large bodies, which in turn can produce body wobbling and multi-period excursions.