Towards modelling of fluid flow and food breakage by the teeth in the oral cavity using smoothed particle hydrodynamics (SPH)

The mechanical functions of the oral cavity, such as chewing and swallowing, present many modelling challenges. Plastic strain and fracturing occur in food due to interactions with hard and soft tissues, whilst the food moves, collides and mixes with fluid. Smoothed particle hydrodynamics (SPH) is a meshless numerical method that uses particles instead of meshes to discretise material. The Lagrangian nature of SPH means that it is well suited to modelling complexities such as fluid-free surfaces or solid fracture, interactions with complicated deforming boundaries, and temperature and chemical dynamics. We propose a combined SPH-biomechanical model of the oral cavity and present five model applications that address a broad range of material behaviours observed during eating. Interactions between the gums, teeth and the moving tongue with fluids in the anterior oral cavity; biting and chewing of elastoplastic foods; and biting and crushing of brittle foods are each simulated. In each case, the proposed meshless SPH-biomechanical model was found to be well suited to modelling the complex motions, boundary interactions and material responses. The modelling framework shows promise as a tool for simulation of food breakdown and taste release for foods of different material behaviours.