A 3D swallowing simulation using smoothed particle hydrodynamics

A three-dimensional (3D) computer simulation of swallowing is presented. The soft structures (i.e. pharyngeal wall, soft palate and tongue) are simulated using finite element models. Bony structures (e.g. mandible, hard palate and hyoid) are simulated as rigid bodies. A fluid bolus is simulated using smoothed particle hydrodynamics (SPH). A Newtonian viscosity model is validated by comparing a 3D SPH simulation of Hagen-Poiseuille flow with theoretical results. A previously unreported source of error is reported and discussed. In the swallowing simulation, fluid boundaries are determined by the rigid and deformable surfaces, and the coupling is in one direction only. Movement of solid boundaries was determined in previous work for a deformable solid bolus. Two swallowing simulations are presented with different bolus viscosities in order to demonstrate that SPH can be used to simulate and track the liquid phase of a bolus during swallow. We find that SPH robustly handles moving boundary conditions as well as changes in viscosity. SPH simulations of the bolus are therefore potentially a useful visual aid to understand the effects of solid boundary motion on swallowing.