Numerical simulation of interaction between organs and food bolus during swallowing and aspiration.

The mechanism of swallowing is still not fully understood, because the process of swallowing is a rapid and complex interaction among several involved organs and the food bolus. In this work, with the aim of studying swallowing and aspiration processes noninvasively and systematically, a computer simulation method for analyzing the involved organs and water (considered as the food bolus) is proposed. The shape and motion of the organs involved in swallowing are modeled in the same way as in our previous study, by using the Hamiltonian moving particle simulation (MPS) method and forced displacements on the basis of motion in a healthy volunteer. The bolus flow is simulated using the explicit MPS method for fluid analysis. The interaction between the organs and the bolus is analyzed using a fluid-structure coupling scheme. To validate the proposed method, the behavior of the simulated bolus flow is compared qualitatively and quantitatively with corresponding medical images. In addition to the healthy motion model, disorder motion models are constructed for reproducing the aspiration phenomenon by computer simulation. The behaviors of the organs and the bolus considered as the food bolus in the healthy and disorder motion models are compared for evaluating the mechanism of aspiration.