A model experiment to understand the oral phase of swallowing of Newtonian liquids

In vivo observations and in vitro experiments on the oral phase of swallowing of Newtonian and shear-thinning liquids

“…Consequently, individuals who have poor tongue 355 strength are likely to experience longer transit times than those with normal tongue strength. In addition, in those individuals the oral transit time of the bolus will be more sensitive to its rheology, meaning that overly thickened boluses are more likely to induce potentially hazardous fluid residue and bad swallowing efficiency, as discussed in the introduction and previously observed in 360 vitro (Hayoun et al, 2015).…”

“…This device, shown in Figure 1, is based on a mouth-sized in vitro experiment initially designed by Mackley et al (2013) and later improved by Hayoun et al (2015). Without having the ambition of reproducing faithfully the in vivo process, the objective of this 90 study was to capture two essential features of the mouth and tongue.…”

“…The effect of gravity on 95 the rotating arm is cancelled out by a counterweight. Different driving forces F lead to different pressures applied on the liquid, which can be computed as illustrated in Hayoun et al (2015).…”

“…A significant improvement made to the model experiment in this current study, with respect to the experiment used in Hayoun et al (2015), consists 100 of the possibility of varying the total moment of inertia I tot of the rotating arm, roller and counterweight assembly. To that effect, two radially opposed rods, each carrying an offset mass, can be attached to the rotating arm.…”

“…where I tot is the moment of inertia of the rotating arm, roller, counterweight and (possibly) offset masses assembly, I bolus that of the bolus with respect to the center of rotation and F is the driving force provided by the weight suspended by The theory presented in Hayoun et al (2015) was improved by considering the effect of gravity, represented by the last term in Equation (1). In order to take into account the large range of Reynolds numbers possible in the bolus flow, the dissipation force F d (ρ, η, ω) is now computed from a computational fluid dynamics (CFD) simulation of the flow within the bolus, as described in the Appendix.…”