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The Montgomery T-tube is used as a combined tracheal stent and airway after laryngotracheoplasty, to keep the lumen open and prevent mucosal laceration from scarring. It is valuable in the management of upper and mid-tracheal lesions, while invaluable in long and multisegmental stenting lesions. Numerical simulations based on real-patient-tracheal geometry, experimental tissue characterization, and previous numerical estimation of the physiological swallowing force are performed to estimate the consequences of Montgomery T-tube implantation on swallowing and assisted ventilation: structural analysis of swallowing is performed to evaluate patient swallowing capacity, and computational fluid dynamics simulation is carried out to analyze related mechanical ventilation. With an inserted Montgomery T-tube, vertical displacement (Z-axis) reaches 8.01 mm, whereas in theY-axis, it reaches 6.63 mm. The maximal principal stress obtained during swallowing was 1.6 MPa surrounding the hole and in the upper contact with the tracheal wall. Fluid flow simulation of the mechanical ventilation revealed positive pressure for both inhalation and exhalation, being higher for inspiration. The muscular deflections, considerable during normal breathing, are nonphysiological, and this aspect results in a constant overload of the tracheal muscle. During swallowing, the trachea ascends producing a nonhomogeneous elongation. This movement can be compromised when prosthesis is inserted, which explains the high incidence of glottis close inefficiency. Fluid simulations showed that nonphysiological pressure is established inside the trachea due to mechanical ventilation. This may lead to an overload of the tracheal muscle, explaining several related problems as muscle thinning or decrease in contractile function. [ABSTRACT FROM AUTHOR]

Abstract: Hydroelasticity is a phenomenon occurring during the interaction between water and a deformable structure. Structural deformations can modify the fluid motion, introducing difficulties in the calculation of the impact-induced stresses. Predicting the structural deformations and stresses during the water entry of flexible structures is a major challenge and suitable computer-aided design tools are currently being developed and validated. This work investigates the water impact of deformable wedges. Experimental and numerical results on the parameters affecting hydroelasticity are evaluated for flexible plates with different boundary conditions. The occurrence of hydroelastic effects is shown to depend on the ratio between the natural frequency of the structure and the characteristic wetting time. The influence of the fluid–structure interactions is investigated by numerical simulations. The conditions for which fluid–structure interactions are significant and must be accounted for in the analysis are identified, while outside this range the structure can be modeled as a rigid body. Pressure at the fluid–structure interface is found not to be influenced by the structural deformation, unless fluid detaches from the structure due to cavitation or ventilation. [Copyright &y& Elsevier]

Abstract: We model the interaction of one-dimensional moving structures with a surrounding three-dimensional fluid, physically close to a Newtonian liquid. The interaction is the adherence of the fluid to the immersed structures, which drag it while moving as rigid bodies. To get solutions of the dynamical problem, we need a model of viscous fluid slightly more general than the Newtonian one, in which the Cauchy stress tensor depends upon higher-order derivatives of the velocity field. Assuming reasonable hypotheses on the motion of the one-dimensional rigid bodies, existence and uniqueness of the solution for the dynamical problem can be proved. [ABSTRACT FROM AUTHOR]