Index-matched measurements of the effect of cartilaginous rings on tracheobronchial flow

Evans, Humberto Bocanegra; Castillo, Luciano

doi:10.1016/j.jbiomech.2016.03.043

Cited by 8 publications

(7 citation statements)

References 24 publications

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“…The effect of the rings reduces the maximum upstream velocity at the separation region by 38%. Similar results of recirculation reduction have also been reported in the separation region at the bifurcation from the trachea to the bronchi [ 6 , 27 ].…”

Section: Resultssupporting

confidence: 86%

“…The smooth model fluctuations stay constant along the model, contrary to the ‘ringed’ model, where the turbulence increases. This occur because the rings are generating perturbations to the flow near the wall, as was also reported in the tracheobronchial flow study [ 6 ]. Finally, as observed in Fig.…”

Section: Resultsmentioning

confidence: 60%

“…Both models have a circular cross-sectional area and an axisymmetric contraction of 70% at the middle of the model. Such contraction allows to observe the effect of tracheal stenosis as well as observe the effect on flow separation, which previous studies have demonstrated to be affected by the rings [ 6 , 27 ]. The 70% area reduction was selected in the hope of understanding why the diagnosis of trachea stenosis below 75% area reduction remains a challenge [ 35 ].…”

Section: Methodsmentioning

confidence: 99%

“…Even though the trachea and main bronchi have undulated walls as a result of the cartilaginous rings [ 26 , 33 ], most research in respiratory fluid dynamics omits these features under the assumption that their effect is negligible. Nevertheless, existing research points to the importance of these small protrusions in both flow structure and aerosol deposition [ 6 , 27 , 33 ]. It is well established that surface roughness can have significant impact on wall-bounded flows [ 16 ], particularly when an adverse pressure gradient (APG), for example, an expansion in the cross-sectional area, is present [ 30 ].…”

Section: Introductionmentioning

confidence: 99%

“…The few studies that have evaluated the effects introduced by cartilaginous rings have found increased particle deposition [ 33 , 44 ], increased shear over the ring surface [ 14 , 39 ], reduced flow separation in the bifurcation [ 6 ], flow recirculation in the ring cavity [ 27 ], and flow asymmetry into the lungs [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

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Effect of cartilaginous rings in tracheal flow with stenosis

et al. 2023

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Background In respiratory fluid dynamics research, it is typically assumed that the wall of the trachea is smooth. However, the trachea is structurally supported by a series of cartilaginous rings that create undulations on the wall surface, which introduce perturbations into the flow. Even though many studies use realistic Computer Tomography (CT) scan data to capture the complex geometry of the respiratory system, its limited spatial resolution does not resolve small features, including those introduced by the cartilaginous rings. Results Here we present an experimental comparison of two simplified trachea models with Grade II stenosis (70% blockage), one with smooth walls and second with cartilaginous rings. The use a unique refractive index-matching method provides unprecedented optical access and allowed us to perform non-intrusive velocity field measurements close to the wall (e.g., Particle Image Velocimetry (PIV)). Measurements were performed in a flow regime comparable to a resting breathing state (Reynolds number ReD = 3350). The cartilaginous rings induce velocity fluctuations in the downstream flow, enhancing the near-wall transport of momentum flux and thus reducing flow separation in the downstream flow. The maximum upstream velocity in the recirculation region is reduced by 38%, resulting in a much weaker recirculation zone— a direct consequence of the cartilaginous rings. Conclusions These results highlight the importance of the cartilaginous rings in respiratory flow studies and the mechanism to reduce flow separation in trachea stenosis.

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 60%