Analysis of Velopharyngeal Functions Using Computational Fluid Dynamics Simulations

2019 ◽  
Vol 128 (8) ◽  
pp. 742-748 ◽  
Author(s):  
Hanyao Huang ◽  
Xu Cheng ◽  
Yang Wang ◽  
Dantong Huang ◽  
Yuhao Wei ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Computational Fluid Dynamic Simulation ◽  
Dynamic Features ◽  
Upper Airways ◽  
Dynamic Simulations ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Objectives: Competent velopharyngeal (VP) function is the basis for normal speech. Understanding how VP structure influences the airflow during speech details is essential to the surgical improvement of pharyngoplasty. In this study, we aimed to illuminate the airflow features corresponding to various VP closure states using computed dynamic simulations. Methods: Three-dimensional models of the upper airways were established based on computed tomography of 8 volunteers. The velopharyngeal port was simulated by a cylinder. Computational fluid dynamics simulations were applied to illustrate the correlation between the VP port size and the airflow parameters, including the flow velocity, pressure in the velopharyngeal port, as well as the pressure in oral and nasal cavity. Results: The airflow dynamics at the velopharynx were maintained in the same velopharyngeal pattern as the area of the velopharyngeal port increased from 0 to 25 mm2. A total of 5 airflow patterns with distinct features were captured, corresponding to adequate closure, adequate/borderline closure (Class I and II), borderline/inadequate closure, and inadequate closure. The maximal orifice area that could be tolerated for adequate VP closure was determined to be 2.01 mm2. Conclusion: Different VP functions are of characteristic airflow dynamic features. Computational fluid dynamic simulation is of application potential in individualized VP surgery planning.

Stent-Assisted Coil Embolization and Computational Fluid Dynamics Simulations of Bilateral Vertebral Artery Dissecting Aneurysms Presenting With Subarachnoid Hemorrhage

Neurosurgery ◽  
2012 ◽  
Vol 71 (6) ◽  
pp. E1192-E1201 ◽  
Author(s):  
Kenichi Kono ◽  
Aki Shintani ◽  
Takeshi Fujimoto ◽  
Tomoaki Terada
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Subarachnoid Hemorrhage ◽  
Vertebral Artery ◽  
Coil Embolization ◽  
Fluid Dynamic ◽  
Single Session ◽  
Dynamic Simulations ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

ABSTRACT BACKGROUND AND IMPORTANCE: A vertebral artery dissecting aneurysm (VADA) is a relatively rare cause of subarachnoid hemorrhage. Bilateral VADAs are even rarer, and management strategies are controversial. We report a case of bilateral VADAs presenting with subarachnoid hemorrhage. We treated the patient by stent-assisted coil embolization of both aneurysms at a single session on the basis of results of preoperative computational fluid dynamic simulations. CLINICAL PRESENTATION: A 48-year-old man presented with subarachnoid hemorrhage resulting from bilateral VADAs. We treated the patient by stent-assisted coil embolization of both aneurysms at a single session. Before the treatment, we performed computational fluid dynamics simulations to predict the ruptured side. We also estimated the increase in wall shear stress on an aneurysm in case of trapping of another aneurysm, which might cause enlargement and rupture of the aneurysm. The treatment was performed successfully. The patient remains neurologically intact at 14 months from the onset. CONCLUSION: Stent-assisted coil embolization of subarachnoid hemorrhage with bilateral VADAs for both sides is a reasonable treatment because it prevents rebleeding and preserves bilateral vertebral arteries without increasing hemodynamic stress. To the best of our knowledge, this is the first report to describe this type of treatment for bilateral VADAs with subarachnoid hemorrhage. Computational fluid dynamics simulations may be useful for developing treatment strategies for aneurysms.

Three-Dimensional, Two-Phase Computational Fluid Dynamics Simulations of Alkaline Diaphragm Water Electrolysis Devices

2020 ◽  
Vol MA2020-02 (38) ◽  
pp. 2495-2495
Author(s):  
Joseph Steven Lopata ◽  
Sanggyu Kang ◽  
Hyun-Seok Cho ◽  
Chang Hee Kim ◽  
Sirivatch Shimpalee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Water Electrolysis ◽  
Two Phase ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

scholarly journals Optimization and experimental verification of the vibro-impact capsule system in fluid pipeline

2018 ◽  
Vol 233 (3) ◽  
pp. 880-894 ◽  
Author(s):  
Yao Yan ◽  
Yang Liu ◽  
Haibo Jiang ◽  
Zhike Peng ◽  
Alasdair Crawford ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Impact Oscillator ◽  
Pipeline Inspection ◽  
Prototype Development ◽  
Fluid Resistance ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Dynamics Analyses

This paper studies the prototype development of the vibro-impact capsule system aiming for autonomous mobile sensing for pipeline inspection. Self-propelled progression of the system is obtained by employing a vibro-impact oscillator encapsuled in the capsule without the requirement of any external mechanisms, such as wheels, arms, or legs. A dummy capsule prototype is designed, and the best geometric parameters, capsule and cap arc lengths, for minimizing fluid resistance forces are obtained through two-dimensional and three-dimensional computational fluid dynamics analyses, which are confirmed by wind tunnel tests. In order to verify the concept of self-propulsion, both original and optimized capsule prototypes are tested in a fluid pipe. Experimental results are compared with computational fluid dynamics simulations to confirm the efficacy of the vibro-impact self-propelled driving.

Scaled Room Three-Dimensional Computational Fluid Dynamics Simulations

2002 ◽  
Author(s):  
Steven P. O’Halloran ◽  
Mohammad H. Hosni ◽  
B. Terry Beck ◽  
Thomas P. Gielda
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Working Fluid ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Dynamics Simulations

Computational fluid dynamics (CFD) simulations were used to predict three-dimensional flow within a one-tenth-scale room. The dimensions of the scaled room were 732 × 488 × 274 mm (28.8 × 19.2 × 10.8 in.) and symmetry was utilized so that only half of the room was modeled. Corresponding measurements were made under isothermal conditions and water was used as the working fluid instead of air. The commercially available software Fluent was used to perform the simulations. Two turbulence models were used: the renormalization group (RNG) k-ε model and the Reynolds-stress model. The CFD setup is presented in this paper, along with the velocity and turbulent kinetic energy results. The simulation results are compared to previously obtained three-dimensional particle image velocimetry (PIV) measurements made within the same scaled room under similar conditions.

Computational Fluid Dynamics Simulations in Flow Past Arrays of Finite Plate: Marine Current Energy Harvesting Applications

2017 ◽  
Author(s):  
Bashar Attiya ◽  
I-Han Liu ◽  
Cosan Daskiran ◽  
Jacob Riglin ◽  
Alparslan Oztekin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Three Dimensional ◽  
Mean Value ◽  
Wake Flow ◽  
Corner Angle ◽  
Drag Forces ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Computational fluid dynamics simulations have been conducted for flows past two finite tandem plates at Reynolds number of 50,000. Large Eddy Simulations (LES) were employed in two and three-dimensional geometries to study the interference between tandem plate pair. In order to study the effects of plate corner angle on the flow field and drag forces, two different plate end corners, 90° and a sharp 45° corner angle, were also investigated. The switching from 90° to 45° corners complicate the flow pattern, increase the mean value of drag force and the fluctuations of the drag on the plate. As vortices shed from the upstream plate and reached close proximity to the face of the downstream plate, the vortex cores deformed highly. This behavior reduces the drag coefficient in the downstream plate. Drag coefficient was higher in the 45° case, for both the up and downstream plates by 5% and 10% respectively. Drag coefficient of downstream is recovered almost fully in the 45° case with just 3% difference from the upstream compared to 7% difference in 90° case. Lagrangian Coherent structures were identified and presented in a two-dimensional geometry. This gave a better understanding of the wake flow structure and their influence on the hydrodynamic loading on plates. Contours of vorticity fields and iso-surfaces of Q-criterion, and pressure distribution around the plates were also presented and discussed.

scholarly journals Inflow-rotor interaction in Tesla disc turbines: Effects of discrete inflows, finite disc thickness, and radial clearance on the fluid dynamics and performance of the turbine

2018 ◽  
Vol 232 (8) ◽  
pp. 971-991 ◽  
Author(s):  
Sayantan Sengupta ◽  
Abhijit Guha
Keyword(s):  
Fluid Dynamics ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Radial Clearance ◽  
Dynamic Simulations ◽  
Partial Admission ◽  
Inflow Condition ◽  
And Performance ◽  
Dynamics Simulations ◽  
Optimum Formula

The article establishes the physics of the complex interaction of discrete multiple inflows with the stationary shroud and the rotating channel of a Tesla disc turbine. Using a large number (150) of separate, fully three-dimensional computational fluid dynamic simulations, we demonstrate the (sometimes dramatic) role of four important input parameters, namely the number of nozzles ([Formula: see text]), rotational speed of the discs (Ω), radial clearance between the rotor and the shroud ([Formula: see text]), and disc thickness ( dt), in the fluid dynamics and performance of a Tesla turbine. An increase in [Formula: see text] or [Formula: see text] assists in the attainment of axisymmetric condition at rotor inlet. Ω influences significantly the distribution of radial velocity including the fundamental shape of its z-profile (parabolic, flat or W-shaped). The paper demonstrates the existence of an optimum [Formula: see text] for which the efficiency of the rotor (η) is maximized. Present computational fluid dynamics simulations for many combinations of [Formula: see text] and Ω establish that the η versus Ω curves, for each fixed value of [Formula: see text], are of the shape of an inverted bucket. With increasing [Formula: see text], the operable range of Ω decreases, the buckets become more peaky and the maximum possible η increases substantially (by a factor of 2 in the example calculation shown). The present systematic work thus demonstrates quantitatively, for the first time, that an axisymmetric rotor inflow condition represents the best possible design for the rotor. It is further shown that, as the disc thickness is increased, the efficiency may decrease substantially (even dramatically) and its maxima occur at lower rotational speeds. Chamfering of the disc edge or partial admission decreases the turbine efficiency. Thus, small disc thickness, flat disc edge, full nozzle opening, optimum radial clearance, and inlet condition as close to axisymmetry as is possible are recommended for the design of an efficient Tesla disc turbine.

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