Velocity field and turbulence structure of the meandering flow produced by alternating deflectors.

Meandering flow can be formed during the advance of natural rivers by the scouring of river banks. However, this phenomenon is not common in artificial cement channels. This study used experimental scouring terrain data for a numerical simulation to study the meandering flow pattern formed between double alternating deflectors in a straight channel.

A study on the hydrodynamic performance of manta ray biomimetic glider under unconstrained six-DOF motion.

A manta ray biomimetic glider is designed and studied with both laboratory experiments and numerical simulations with a new dynamic update method called the motion-based zonal mesh update method (MBZMU method) to reveal its hydrodynamic performance. Regarding the experimental study, an ejection gliding experiment is conducted for qualitative verification, and a hydrostatic free-fall experiment is conducted to quantitatively verify the reliability of the corresponding numerical simulation. Regarding the numerical simulation, to reduce the trend of nose-up movement and to obtain a long lasting and stable gliding motion, a series of cases with the center of mass offset forward by different distances and different initial angles of attack have been calculated.

Gliding locomotion of manta rays, killer whales and swordfish near the water surface.

The hydrodynamic performance of the locomotive near the water surface is impacted by its geometrical shape. For marine animals, their geometrical shape is naturally selective; thus, investigating gliding locomotion of marine animal under the water surface may be able to elucidate the influence of the geometrical shape. We investigate three marine animals with specific geometries: the killer whale is fusiform shaped; the manta ray is flat and broad-winged; and the swordfish is best streamlined.

Hydrodynamic analysis of human swimming based on VOF method.

A 3-D numerical model, based on the Navier-Strokes equations and the RNG k-ε turbulence closure, for studying hydrodynamic drag on a swimmer with wave-making resistance taken into account is established. The volume of fluid method is employed to capture the undulation of the free surface. The simulation strategy is evaluated by comparison of the computed results with experimental data.

Computational synovial dynamics of a normal temporomandibular joint during jaw opening.

Background/purpose: Synovial fluid in the temporomandibular joint (TMJ) acts as a lubricant and shock absorber, facilitating smooth jaw movements by reducing friction and cushioning the articular cartilage and other tissues in the TMJ. This study investigated the flow pattern of synovial fluid in the articular cavity during jaw opening.

Methods: The upper TMJ compartment in a healthy individual was studied by computed tomography arthrography, and the intra-articular pressures were measured during jaw opening.

CO2 absorption/emission and aerodynamic effects of trees on the concentrations in a street canyon in Guangzhou, China.

In this paper, the effects of trees on CO2 concentrations in a street canyon in Guangzhou, China are examined by Computational Fluid Dynamics (CFD) simulations of the concentration distribution, taking into account both the CO2 absorption/emission and aerodynamic effects of trees. Simulation results show that, under a 2 m/s southerly prevailing wind condition, CO2 absorption by trees will reduce the CO2 concentration by around 2.5% in the daytime and at the same time the trees' resistance will increase the difference of CO2 concentrations in the street and at the inflow by 43%.

[Numerical simulation study on effects of ambient temperature on airflow in the nasal cavity].

Objective: To study the aerodynamics of the normal human nasal cavity under different ambient temperatures.

Methods: Based on CT scanning, a model of a healthy adult's nasal cavity was established using computational fluid dynamics software from Fluent. Airflow in this model was simulated and calculated at ambient temperatures of 0 °C, 24 °C, and 37 °C during periodic breathing.

Three-dimensional double-diffusive Marangoni convection in a cubic cavity with horizontal temperature and concentration gradients.

Three-dimensional double-diffusive Marangoni convection in a cubic cavity is studied in the present paper. Both the temperature and solute concentration gradients are applied horizontally. Direct numerical simulations are carried out for surface-tension Reynolds number 10≤Re≤500, surface-tension ratio -2≤R(σ)≤1, and Lewis number 1 View Article and Find Full Text PDF

[A comparative study on numerical simulation of the normal nasal airflow during periodic breathing and steady-state breathing].

Objective: To compare the characteristics of normal nasal airflow during periodic breathing and steady-state breathing.

Methods: Fluent software was used to simulate the nasal cavity and paranasal sinus structures following CT scanning of a normal adult subject. Air flow velocity, pressure, distribution and streamlines were calculated and compared during periodic breathing and steady-state breathing.

[Effect of endoscopic sinus surgery on airflow of the nasal cavity and paranasal sinuses: a computational fluid dynamics study.].

Objective: To study the airflow velocity, trace, distribution, pressure, as well as the airflow exchange between the nasal cavity and paranasal sinuses in a computer simulation of nasal cavity pre and post virtual endoscopic sinus surgery (ESS).

Methods: Computational fluid dynamics (CFD) technique was applied to construct an anatomically and proportionally accurate three-dimensional nasal model based on a healthy adult woman's nasal CT scans. A virtual ESS intervention was performed numerically on the normal nasal model using Fluent 6.

[Influence of uncinate process on aerodynamic characteristics of nasal cavity and maxillary sinus].

Objective: This study aimed to investigate the influence of uncinate process on air flow velocity, trace, distribution, air pressure, as well as the air flow exchange of nasal cavity and paranasal sinuses.

Methods: Fluent software was used to simulate two nasal cavity and paranasal sinus structures following CT scanning, one had normal nasal cavity, the another had the nasal cavity with uncinate process removed. Air flow velocity, pressure, distribution and trace lines were calculated and compared by Navier-Stokes equation and numerically visualized between two models.

Computational fluid dynamics simulation of airflow in the normal nasal cavity and paranasal sinuses.

Background: This study aimed to investigate airflow velocity, trace, distribution, and air pressure, as well as the airflow exchange between the nasal cavity and paranasal sinus in a normal subject using computational fluid dynamics.

Methods: Fluent software is used to simulate nasal cavity and paranasal sinus structure after CT scanning of a normal adult subject. Airflow velocity, pressure, distribution, and trace lines were calculated by Navier-Stokes equation and numerically visualized.