The Aerodynamics of a Diabolo

Angular Momentum ◽

Flow Pattern ◽

High Spin ◽

Angular Speed ◽

Geometric Shape ◽

Cfd Simulations ◽

Resistive Torque ◽

Diabolo is a popular game in which the object can be spun at up to speeds of 5000 rpm. This high spin velocity gives the diabolo the necessary angular momentum to remain stable. The shape of the diabolo generates an interesting air flow pattern. The viscous air applies a resistive torque on the fast spinning diabolo. Through computational fluid dynamics (CFD) simulations it's shown that the resistive torque has an interesting dependence on the angular speed of the diabolo. Further, the geometric shape of the diabolo affects the dependence of torque on angular speed.

The Effects of the Presence of a Kitchen House on the Wind Flow Surrounding a Low-Rise Building

Energies ◽

10.3390/en13236243 ◽

2020 ◽

Vol 13 (23) ◽

pp. 6243

Author(s):

Siti Noratikah Che Deraman ◽

Saddam Hussein Abo Sabah ◽

Shaharudin Shah Zaini ◽

Taksiah A. Majid ◽

Amin Al-Fakih

Keyword(s):

Fluid Dynamics ◽

Flow Pattern ◽

Air Flow ◽

Flow Characteristics ◽

Wind Flow ◽

Cfd Simulations ◽

The Core ◽

Gap Height

Most Malaysian rural houses are categorized as non-engineered buildings and vulnerable to damage during events such as windstorms due to the fact that these houses lack engineering considerations. These houses are characterized by having an attached kitchen house, and many of these houses were previously damaged by thunderstorms. The current research investigated the air flow characteristics changes surrounding these houses as a result of the presence of the kitchen. The roof pitch, position, gap height, and overhang were investigated using computational fluid dynamics (CFD) simulations. The results showed that the kitchen position at the center resulted in a slight increase in the suction on the ridge of the roof; however, it significantly altered the flow pattern in the windward and leeward directions. The results also showed that the roof overhang, roof pitch, and kitchen position contributed severely to the damage of the rural house. Moreover, the highest suction occurred at the roof ridge when the kitchen was located at the center of the rural house (Cp = −2.28). Therefore, the authors believe that it is more advantageous to have a kitchen connected to the core as it reduces the pressure on the roof of the core during thunderstorm events.

Rapid pivot feeding in pipefish: flow effects on prey and evaluation of simple dynamic modelling via computational fluid dynamics

Journal of The Royal Society Interface ◽

10.1098/rsif.2008.0101 ◽

2008 ◽

Vol 5 (28) ◽

pp. 1291-1301 ◽

Cited By ~ 8

Author(s):

Sam Van Wassenbergh ◽

Peter Aerts

Keyword(s):

Fluid Dynamics ◽

Analytical Model ◽

Dynamic Modelling ◽

Head Rotation ◽

Theoretical Models ◽

Cfd Simulations ◽

Deceleration Phase ◽

Flow Effects

Most theoretical models of unsteady aquatic movement in organisms assume that including steady-state drag force and added mass approximates the hydrodynamic force exerted on an organism's body. However, animals often perform explosively quick movements where high accelerations are realized in a few milliseconds and are followed closely by rapid decelerations. For such highly unsteady movements, the accuracy of this modelling approach may be limited. This type of movement can be found during pivot feeding in pipefish that abruptly rotate their head and snout towards prey. We used computational fluid dynamics (CFD) to validate a simple analytical model of cranial rotation in pipefish. CFD simulations also allowed us to assess prey displacement by head rotation. CFD showed that the analytical model accurately calculates the forces exerted on the pipefish. Although the initial phase of acceleration changes the flow patterns during the subsequent deceleration phase, the accuracy of the analytical model was not reduced during this deceleration phase. Our analysis also showed that prey are left approximately stationary despite the quickly approaching pipefish snout. This suggests that pivot-feeding fish need little or no suction to compensate for the effects of the flow induced by cranial rotation.

Effect of hydraulic and geometric factors upon leakage flow rate in pressurized pipes

RBRH ◽

10.1590/2318-0331.262120210057 ◽

2021 ◽

Vol 26 ◽

Author(s):

Mayara Francisca da Silva ◽

Fábio Veríssimo Gonçalves ◽

Johannes Gérson Janzen

Keyword(s):

Fluid Dynamics ◽

Flow Rate ◽

Leakage Flow ◽

Cfd Simulations ◽

Mean Velocity ◽

Leakage Flow Rate ◽

Geometric Factors ◽

Leakage Area ◽

ABSTRACT Computational Fluid Dynamics (CFD) simulations of a leakage in a pressurized pipe were undertaken to determine the empirical effects of hydraulic and geometric factors on the leakage flow rate. The results showed that pressure, leakage area and leakage form, influenced the leakage flow rate significantly, while pipe thickness and mean velocity did not influence the leakage flow rate. With relation to the interactions, the effect of pressure upon leakage flow rate depends on leakage area, being stronger for great leakage areas; the effects of leakage area and pressure on leakage flow rate is more pronounced for longitudinal leakages than for circular leakages. Finally, our results suggest that the equations that predict leakage flow rate in pressurized pipes may need a revision.

Efficiency analysis of an incompressible-flow ejector using Computational Fluid Dynamics (CFD) simulations and mathematical modeling.

10.11606/d.3.2020.tde-24052021-094502 ◽

2020 ◽

Author(s):

Victor Jorge de Oliveira Marum

Keyword(s):

Mathematical Modeling ◽

Fluid Dynamics ◽

Incompressible Flow ◽

Efficiency Analysis ◽

Cfd Simulations ◽

Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

Fluids ◽

10.3390/fluids3040073 ◽

2018 ◽

Vol 3 (4) ◽

pp. 73 ◽

Cited By ~ 10

Author(s):

Galih Bangga

Keyword(s):

Fluid Dynamics ◽

Flow Separation ◽

Spatial Interpolation ◽

Flow Conditions ◽

Cfd Simulations ◽

Correction Terms ◽

Selection Of ◽

Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

Effects of viscosity on the performance of Hydraulic Power Recovery Turbines (HPRTs) by the means of Computational Fluid Dynamics (CFD) simulations

Energy Procedia ◽

10.1016/j.egypro.2018.08.046 ◽

2018 ◽

Vol 148 ◽

pp. 170-177 ◽

Cited By ~ 5

Author(s):

Mosè Rossi ◽

Gabriele Comodi ◽

Nicola Piacente ◽

Massimiliano Renzi

Keyword(s):

Fluid Dynamics ◽

Cfd Simulations ◽

Hydraulic Power ◽

Power Recovery

Experimental and CFD Modelling: Impact of the Inlet Slug Flow on the Horizontal Gas–Liquid Separator

Energies ◽

10.3390/en12010041 ◽

2018 ◽

Vol 12 (1) ◽

pp. 41

Author(s):

Siong Lee ◽

Thomas Choong ◽

Luqman Abdullah ◽

Mus’ab Abdul Razak ◽

Zhen Ban

Keyword(s):

Fluid Dynamics ◽

Liquid Phase ◽

Flow Pattern ◽

Slug Flow ◽

Cavity Formation ◽

Cfd Modelling ◽

The Impact ◽

Liquid Separator

For a gas-liquid separator sizing, many engineers have neglected the flow pattern of incoming fluids. The impact of inlet slug flow which impeded onto the separator’s liquid phase will cause a separator fails to perform when sloshing happened in the separator. To date, the study on verifying the impact of inlet slug flow in a separator remains limited. In this paper, the impact of inlet momentum and inlet slug flow on the hydrodynamics in a separator for cases without an inlet device were investigated. The experimental and Computational Fluid Dynamics (CFD) results of cavity formation and sloshing occurrence in the separator in this study were compared. A User Defined Function (UDF) was used to describe the inlet slug flow at the separator inlet. Inlet slug flow occurred at inlet momentum from 200 to 1000 Pa, and sloshing occurred in the separator at 1000 Pa. Both experimental and simulated results showed similar phenomena.

Investigation of Influence of Adjustments in Cyclist Arm Position on Aerodynamic Drag Using Computational Fluid Dynamics

Proceedings ◽

10.3390/proceedings2020049159 ◽

2020 ◽

Vol 49 (1) ◽

pp. 159

Author(s):

Knut Erik Teigen Giljarhus ◽

Daniel Årrestad Stave ◽

Luca Oggiano

Keyword(s):

Fluid Dynamics ◽

Aerodynamic Drag ◽

Time Trial ◽

Elbow Extension ◽

Cfd Simulations ◽

Arm Position ◽

Sport Activities ◽

The Face ◽

In professional cycling, even small adjustments in position could mean that valuable seconds are gained over the course of a time-trial race. This study investigates the influence of arm position on the aerodynamic drag of a cyclist. Based on a 3D scanned model of a professional cyclist, 64 alternate positions are generated. The parameters that are investigated are the distance between elbows, elbow extension, and distance between hands. Computational fluid dynamics (CFD) simulations of all positions are performed, and a regression model is built from the results. The results indicate that the optimal posture is achieved for a minimum in all investigated parameters, which means that the hands and elbows should be kept together with hands up towards the face. Furthermore, elbow extension seems to be the most crucial parameter, followed by the distance between elbows, and then by the distance between the hands. The presented methodology can be applied to study other parameters relevant to cycling aerodynamics or be applied to other sport activities as well.