Unsteady Aerodynamic Flow Investigation Around a Simplified Square-Back Road Vehicle With Drag Reduction Devices

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Bahram Khalighi ◽  
Kuo-Huey Chen ◽  
G. Iaccarino
Keyword(s):  
Drag Reduction ◽  
Three Dimensional ◽  
Common Element ◽  
Road Vehicle ◽  
Flow Investigation ◽  
Upward Deflection ◽  
Unsteady Rans ◽  
The Common ◽  
Shedding Frequency ◽  
Coanda Jet

The unsteady flow around a simplified road vehicle model with and without drag reduction devices is investigated. The simulations are carried out using the unsteady RANS in conjunction with the v2-f turbulence model. The corresponding experiments are performed in a small wind tunnel which includes pressure and velocity fields measurements. The devices are add-on geometry parts (a box with a cavity and, boat-tail without a cavity) which are attached to the back of the square-back model to improve the pressure recovery and reduce the flow unsteadiness. The results show that the recirculation regions at the base are shortened and weakened and the base pressure is significantly increased by the devices which lead to lower drag coefficients (up to 30% reduction in drag). Also, the results indicate a reduction of the turbulence intensities in the wake as well as a rapid upward deflection of the underbody flow with the devices in place. A reduction of the unsteadiness is the common element of the devices studied. The baseline configuration (square-back) exhibits strong three-dimensional flapping of the wake. The main shedding frequency captured agrees well with the available experimental data. Comparisons with the measurements show that the simulations agree reasonably well with the experiments in terms of drag and the flow structures. Finally, a blowing system (Coanda jet) is investigated numerically. In this case a drag reduction of up to 50% is realized.

Study of Drag Reduction Devices for a Square Back Vehicle Configuration Using RANS CFD Simulations

2012 ◽  
Author(s):  
Bahram Khalighi ◽  
Kuo-Huey Chen ◽  
Gianluca Iaccarino
Keyword(s):  
Drag Reduction ◽  
Three Dimensional ◽  
Common Element ◽  
Flow Structures ◽  
Vehicle Model ◽  
Cfd Simulations ◽  
Upward Deflection ◽  
Unsteady Rans ◽  
The Common ◽  
Shedding Frequency

The aerodynamic flow around a simplified road vehicle model with and without drag reduction devices is investigated. The simulations are carried out using the unsteady RANS in conjunction with the ν2-f turbulence model. The corresponding experiments are performed in a small wind tunnel which includes pressure and velocity fields measurements. The devices are add-on geometry parts (a box with a cavity and, boat-tail without a cavity) which are attached to the back of the square-back model to improve the pressure recovery and reduce the flow unsteadiness. The results show that the recirculation regions at the base are shortened and weakened and the base pressure is significantly increased by the devices which lead to lower drag coefficients (up to 30% reduction in drag). Also, the results indicate a reduction of the turbulence intensities in the wake as well as a rapid upward deflection of the underbody flow with the devices in place. A suppression or damping of the unsteadiness is the common element of the devices studied. The baseline configuration (square-back) exhibits strong three-dimensional flapping of the wake. The main shedding frequency captured agrees well with the available experimental data. Comparisons with the measurements show that the simulations agree reasonably well with the experiments in terms of drag and the flow structures.

Drag reduction and wear resistance mechanisms of a bionic shovel by discrete element method simulation

SIMULATION ◽  
2018 ◽  
Vol 95 (3) ◽  
pp. 231-239 ◽  
Author(s):  
Rui Zhang ◽  
Dianlei Han ◽  
Yuan He ◽  
Haijin Wan ◽  
Songsong Ma ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Drag Reduction ◽  
High Speed ◽  
Three Dimensional ◽  
Discrete Element ◽  
Resistance Mechanisms ◽  
Fatigue Wear ◽  
Soil Particles ◽  
The Common ◽  
Element Method

The ostrich has a steady and enduring high-speed running ability. Toenails are one key part of ostrich feet and their unique morphology is crucial in insertion into sand and for traction provision. In this study, information of bionic curves was extracted through studying the toenail structure and morphology, and three-dimensional reconstruction of toenails by reverse engineering. Based on the principle of bionic engineering, a bionic shovel was designed by optimizing the traditional shovel. A shovel–soil interaction mechanical model was established via the discrete element method. The insertion into soil processes of the bionic shovel and the common plate were simulated. The dynamic mesoscopic mechanical behaviors of soil particles around the shovel surface, the contact force field, and the velocity field, as well as the forces acting on the shovel surface were analyzed. The bionic shovel outperformed the common plate in insertion. The main reason for drag reduction in the bionic shovel was the inner concave bending surface, along which the soil particles climbed, and the particle movement trend was consistent. Simulations showed stress concentrated at the tip of the shovel, which facilitated the production of fatigue wear. Therefore, the tip needs to be considered firstly during bionic shovel design in the future.

Diagnostic System of Gravitational Solid Flow Based on Weight and Accelerometer Signal Analysis Using Wireless Data Transmission Technology

2012 ◽  
Vol 17 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Zbigniew Chaniecki ◽  
Krzysztof Grudzień ◽  
Tomasz Jaworski ◽  
Grzegorz Rybak ◽  
Andrzej Romanowski ◽  
...  
Keyword(s):  
Signal Analysis ◽  
Scale Up ◽  
Three Dimensional ◽  
Diagnostic System ◽  
Wireless Data ◽  
Stick Slip ◽  
Wireless Data Transmission ◽  
Accelerometer Signal ◽  
Flow Investigation ◽  
Material Information

Abstract The paper presents results of the scale-up silo flow investigation in based on accelerometer signal analysis and Wi-Fi transmission, performed in distributed laboratory environment. Prepared, by the authors, a set of 8 accelerometers allows to measure a three-dimensional acceleration vector. The accelerometers were located outside silo, on its perimeter. The accelerometers signal changes allowed to analyze dynamic behavior of solid (vibrations/pulsations) at silo wall during discharging process. These dynamic effects are caused by stick-slip friction between the wall and the granular material. Information about the material pulsations and vibrations is crucial for monitoring the interaction between silo construction and particle during flow. Additionally such spatial position of accelerometers sensor allowed to collect information about nonsymmetrical flow inside silo.

Iterative algorithm for a split equilibrium problem and fixed problem for finite asymptotically nonexpansive mappings in Hlbert space

Filomat ◽  
2017 ◽  
Vol 31 (5) ◽  
pp. 1423-1434 ◽  
Author(s):  
Sheng Wang ◽  
Min Chen
Keyword(s):  
Equilibrium Problem ◽  
Iterative Algorithm ◽  
Nonexpansive Mappings ◽  
Common Element ◽  
Fixed Point Set ◽  
Split Equilibrium Problem ◽  
Asymptotically Nonexpansive Mappings ◽  
Asymptotically Nonexpansive ◽  
Point Set ◽  
The Common

In this paper, we propose an iterative algorithm for finding the common element of solution set of a split equilibrium problem and common fixed point set of a finite family of asymptotically nonexpansive mappings in Hilbert space. The strong convergence of this algorithm is proved.

Manipulation of three-dimensional asymmetries of a turbulent wake for drag reduction

2021 ◽  
Vol 912 ◽  
Author(s):  
Yann Haffner ◽  
Thomas Castelain ◽  
Jacques Borée ◽  
Andreas Spohn
Keyword(s):  
Drag Reduction ◽  
Three Dimensional ◽  
Turbulent Wake

Abstract

Synthetic Strategies to Access Heteroatomic Spirocentres Embedded in Natural Products

Synthesis ◽  
2021 ◽  
Author(s):  
Michael P. Badart ◽  
Bill C. Hawkins
Keyword(s):  
Natural Products ◽  
Heterocyclic Compound ◽  
Chemical Space ◽  
Three Dimensional ◽  
Coupling Reactions ◽  
Conjugate Additions ◽  
Biological Targets ◽  
Compound Libraries ◽  
The Common ◽  
Significant Attention

AbstractThe spirocyclic motif is abundant in natural products and provides an ideal three-dimensional template to interact with biological targets. With significant attention historically expended on the synthesis of flat-heterocyclic compound libraries, methods to access the less-explored three-dimensional medicinal-chemical space will continue to increase in demand. Herein, we highlight by reaction class the common strategies used to construct the spirocyclic centres embedded in a series of well-studied natural products.1 Introduction2 Cycloadditions3 Palladium-Catalysed Coupling Reactions4 Conjugate Additions5 Imines, Aminals, and Hemiaminal Ethers6 Mannich-Type Reactions7 Oxidative Dearomatisation8 Alkylation9 Organometallic Additions10 Conclusions

scholarly journals Crystal structure of a new monoclinic polymorph ofN-(4-methylphenyl)-3-nitropyridin-2-amine

2014 ◽  
Vol 70 (8) ◽  
pp. 58-61
Author(s):  
Aina Mardia Akhmad Aznan ◽  
Zanariah Abdullah ◽  
Vannajan Sanghiran Lee ◽  
Edward R. T. Tiekink
Keyword(s):  
Three Dimensional ◽  
Basis Set ◽  
Dihedral Angles ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
Common Features ◽  
Compound C ◽  
B3lyp Level ◽  
The Common ◽  
Independent Molecules

The title compound, C12H11N3O2, is a second monoclinic polymorph (P21, withZ′ = 4) of the previously reported monoclinic (P21/c, withZ′ = 2) form [Akhmad Aznanet al.(2010).Acta Cryst.E66, o2400]. Four independent molecules comprise the asymmetric unit, which have the common features of asyndisposition of the pyridine N atom and the toluene ring, and an intramolecular amine–nitro N—H...O hydrogen bond. The differences between molecules relate to the dihedral angles between the rings which range from 2.92 (19) to 26.24 (19)°. The geometry-optimized structure [B3LYP level of theory and 6–311 g+(d,p) basis set] has the same features except that the entire molecule is planar. In the crystal, the three-dimensional architecture is consolidated by a combination of C—H...O, C—H...π, nitro-N—O...π and π–π interactions [inter-centroid distances = 3.649 (2)–3.916 (2) Å].

The crystal structure of myoglobin. VI. Seal myoglobin

1960 ◽  
Vol 258 (1293) ◽  
pp. 181-201 ◽  
Keyword(s):  
Tertiary Structure ◽  
Heavy Atom ◽  
Three Dimensional ◽  
Sperm Whale ◽  
Fourier Synthesis ◽  
Heavy Atoms ◽  
Isomorphous Replacement ◽  
Unit Cells ◽  
The Common ◽  
Sperm Whale Myoglobin

Myoglobin from the common seal ( Phoca vitulina ) when crystallized from ammonium sulphate forms monoclinic crystals with space group the unit cell, a = 57·9Å, b = 29·6Å, c = 106·4Å, β = 102°15', contains four molecules. The method of isomorphous replacement has been used in an investigation of the centrosymmetric b -axis projection in which it has been possible to determine signs for nearly all the h0l reflexions having spacings greater than 4Å. Three independent heavy-atom derivatives were employed and the signs so determined have been used to compute a map of the electron density projected on the (010) plane. This projection has been interpreted in terms of the molecule of sperm-whale myoglobin, as deduced by Bodo, Dintzis, Kendrew & Wyckoff (1959) from a three-dimensional Fourier synthesis to 6Å resolution. The results of the interpretation show that the two myoglobin molecules are very similar in form (tertiary structure) in spite of the differences in their amino-acid composition. The relative orientation of the two unit cells with respect to the myoglobin molecule is given and a comparison is made of the positions of the heavy atoms in each molecule.

Mechanism Design and Kinematics Simulation of Massage Mechanical Arm

2011 ◽  
Vol 101-102 ◽  
pp. 279-282 ◽  
Author(s):  
Jun Xie ◽  
Jun Zhang ◽  
Jie Li
Keyword(s):  
Mechanism Design ◽  
Three Dimensional ◽  
Forward Kinematics ◽  
Kinematics Analysis ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Kinematics Model ◽  
Kinematics Simulation ◽  
The Common ◽  
Executive Mechanism

Based on the characteristics and the common massage manipulations of Chinese medical massage, a practical series mechanical arm was presented to act the manipulations with the parallel executive mechanism. Forward kinematics was solved by the Denavit-Hartenberg transformation after the kinematics model of the arm was established. And the three-dimensional model of the arm was created by Pro/E and was imported into ADAMS for the kinematics analysis. The results indicated that the common massage manipulations could be simulated by the arm correctly and flexibly, and it verified the accuracy of the mechanism design of the arm.

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