Article
Engineering, Mechanical
C. Garcia-Baena, J. M. Camacho-Sanchez, M. Lorite-Diez, C. Gutierrez-Montes, J. I. Jimenez-Gonzalez
Summary: The aerodynamics of a blunt-based body with rear flexibly-hinged rigid flaps was studied under turbulent flow conditions. Different values of the equivalent torsional stiffness were considered and the effect of the angular deflection of plates on drag and near wake flow was analyzed. The results showed that the plates exhibited an inwards quasi-static, self-adaptive deflection, with smaller mean deformation angles for lower values of reduced velocity. The study also found that reductions in drag coefficients and changes in recirculating bubble size were observed.
JOURNAL OF FLUIDS AND STRUCTURES
(2023)
Article
Mechanics
Athanasios Emmanouil Giannenas, Sylvain Laizet, Georgios Rigas
Summary: A numerical study was conducted to investigate the response of a two-dimensional bluff body wake subjected to harmonic forcing by two rear pitching flaps. The study found that near the resonant regime, the wake intensity and drag increased, while away from the resonant regime, the wake symmetrisation and propulsion mechanisms led to a significant drag reduction.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Civil
Z. X. Qiao, G. Minelli, B. R. Noack, S. Krajnovic, V. Chernoray
Summary: This study investigates the manipulation of a bluff body flow with a yaw angle of 10° using genetic algorithm optimization. The experiment achieved significant drag reduction and increased energy efficiency compared to single frequency control.
JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS
(2021)
Article
Engineering, Civil
Guang Chen, Xi-Feng Liang, Xiao-Bai Li, Dan Zhou, Fue-sang Lien, Jiangbo Wang
Summary: The study using improved delayed detached eddy simulation (IDDES) focused on the aerodynamic performance impact of train platoon configurations. It found that the platoon configuration mainly affects the aerodynamic forces of the tail car of the front train and the head car of the rear train through flow interference.
JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS
(2021)
Article
Physics, Fluids & Plasmas
J. M. Camacho-Sanchez, M. Lorite-Diez, J. I. Jimenez-Gonzalez, O. Cadot, C. Martinez-Bazan
Summary: We conducted an experimental study on turbulent flow around a square-back Ahmed vehicle with different yaw angles to analyze the effectiveness of using rear flexibly hinged parallel plates as a control strategy to reduce drag under changing flow conditions. The results showed that the hinged plates decreased the drag coefficient of the vehicle by approximately 4.4% for flow conditions aligned with the body axis and by nearly 9.1% for cross-flow conditions at a yaw angle of -10 degrees. The hinged flaps were also found to interact with the reflectional-symmetry-breaking modes in the wake of the vehicle.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Mechanics
Zhicheng Wang, Dixia Fan, Xiaomo Jiang, Michael S. Triantafyllou, George Em Karniadakis
Summary: This paper demonstrates how to accelerate the computationally taxing process of deep reinforcement learning for active control of bluff body flows at high Reynolds number using transfer learning. The results show that transfer learning greatly reduces training episodes and improves stability compared to training from scratch. The wake flow at high Reynolds number is analyzed, revealing an asymmetry in the hydrodynamic forces on the two rotating control cylinders for the first time.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Engineering, Mechanical
I. A. Carvalho, G. R. S. Assi
Summary: This paper examines an active mechanism of wake control for a turbulent flow regime of Reynolds number 1000, and compares two different arrangements of rotating rods to control the wake. The results show that the rotation rates inspired by the solution of potential flow around the body are more effective in controlling the wake, eliminating turbulent structures, and reducing the drag and lift fluctuations.
JOURNAL OF FLUIDS AND STRUCTURES
(2022)
Article
Mechanics
Amir Sagharichi, Seyed Sobhan Aleyasin, Mark Francis Tachie
Summary: An experimental study was conducted to investigate the effects of rounded and squared leading edge on the flow characteristics around a slanted-back Ahmed body. The results showed that sharpening the leading edge increases the recirculation region near the body's leading edge. However, it slightly reduces the recirculation region in the wake region. The analysis also revealed that the extent of the region of elevated integral timescale is greater in the squared leading edge case.
Article
Green & Sustainable Science & Technology
Reza Roohi, Masoud Akbari, Ali Karimzadeh, Mohammad Javad Amiri
Summary: This study focuses on the performance of a galloping piezoelectric micro energy harvester (GPEH) designed for MEMS applications. The impact of aspect ratio and mass on the harvested power is examined through simulations, with results showing that higher aspect ratios and appropriate mass can enhance the efficiency of the energy harvester.
Article
Engineering, Multidisciplinary
Tong Liang, Yang Xu, Jiawen Li, Guobiao Cai
Summary: The study demonstrates that under rotational flow conditions, micro riblets of certain dimensions can significantly reduce resistant torque, the drag reduction efficiency depends on rotational Reynolds number and riblet dimensions, and the reduction is achieved by altering the distribution of static pressure and swirl velocity on surfaces as well as tranquilizing near-wall turbulence intensity.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Engineering, Civil
Christopher Brown, David Burton, Timothy Crouch, Mark C. Thompson
Summary: Many previous studies have focused on characterizing Reynolds number effects and skinsuit design for aerodynamic performance improvement, but most of these studies were conducted in wind tunnels with lower turbulence intensities compared to outdoor competitions. In this experimental study, the influence of freestream turbulence on cyclist aerodynamics is investigated. The results show that higher turbulence levels lead to lower aerodynamic drag and affect the flow separation and wake structures. The interaction between turbulence level and skinsuit roughness is also considered for the arms.
JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS
(2023)
Article
Engineering, Mechanical
Zongnan Chen, Chih-Yung Wen
Summary: The experimental study investigates the control performance of different types of plasma actuators on reducing bluff body flow separation, vortex-induced vibration, and wake fluctuation. The results show that the hybrid actuator achieves the best performance by enhancing mixing through improved three-dimensional flow structures on the bluff body surface, reducing drag and lift oscillations.
JOURNAL OF FLUIDS AND STRUCTURES
(2021)
Article
Energy & Fuels
Hesham Ebrahim, Robert Dominy
Summary: It is well established that closely spaced platoons of passenger cars can reduce aerodynamic drag, resulting in energy savings and emissions reduction. While most research has focused on platoons of identical vehicles, the optimal arrangement for pairs of vehicles to maximize drag reduction is crucial.
Article
Engineering, Marine
Sukruth Satheesh, Andreas Spohn, Franck Kerherv, Laurent Cordier
Summary: Experiments conducted in a low-speed water tunnel with circular and square plate models revealed that drag increases rapidly with inclination for small angles, but becomes nearly independent of inclination at high angles. The transition between drag regimes occurs at an inclination of 54 degrees.
Article
Thermodynamics
Yann Haffner, Ruiying Li, Marcello Meldi, Jacques Boree
Summary: Highly resolved computations using Delayed Detached Eddy Simulations (DDES) were conducted to investigate the flow around a canonical car model. The results showed that introducing a perturbing cylinder at different positions around the model can either increase or decrease the drag. The sensitivity of drag to the cylinder position is related to the relative position of flow reattachment after separation. In the drag-optimal case, where the flow reattachment occurs at the same location as the base, the asymmetry of the wake is reduced and the pressure in the wake is globally recovered. The drag reduction is attributed to two flow mechanisms: the inward deviation of the flow induced by the flow reattachment at the trailing edge, acting as an inward-oriented flap, and the forcing of the windward shear layer by the turbulent field along the separated region of the perturbing cylinder.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2022)
Article
Engineering, Aerospace
Mohd Fadhli, Ashraf A. Omar, Waqar Asrar
Article
Engineering, Aerospace
Hani B. Ludin, Ashraf A. Omar, Waqar Asrar
JOURNAL OF AEROSPACE ENGINEERING
(2015)
Letter
Biology
Anwar Ul-Haque, Waqar Asrar, Ashraf A. Omar, Erwin Sulaeman, J. S. Mohamed Ali
JOURNAL OF EXPERIMENTAL BIOLOGY
(2015)
Article
Engineering, Aerospace
Afaq Altaf, Tan Boon Thong, Ashraf A. Omar, Waqar Asrar
Article
Engineering, Multidisciplinary
Anwar U. Haque, Waqar Asrar, Ashraf A. Omar, Erwin Sulaeman
Article
Mechanics
Mohammed Aldheeb, Waqar Asrar, Erwin Sulaeman, Ashraf A. Omar
Article
Thermodynamics
M. Aldheeb, W. Asrar, A. Omar, A. Altaf, E. Sulaeman
JOURNAL OF APPLIED FLUID MECHANICS
(2020)
Article
Engineering, Mechanical
O. Elsayed, A. Omar, A. Jeddi, S. Elhessni, F. Z. Hachimy
Summary: Three different passive flow control techniques were applied to a sport-utility-vehicle (SUV) to reduce drag, including a closed rectangular flap, a perforated roof surface layer, and air guided through side rams. These techniques effectively reduced drag, with the most pronounced reduction reaching 22.67%.
INTERNATIONAL JOURNAL OF AUTOMOTIVE AND MECHANICAL ENGINEERING
(2021)
Article
Engineering, Mechanical
Hachimy Fatima-Zahra, Ashraf Omar, Omer Elsayed, Kenza Bouchaala
Summary: In this study, the aerodynamic drag reduction of a simplified van model was investigated through the installation of a side flap at the rear end. ANSYS-Fluent was used for computational fluid dynamics analysis, with a robust Taguchi test design method applied for optimizing the independent parameters of the side flap design. Validation was done using the Ahmed body model. The study showed that adding a side flap can effectively reduce the aerodynamic drag, with a maximum reduction of 11.50% for total drag coefficient and 11.73% for pressure drag coefficient achieved.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE ENGINEERING
(2023)
Article
Engineering, Aerospace
Anwar ul-Haque, Waqar Asrar, Ashraf Ali Omar, Erwin Sulaeman, J. S. Mohamed Ali
AIRCRAFT ENGINEERING AND AEROSPACE TECHNOLOGY
(2017)
Article
Engineering, Aerospace
Anwar Ul Haque, Waqar Asrar, Asharf Ali Omar, Erwin Suleiman
JOURNAL OF AEROSPACE TECHNOLOGY AND MANAGEMENT
(2016)
Review
Engineering, Aerospace
Mohammed Abdulmalek Aldheeb, Waqar Asrar, Erwin Sulaeman, Ashraf Ali Omar
JOURNAL OF AEROSPACE TECHNOLOGY AND MANAGEMENT
(2016)
Article
Computer Science, Interdisciplinary Applications
Mohd Fadhli, Ashraf Ali Omar, Waqar Asrar
INTERNATIONAL JOURNAL OF COMPUTATIONAL SCIENCE AND ENGINEERING
(2015)
Article
Mechanics
Abdulhafid Elfaghi, Ashraf Ali Omar, Andwaqar Asrar
INTERNATIONAL JOURNAL FOR COMPUTATIONAL METHODS IN ENGINEERING SCIENCE & MECHANICS
(2015)
