Almost all the insects and birds fly at very low Reynolds numbers. Therefore, to design micro air vehicles (MAVs), a study of airfoils and wings at low Reynolds numbers is essential. Unsteady flow behavior at low Reynolds numbers can vary for different airfoils depending on their camber, maximum thickness, or maximum camber position. Numerical simulations of cambered airfoils (NACA 1412, NACA 2412, NACA 3412, NACA 4412) at Re = 1000 are conducted in the current study to understand the camber effect on the unsteady aerodynamic behavior at a low Reynolds number. The numerical simulations are performed at angles of attack ranging from 0° to 10° with an increment of 1°. A domain with a C-type shape for upstream flow and a rectangular shape for downstream flow is prepared for meshing. Meshes are generated using both a structured grid in the outer region and an unstructured grid in the inner region. Thick boundary layers are implemented around airfoils as at low Reynolds numbers boundary layer gets thicker. The aerodynamic coefficients, pressure distributions, flow separations, and wake flow fields are analyzed from the simulations in detail in the two-dimensional domain. The airfoil producing the highest lift is then simulated in the three-dimensional domain to compare the data with the 2D simulation. In each chapter, the effects of camber are discussed with results.


Inertial redirection of thrust forces for flight stabilization
Demir, Alican; Ankaralı, Mustafa Mert; Dhyr, Jonathan; Morgansen, Kristi; Daniel, Thomas; Cowan, Noah (null, 2012-07-01)
Insects are highly maneuverable fliers. Naturally, engineers have focused much of their efforts on understanding the role of insect wing design and actuation for maneuvering and control of bio-inspired micro air vehicles. However, many insects exhibit strong visually mediated abdominal reflexes. The hawkmoth, Manduca sexta, has a particularly large abdomen, and recent evidence suggests that these visuo-abdominal reflexes are used to inertially redirect thrust forces for control. In a biologically inspired c...
Peerzada, Kifa; Kurtuluş, Dilek Funda; Department of Aerospace Engineering (2023-1-10)
The unsteady behavior of the flow around a symmetric NACA 0014 airfoil is analyzed taking into consideration an oscillating motion in a sinusoidal pure-plunge mode as well as the stationary condition. Numerical simulations are performed by incorporating the two-dimensional unsteady, incompressible Navier-Stokes equation at Reynolds number (Re) = 10^4. The flow is visualized at the following two angle of attacks: 0^° and 4^°. The flow is assumed to be laminar at this Reynolds number. Flow properties such as:...
Steady-State CFD Analysis of 3D Bio-inspired Flapping Wing Models
Bektaş, Mürvet; Kurtuluş, Dilek Funda; Güler, Mehmet Ali (2018-07-11)
The aerodynamics of insects flying at low Reynolds numbers is considered for Micro Air Vehicles (MAV) designs. The aim of this study is to analyze different flapping wing models and to predict generated forces and vortices around the wings. The analyses are significant for understanding properties of flying animals like birds, insects and for improving MAVs more. For three insect species (namely, bumblebee, hawkmoth, and hummingbird), three dimensional (3D) wing models are numerically analyzed at different ...
Extremely Low Mitochondrial DNA Diversity in a near Threatened Species, the Cinereous Vulture Aegypius monachus in Turkey
Çakmak, Emel; Akin Pekçen, Çiǧdem; Kirazli, Cihangir; Yamaç, Elif; Bilgin, Cemal Can (2019-04-01)
The Cinereous Vulture Aegypius monachus is a near threatened raptor that occurs in isolated populations across its range. The only comprehensive genetic study performed so far excluded samples from Turkey, although this area forms a significant part of the species' range. In this study, we used 311 bp long sequences of the mitochondrial cytochrome b gene from 58 Turkish individuals to assess genetic diversity and phylogeny, and to determine if any signals for population expansion exist. Our phylogenetic ana...
Unsteady aerodynamics of a pitching NACA 0012 airfoil at low Reynolds number
Kurtuluş, Dilek Funda (SAGE Publications, 2019-11-01)
The present paper aims to investigate numerically small amplitude oscillation of NACA 0012 airfoil at Re = 1000. The airfoil is sinusoidally pitching around the quarter chord point with 1 degrees pitch amplitude about a mean angle of attack. The computations are performed for mean angles of attack ranging from 0 degrees to 60 degrees and for pitching frequencies of 1 Hz and 4 Hz. The effect of the mean angle of attack and pitching frequency on the instantaneous forces as well as the vortex structure is inve...
Citation Formats
T. AHMED, “UNSTEADY AERODYNAMICS OF CAMBERED AIRFOILS AT LOW REYNOLDS NUMBER,” M.S. - Master of Science, Middle East Technical University, 2022.