On the Unsteady Behavior of the Flow Around NACA 0012 Airfoil with Steady External Conditions at Re=1000

Even for the stationary airfoils, due to the boundary and shear layer interactions of upper and lower surface of the airfoils, alternating vortex patterns form and the flow becomes time dependent. In the current study, the unsteady behavior of the flow around a symmetric airfoil is considered as incidence angle increases. The flow patterns are presented for wide range of angles of attack values. The vortex pattern generated is analyzed numerically for different angles of attack at Re=1000 around NACA 0012 airfoil. At this Reynolds number, the flow is laminar and boundary layers are quite thick. Flow separation and unsteady vortex shedding is observed even at low angles of attack. For NACA 0012 airfoil, the unsteady vortex pattern is observed at about 8 degrees angle of attack for Re=1000. Spectral analysis is performed for angles of attack ranging from 0 degrees to 90 degrees. It is presented that amplitude spectrum of lift coefficient (C-l) start to shows a peak at 8 degrees for NACA 0012 and the aerodynamic forces presents oscillatory behavior afterwards. The effect of angle of attack to wake pattern and instantaneous and mean aerodynamic coefficients are discussed. The time-averaged streamlines, pressure and skin friction coefficients are analyzed to observe the vortex formation and separation from the airfoil upper surface at this low Reynolds number.


On the wake pattern of symmetric airfoils for different incidence angles at Re=1000
Kurtuluş, Dilek Funda (SAGE Publications, 2016-06-01)
In the current study, numerical simulations are performed in order to investigate effects of incidence angle and airfoil thickness on alternating vortex pattern of symmetric airfoils at Re = 1000. This alternating vortex pattern is found to be significantly varying in shape as the incidence angle increases. The results are obtained with 1 degrees increment from 0 degrees to 41 degrees and then with 10 degrees increment from 40 degrees until 180 degrees. The instantaneous and mean vortex patterns are investi...
On the outburst light curves of soft X-ray transients as response of the accretion disk to mass deposition
Ertan, U; Alpar, MA (1998-08-01)
We note that the solution of accretion disk dynamics for an initial delta-function mass distribution gives a light curve that fits both the rise and the decay pattern of the outburst light curves of black-hole Soft X-ray transients (BSXTs) until the onset of the first mini outburst quite well. The Green's function solution of Lynden-Bell & Pringle (1974) is employed for two different time-independent viscosity laws to calculate the expected count rates of X-ray photons in the Ginga energy bands as a functio...
Approximate Stable Diagonalization of the Green's Function for Low Frequencies
Ergül, Özgür Salih (Institute of Electrical and Electronics Engineers (IEEE), 2014-01-01)
We present an approximate diagonalization of the Green's function that is stable at arbitrarily short distances with respect to wavelength. The diagonalization is based on scaled spherical functions and plane waves, where a scaling factor is used to stabilize special functions with small arguments. Optimization of the scaling factor leads to accurate diagonalizations, which can be used to implement the multilevel fast multipole algorithm for low-frequency problems.
On the collisional damping of giant dipole resonance
Yılmaz, Osman; Yildirim, S; Ayik, S (Elsevier BV, 2000-01-20)
Collisional damping widths of giant dipole excitations are calculated in Thomas-Fermi approximation by employing the microscopic in-medium cross-sections of Li and Machleidt and the phenomenological Gogny force. The results obtained in both calculations compare well, but account for about 25-35% of the observed widths in Sn-120 and (208)pb at finite temperatures. (C) 2000 Published by Elsevier Science B.V. All rights reserved.
Analysis of the Raman frequency as an order parameter close to the melting point in biphenyl
Yurtseven, Hasan Hamit (2017-05-01)
We analyze the observed Raman frequencies of the three lattice modes (modes A, B and 70cm-1) near the melting point in biphenyl by calculating the temperature dependence of the order parameter from the mean field theory. This is based on the correlation between the frequency and the order parameter close to the melting temperature (Tm=343K) in biphenyl. The Raman frequencies of the modes A and B decrease rapidly as the melting temperature is approached, whereas the Raman frequency of the 70 cm-1 is smoothly...
Citation Formats
D. F. Kurtuluş, “On the Unsteady Behavior of the Flow Around NACA 0012 Airfoil with Steady External Conditions at Re=1000,” INTERNATIONAL JOURNAL OF MICRO AIR VEHICLES, pp. 301–326, 2015, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/38357.