G.C. Bourantas¹, E.D. Skouras^2,3, V.C. Loukopoulos⁴, G.C. Nikiforidis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.59, No.1, pp. 31-64, 2010, DOI:10.3970/cmes.2010.059.031

Abstract A meshfree point collocation method has been developed for the velocity-vorticity formulation of two-dimensional, steady state incompressible Navier-Stokes equations. Particular emphasis was placed on the application of the velocity-correc -tion method, ensuring the continuity equation. The Moving Least Squares (MLS) approximation is employed for the construction of the shape functions, in conjunction with the general framework of the point collocation method. Computations are obtained for regular and irregular nodal distributions, stressing the positivity conditions that make the matrix of the system stable and convergent. The accuracy and the stability of the proposed scheme are demonstrated through two representative, well-known, and… More >

Ori Levin, Wei Shyy¹

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.4, pp. 523-536, 2001, DOI:10.3970/cmes.2001.002.523

Abstract Typical low Reynolds number airfoils suffer from reduced lift-to-drag ratio and are prone to flow separation. In order to improve the aerodynamic performance of such airfoils in an unsteady freestream, the concept of passive control is investigated. In this study, a membrane with varying thickness distribution and mechanical properties is attached on the upper surface of a modified Clark-Y airfoil and is free to move upwards and downwards in response to the pressure difference across it. The response surface method is employed to investigate the individual and collective effects of the membrane's prestress, elastic modulus, and thickness distribution on aerodynamic… More >

A. Abbassi^1,2, N. Kechiche¹, H. Ben Aissia¹

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.3, pp. 319-341, 2014, DOI:10.3970/fdmp.2014.010.319

Abstract Jet transition towards a turbulent state is an interesting topic requiring a detailed analysis of the process leading to the onset and amplification of small flow disturbances. Here we examine experimentally the transition process for an isothermal laminar round free jet at low values of the Reynolds number. Close to the inlet nozzle, the turbulence intensity is assumed to be small enough so that the initial shear layer can be considered laminar and the velocity profile uniform. Experimental data are obtained using a Laser Doppler Anemometry (LDA) technique at various longitudinal and transversal coordinates, (x,y). Spectral analysis of the instantaneous… More >

E. A. El-Abeedy¹, A. A. Busedra¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 153-167, 2013, DOI:10.3970/fdmp.2013.009.153

Abstract Fully developed laminar mixed convection in inclined semicircular ducts is investigated numerically for the specific case of uniform heat input along the axial direction and uniform peripheral wall temperature, H1. The duct is considered over a variety of orientations (rotations) of its cross section, ranging from 0° (flat wall horizontally facing upward) to 180° (flat wall horizontally facing downward) with increment of 45° and a fixed inclination of its axis (with respect to the direction of gravity). In particular, the following conditions are considered: inclination α = 20°, 300 ≤ Re ≤ 1000, Pr = 4 and Gr = 1… More >

Chein-Shan Liu¹

CMC-Computers, Materials & Continua, Vol.9, No.3, pp. 229-252, 2009, DOI:10.3970/cmc.2009.009.229

Abstract When the given input data are corrupted by an intensive noise, most numerical methods may fail to produce acceptable numerical solutions. Here, we propose a new numerical scheme for solving the Burgers equation forward in time and backward in time. A fictitious time τ is used to transform the dependent variable u(x,t) into a new one by (1+τ )u(x,t) =: v(x,t,τ), such that the original Burgers equation is written as a new parabolic type partial differential equation in the space of (x,t,τ). A fictitious damping coefficient can be used to strengthen the stability in the numerical integration of a semi-discretized… More >