The development and application of model reduction techniques have been widely investigated for problems in unsteady aerodynamic systems, driven mainly by the need to develop effective economical computational models capturing as much flow physics as possible. These techniques which have been based on a number of approaches such as balanced truncation, Arnoldi, proper orthogonal decomposition e...

A self-popped up flap is added to the airfoil (S809) suction surface improve aerodynamic performance under large angle of attack (AOA) inspired by slightly popped feathers on trailing edge a bird’s wing. The response methodology (RSM) optimization H, D, and θ conducted. lift–drag ratio an taken as target, Box–Behnken design adopted experiment scheme for θ. Multivariate quadratic polynomials are...

Three model problems were examined to assess the diiculties involved in using a hybrid scheme coupling ow computation with the the Ffowcs Williams and Hawkings equation to predict noise generated by v ortices passing over a sharp edge. The results indicate that the Ffowcs Williams and Hawkings equation correctly propagates the acoustic signals when provided with accurate ow information on the i...

The main purpose of this paper is to demonstrate a bionic design for the airfoil of wind turbines inspired by the morphology of Long-eared Owl's wings. Glauert Model was adopted to design the standard blade and the bionic blade, respectively. Numerical analysis method was utilized to study the aerodynamic characteristics of the airfoils as well as the blades. Results show that the bionic airfoi...

High-performance airfoils for transonic flows of Bethe–Zel’dovich–Thompson fluids are constructed using a robust and efficient Euler flow solver coupled with a multi-objective genetic algorithm. Bethe–Zel’dovich– Thompson fluids are characterized by negative values of the fundamental derivative of gasdynamics for a range of temperatures and pressures in the vapor phase, which leads to nonclassi...

A significant challenge to the application of evolutionary multiobjective optimization (EMO) for transonic airfoil design is the often excessive number of computational fluid dynamic (CFD) simulations required to ensure convergence. In this study, a multiobjective particle swarm optimization (MOPSO) framework is introduced, which incorporates designer preferences to provide further guidance in ...

Abstract. A gradient based method is presented for optimization of an airfoil configuration. The flow is governed by two dimensional, compressible Euler equations. A finite volume code based on unstructured grid is developed to solve the equations. The procedure is carried out for optimizing an airfoil with initial configuration of NACA 0012. The advantage of this technique over the other gradi...

We discuss a new numerical scheme involving adaptive boundary conditions which allows to compute, at very low Reynolds numbers, drag and lift of airfoils with rough surfaces efficiently with great precision. As an example we present the numerical implementation for an airfoil consisting of a line segment. The solution of the NavierStokes equations is singular at the leading and the trailing edg...

The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple stream tube (DSMT) model was applied for the performance prediction of straight bladed fixed pitch VAWT using NACA0018 airfoil at low wind speed. A moving mesh technique was used to investigate two-dimensional unsteady flow around the same VAWT model with NACA0018 airfoi...

In the paper, the authors view some ordinary differential equations and their solutions from the angle of (the generalized) derivative polynomials and simplify some known identities for the Bernoulli numbers and polynomials, the Frobenius-Euler polynomials, the Euler numbers and polynomials, in terms of the Stirling numbers of the first and second kinds.