Download or read book Infeasible Path Methods for an Aerodynamic Shape Optimization Problem written by Omar Ghattas and published by . This book was released on 1992 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "We consider optimal design problems of systems governed by suitable discretizations of nonlinear partial differential equations. We present and examine a coordinate basis infeasible path method tailored to such design problems. We employ a particular null space representation which exploits the structure of the constraint Jacobian. The resulting method avoids resolution of the nonlinear behavior for each design iterate. Three variants of the method are developed which require the solution of either two or three linear systems involving the stiffness matrix of the discrete boundary value problem. The method is used to solve an aerodynamic design problem governed by nonlinear potential flow. Numerical results demonstrate a substantial performance improvement."
Download or read book Massively Parallel Aerodynamic Shape Optimization written by Carlos E. Orozco and published by . This book was released on 1992 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "We consider the problem of finding the shape of an airfoil which produces a pressure distribution closest to a desired one. The flow is modeled by the nonlinear potential equations of compressible flow. The problem is formulated as an optimization problem constrained by a discrete approximation to a nonlinear boundary value problem. We present a new parallel infeasible path method for this class of optimization problem. The method is based on a null space representation tailored to the structure of the constraint Jacobian matrix. The resulting null space projections formally involve inverses of the stiffness matrix. The algorithm requires only two stiffness matrix solves per optimization iteration, in contrast to a conventional path-following method, which resolves the full physics at each iteration. The algorithm has been implemented on a CM-2, and requires no new data structures or communication patterns beyond those needed for numerical solution of the boundary value problem. We discuss numerical evidence for the superiority of the new method relative to a conventional path-following approach."
Download or read book The Variational Method for Aerodynamic Optimization Using the Navier Stokes Equations written by and published by . This book was released on 1997 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the formulation of an aerodynamic shape design methodology using a compressible viscous flow model based on the Reynolds Averaged Navier Stokes equations. The aerodynamic shape is described by a set of geometrical design variables. The design problem is formulated as an optimization problem stated in terms of an aerodynamic objective functional which has to be minimized. The design scheme employs a gradient based optimization algorithm in order to obtain the optimum values of the design variables. The gradient of the aerodynamic functional with respect to the design variables is computed by means of the variational method, which requires the solution of an adjoint problem. The formulation of the adjoint problem is described which leads to a set of adjoint equations and boundary conditions. Using the flow variables and the adjoint variables, an expression for the gradient has been constructed. Computational results are presented for an inverse problem of an airfoil. It will be shown that, starting from an initial geometry of the NACA 0012 airfoil, the target pressure distribution and geometry of a best fit of the RAE 2822 airfoil in a transonic flow condition has been reconstructed successfully.
Download or read book One shot Methods for Aerodynamic Shape Optimization written by Emre Özkaya and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2007 with total page 960 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerodynamic Shape Optimization Using Control Theory written by James John Reuther and published by . This book was released on 1996 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Aerodynamic shape design has long persisted as a difficult scientific challenge due [sic] its highly nonlinear flow physics and daunting geometric complexity. However, with the emergence of Computational Fluid Dynamics (CFD) it has become possible to make accurate predictions of flows which are not dominated by viscous effects. It is thus worthwhile to explore the extension of CFD methods for flow analysis to the treatment of aerodynamic shape design. Two new aerodynamic shape design methods are developed which combine existing CFD technology, optimal control theory, and numerical optimization techniques. Flow analysis methods for the potential flow equation and the Euler equations form the basis of the two respective design methods. In each case, optimal control theory is used to derive the adjoint differential equations, the solution of which provides the necessary gradient information to a numerical optimization method much more efficiently then [sic] by conventional finite differencing. Each technique uses a quasi-Newton numerical optimization algorithm to drive an aerodynamic objective function toward a minimum. An analytic grid perturbation method is developed to modify body fitted meshes to accommodate shape changes during the design process. Both Hicks-Henne perturbation functions and B-spline control points are explored as suitable design variables. The new methods prove to be computationally efficient and robust, and can be used for practical airfoil design including geometric and aerodynamic constraints. Objective functions are chosen to allow both inverse design to a target pressure distribution and wave drag minimization. Several design cases are presented for each method illustrating its practicality and efficiency. These include non-lifting and lifting airfoils operating at both subsonic and transonic conditions."
Download or read book Gradient based Aerodynamic Shape Optimization Using ADI Method for Large scale Problems written by Mohagna J. Pandya and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Preconditioning Method for Shape Optimization Governed by the Euler Equations written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-09 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: We consider a classical aerodynamic shape optimization problem subject to the compressible Euler flow equations. The gradient of the cost functional with respect to the shape variables is derived with the adjoint method at the continuous level. The Hessian (second order derivative of the cost functional with respect to the shape variables) is approximated also at the continuous level, as first introduced by Arian and Ta'asan (1996). The approximation of the Hessian is used to approximate the Newton step which is essential to accelerate the numerical solution of the optimization problem. The design space is discretized in the maximum dimension, i.e., the location of each point on the intersection of the computational mesh with the airfoil is taken to be an independent design variable. We give numerical examples for 86 design variables in two different flow speeds and achieve an order of magnitude reduction in the cost functional at a computational effort of a full solution of the analysis partial differential equation (PDE). Arian, Eyal and Vatsa, Veer N. Langley Research Center NASA/CR-1998-206926, NAS 1.26:206926, ICASE-98-14 NAS1-19480; RTOP 505-90-52-01...
Download or read book Approximate Partially Reduced SQP Approaches for Aerodynamic Shape Optimization Problems written by Ilia Gherman and published by . This book was released on 2008 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, a new optimization method is developed which is especially efficient in aerodynamical shape optimization. In dieser Dissertation wird eine neue Optimierungsmethode vorgestellt, die effizient bei der aerodynamischen Formoptimierung eingesetzt werden kann.
Download or read book An Efficient Method for Aerodynamic Shape Optimization written by Subhendu Bikash Hazra and published by . This book was released on 2004 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adjoint Methods for Aerodynamic Shape Optimization written by Gábor Povorai and published by . This book was released on 2020 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: This master thesis investigated the applicability of the Hicks-Henne bump functions and Free-Form Deformation as shape deformation methods used for aerodynamic shape optimization by the adjoint method. In order to alleviate user effort in the setup of simulations and post-processing of results, a MatLab framework has been developed. This framework integrated shape definition, meshing, file management, flow solver and post-processing tools. The external tools were open-source software. to allow the use of arbitrary cell and processor core numbers. The computational fluid dynamics solver, SU2 was used to obtain direct flow and adjoint solutions and to perform shape deformations using the built in nonlinear constrained optimization function. Automatic mesh generation was done using GMSH. The thesis focused on inviscid and viscous 2D problems in the transonic and supersonic flow regimes. The definition of the initial aerodynamic shapes was done using the Class-Shape Transformation method. The test cases optimization problems with the NACA0012 airfoil as the initial airfoil for deformation, with drag reduction as the objective function. The test cases involved different constraints e.g. airfoil thickness, lift coefficient and pitching moment coefficient. Comparisons were made between the two methods in terms of performance in the minimization of the objective function. The results of the optimization problems were compared to reference airfoils from literature. Both deformation methods proved to be effective, clear superiority of one method over the other could not be shown.*****This master thesis investigated the applicability of the Hicks-Henne bump functions and Free-Form Deformation as shape deformation methods used for aerodynamic shape optimization by the adjoint method. In order to alleviate user effort in the setup of simulations and post-processing of results, a MatLab framework has been developed. This framework integrated shape definition, meshing, file manage
Download or read book Aerodynamic Shape Optimization Techniques Based on Control Theory written by Antony Jameson and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerodynamic Shape Optimization by Means of Sequential Linear Programming Techniques written by Giampietro Carpentieri and published by . This book was released on 2007 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Methods for Aerodynamic Shape Optimization written by Olivier Amoignon and published by . This book was released on 2005 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Numerical Methodology for Aerodynamic Shape Optimization in Turbulent Flow Enabling Large Geometric Variation written by Lana Osusky and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Optimal Control Theory Based Algorithm to Solve 2D Aerodynamic Shape Optimisation Problems for Inviscid and Viscous Flows written by S. Hiernaux and published by . This book was released on 2000 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the capacity of today's computers; one can envisage the resolution of shape optimization problems in aerodynamics. Nevertheless, optimization methods require many evaluations of different aerodynamic configurations, and so are much more expensive than a single analysis. It is therefore mandatory to find methods that evaluate aerodynamic functions and their gradient at the lowest possible computational cost; as well as fast and robust optimization methods.
Download or read book Simultaneous Pseudo timestepping for Aerodynamic Shape Optimization Problems with State Constraints written by Subhendu Bikash Hazra and published by . This book was released on 2004 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
