Show/Hide Menu
Hide/Show Apps
Logout
Türkçe
Türkçe
Search
Search
Login
Login
OpenMETU
OpenMETU
About
About
Open Science Policy
Open Science Policy
Communities & Collections
Communities & Collections
Help
Help
Frequently Asked Questions
Frequently Asked Questions
Guides
Guides
Thesis submission
Thesis submission
MS without thesis term project submission
MS without thesis term project submission
Publication submission with DOI
Publication submission with DOI
Publication submission
Publication submission
Supporting Information
Supporting Information
General Information
General Information
Copyright, Embargo and License
Copyright, Embargo and License
Contact us
Contact us
Accuracy and efficiency improvements in finite difference sensitivity calculations
Download
index.pdf
Date
2007
Author
Özhamam, Murat
Metadata
Show full item record
Item Usage Stats
175
views
90
downloads
Cite This
Accuracy of the finite difference sensitivity calculations are improved by calculating the optimum finite difference interval sizes. In an aerodynamic inverse design algorithm, a compressor cascade geometry is perturbed by shape functions and finite differences sensitivity derivatives of the flow variables are calculated with respect to the base geometry flow variables. Sensitivity derivatives are used in an optimization code and a new airfoil is designed verifying given design characteristics. Accurate sensitivities are needed for optimization process. In order to find the optimum finite difference interval size, a method is investigated. Convergence error estimation techniques in iterative solutions and second derivative estimations are investigated to facilitate this method. For validation of the method, analytical sensitivity calculations of Euler equations are used and several applications are performed. Efficiency of the finite difference sensitivity calculations is improved by parallel computing. Finite difference sensitivity calculations are independent tasks in an inverse aerodynamic design algorithm and can be computed separately. Sensitivity calculations are performed on parallel processors and computing time is decreased.
Subject Keywords
Aerospace engineering.
,
Aeronautical engineering.
URI
http://etd.lib.metu.edu.tr/upload/12609128/index.pdf
https://hdl.handle.net/11511/17379
Collections
Graduate School of Natural and Applied Sciences, Thesis
Suggestions
OpenMETU
Core
Semi analytical study of stress and deformation analysis of anisotropic shells of revolution including first order transverse shear deformation
Oygür, Özgür Sinan; Kayran, Altan; Department of Aerospace Engineering (2008)
In this study, anisotropic shells of revolution subject to symmetric and unsymmetrical static loads are analysed. In derivation of governing equations to be used in the solution, first order transverse shear effects are included in the formulation. The governing equations can be listed as kinematic equations, constitutive equations, and equations of motion. The equations of motion are derived from Hamilton’s principle, the constitutive equations are developed under the assumptions of the classical laminatio...
Efficient structural optimization for multiple load cases using adjoint sensitivities
Akgun, MA; Haftka, RT; Wu, KC; Walsh, JL; Garcelon, JH (American Institute of Aeronautics and Astronautics (AIAA), 2001-03-01)
Adjoint sensitivity calculation of stress, buckling, and displacement constraints may be much less expensive than direct sensitivity calculation when the number of load cases is large. In general, it is more difficult to implement the adjoint method than the direct method, but it is shown that the use of the continuum adjoint method, along with homogeneity conditions, can alleviate the problem. Expressions for von Mises stress and local buckling sensitivities For isotropic plate elements are derived. Comput...
Time-domain calculation of sound propagation in lined ducts with sheared flows
Özyörük, Yusuf (American Institute of Aeronautics and Astronautics (AIAA), 2000-05-01)
A recent application of the time-domain equivalent of the classical acoustic impedance condition, i.e., the particle displacement continuity equation, to numerical simulations of a Bow-impedance tube in the time domain yielded reasonably good results with uniform mean flows. The present paper extends this application to include sheared mean-flow effects on sound propagation over acoustically treated walls. To assess the prediction improvements with sheared flows, especially at relatively high Mach numbers, ...
Nonlinear flutter calculations using finite elements in a direct Eulerian-Lagrangian formulation
Seber, Guclu; Bendiksen, Oddvar O. (American Institute of Aeronautics and Astronautics (AIAA), 2008-06-01)
A fully nonlinear aeroelastic formulation of the direct Eulerian-Lagrangian computational scheme is presented in which both structural and aerodynamic nonlinearities are treated without approximations. The method is direct in the sense that the calculations are done at the finite element level, both in the fluid and structural domains, and the fluid-structure system is time-marched as a single dynamic system using a multistage Runge-Kutta scheme. The exact nonlinear boundary condition at the fluid-structure...
Estimation of pico-satellite attitude dynamics and external torques via Unscented Kalman Filter
Söken, Halil Ersin (FapUNIFESP (SciELO), 2014-01-01)
In this study, an Unscented Kalman Filter (UKF) algorithm is designed for estimating the attitude of a picosatellite and the in-orbit external disturbance torques. The estimation vector is formed by the satellite's attitude, angular rates, and the unknown constant components of the external disturbance torques acting on the satellite. The gravity gradient torque, residual magnetic moment, sun radiation pressure and aerodynamic drag are all included in the estimated external disturbance torque vector. The sa...
Citation Formats
IEEE
ACM
APA
CHICAGO
MLA
BibTeX
M. Özhamam, “Accuracy and efficiency improvements in finite difference sensitivity calculations,” M.S. - Master of Science, Middle East Technical University, 2007.