Download or read book Coupling Linearized Far Field Boundary Conditions with Nonlinear Near Field Solutions in Transonic Flow written by and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research has been conducted to evaluate the feasibility of coupling linearized far-field solutions with near-field finite difference equations to reduce the number of unknowns and thus the computer resources required in transonic flow calculations. For two dimensional flow, changes to an existing finite difference program involved distributing sources on the grid boundary in order to obtain the proper far field outgoing wave boundary conditions on a reduced grid. Validation of the matching procedure was made for zero thickness airfoils by comparison of the results with those of the kernel function method. For airfoils with finite thickness, a criterion based on the gradient of the flowfield Mach number was developed for establishing the minimum size finite difference region necessary for accurate unsteady calculations. This approach could not be applied directly to three-dimensional flow because of the large number of variables required in the exterior solution. However, it is shown that the number of unknowns can be reduced to a practical number by using both source and doublet distributions on the boundaries, describing these distributions with low-order polynomials, and using a least squares procedure to satisfy the matching conditions across the boundaries. Solutions for the flow over a wing of vanishing thickness were in very good agreement with results from original finite difference technique and with the kernel function method. Solutions for a wing thickness were in good agreement with results from the original finite difference technique. The pilot program used for this study is limited to rectangular wings.
Download or read book Coupling Linearized Far Field Boundary Conditions with Nonlinear Near Field Solutions in Transonic Flow written by and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research has been conducted to evaluate the feasibility of coupling linearized far-field solutions with near-field finite difference equations to reduce the number of unknowns and thus the computer resources required in transonic flow calculations. For two dimensional flow, changes to an existing finite difference program involved distributing sources on the grid boundary in order to obtain the proper far field outgoing wave boundary conditions on a reduced grid. Validation of the matching procedure was made for zero thickness airfoils by comparison of the results with those of the kernel function method. For airfoils with finite thickness, a criterion based on the gradient of the flowfield Mach number was developed for establishing the minimum size finite difference region necessary for accurate unsteady calculations. This approach could not be applied directly to three-dimensional flow because of the large number of variables required in the exterior solution. However, it is shown that the number of unknowns can be reduced to a practical number by using both source and doublet distributions on the boundaries, describing these distributions with low-order polynomials, and using a least squares procedure to satisfy the matching conditions across the boundaries. Solutions for the flow over a wing of vanishing thickness were in very good agreement with results from original finite difference technique and with the kernel function method. Solutions for a wing thickness were in good agreement with results from the original finite difference technique. The pilot program used for this study is limited to rectangular wings.
Download or read book Coupling Linearized Far field Boundary Conditions with Nonlinear Near field Solutions in Transonic Flow written by William S. Rowe and published by . This book was released on 1988 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 956 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA SP written by and published by . This book was released on 1992 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Memorandum written by and published by . This book was released on 1986 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adaptive Wall Wind Tunnels A Selected Annotated Bibliography written by Marie H. Tuttle and published by . This book was released on 1986 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering written by and published by . This book was released on 1990 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA).
Download or read book Aeronautical Engineering A Cumulative Index to a Continuing Bibliography supplement 248 written by and published by . This book was released on 1990 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Finding Guide to AIAA Meeting Papers written by American Institute of Aeronautics and Astronautics. Technical Information Service and published by . This book was released on 1990 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1969 with total page 1090 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 890 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow Field Matching written by Lawrence J. Dickson and published by . This book was released on 1978 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a transonic flow problem with subsonic freestream in an untransformed infinite flow field, the outer boundary conditions are hard to apply. By assuming that the flow outside an artificial matching boundary is subcritical and linear, a Prandtl-Glauert solution is used (generated by panels of Green's function integrals along the matching boundary) in the far field, while solving the near field by finite differences. The two solutions are joined iteratively by requiring continuity of potential and normal derivative across the matching boundary. Two refinements of this method are examined, also. In one, a locally linearized second-order far field solution (a Poisson equation solution) is used. In the second, a middle field inhabited by large rectangular finite elements is used in the area where the flow is highly nonlinear but still subcritical. This report details only the finite element results, the earlier ones having already been published.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index Keyword A L written by and published by . This book was released on 1986 with total page 1164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structural dynamics written by and published by . This book was released on 1985 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt:
