Return to the Table of ContentsObjective: Develop a surface/volume grid generator which is capable of generating Computational Fluid Dynamics (CFD) quality grids and updating existing grids to reflect geometric changes defined by an automated design and optimization process.
Approach: The Coordinate and Sensitivity Calculator for Multi-disciplinary Design Optimization (CSCMDO) functions as a general purpose multi-block CFD volume grid generator. In addition to the generation of block interiors, existing surfaces of a block may be updated according to an input surface network(s) of discrete points. The input surface network(s) define geometric changes which are to be reflected in the CFD grid. The 3D interpolation of block interiors has been implemented using SONI arclength-based blending functions. Blocks may be automatically subdivided using intermediate ''hard planes'' to further control 3D interpolation. Hard planes may be input or calculated within CSCMDO using arclength-based interpolation. The program runs in the batch environment which allows for integration directly into the design loop, as shown in the attached figure. Program flow is controlled via an ASCII user input deck. Along with the input deck, a file containing grid point definitions for the six faces of each block is input. The block faces define the grid topology, number of points in the block, relative spacing, etc. Both of these files are generated outside of the design loop. With this information, the code generates modified volume grids based on the surfaces created by the design and optimization process. The code is written entirely in ANSI C and utilizes I/O formats which are widely used in the field of CFD.
Accomplishment: CSCMDO is capable of generating CFD quality surface and volume grids given a defined topology, a user input file, and any surfaces needed to drive the updates. The orientation of the existing grid to the surface network(s) is determined automatically or may be specified manually. The program uses dynamic memory allocation for problem size independence. Output is in the form of a PLOT3D Multi- block 3D/Whole volume grid file and may be in ASCII, C Binary, or FORTRAN Unformatted formats. The code is portable and has been tested on UNIX platforms including the Silicon Graphics Iris and Hewlett Packard workstations and Cray Mainframes. CFD quality Euler type surface and volume grids have been successfully generated for HSCT type wing/body/tail combinations using CSCMDO.
Significance: The CSCMDO multi-purpose volume grid generator removes the human from the labor intensive grid generation phase of the design loop and provides for the automated update of CFD volume grids in the design and optimization process.
Status/Plans: Current work with CSCMDO is focused on the proof-of-concept for a wing/body/tail configuration with engine nacelles and pylons. The work includes the addition of necessary coding to accommodate the more complicated geometries, as well as the establishment and execution of a test suite. Work is also planned for the generation of Navier-Stokes quality volume grids, computation of volume grid sensitivity derivatives, and the incorporation of CSCMDO into the Framework for Interdisciplinary Design Optimization (FIDO). Points of Contact:
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