An Automatic Grid Generation Program for Potential Flow Code Using in the Optimal Trim Angle Analysis of the Ship
Date Issued
2010
Date
2010
Author(s)
Chiang, Chia-Yen
Abstract
Varying trim angle by adjusting the distribution of ballast water to reduce the resistance during real sea operation is considered to be an economic way to save energy. In the thesis CFD approach is chosen to evaluate the resistance of ships running in calm water with different trim angles. The optimal trim angles are recorded as a database for real-time queries.
The BEM implementation of CFD approach to solve potential flow problems is faster than FVM. The grids of the hull surfaces and the free surface are required for panel methods. In this report an intermediary program which bridges the gap between the commercial CAD software, “FRIENDSHIP Framework” and the potential flow code from USDDC is built up. The program automatically generates on-surface structural grids as panels’ descriptions, thereby speeding up the process of resistance evaluation. Three key procedures and one refining technique are implemented in the program. The modules are coded in Fscript and C language and they work collaboratively in the FRIENDSHIP Framework.
A comprehensive comparison between the automatic grid and the manual grid generated by Gridgen is included. The grid independence of the program has been verified via wave-making resistance coefficients and applied on a containership and a tanker to demonstrate the procedure and algorithm adapted to different hull forms. On the other hand, for each displacement and ship speed there exists an optimal trim angle, which is 11% of total resistance reduction than the even keel condition.
Subjects
automatic grid
potential flow
wave-making resistance
trim angle
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-99-R97525007-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):562e15319949460bd7e19b6ee4727700