Evaluation of a CFD Program AEGIR (trademark) for Bare Hull Resistance and Seakeeping Prediction Capability
Final rept. May-Jul 2009
NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
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In this study, a 3D potential flow, panel method based CFD tool called AEGIRtrademark was assessed for predicting bare hull resistance and seakeeping performance. The program was run on mid-range personal computers, and analyses were performed on few different hullforms including the Joint High Speed Sealift JHSS monohull, a catamaran, a trimaran and a hard-chined semi-displacement monohull. Two different bow configurations, an elliptical shaped bulb and a gooseneck shaped bulb, were considered for the JHSS monohull bare hull resistance. For the catamaran and trimaran hullforms, the demihull and the center hull alone configurations were also considered for bare hull resistance. Measured data from model tests was used as a benchmark for validation. The focus was mainly on bare hull resistance with a very limited study on seakeeping. For all the hullforms and configurations, the coefficient of residuary resistance, sinkage and trim over a range of Froude numbers in calm water were obtained in AEGIRtrademark and compared with model test results. A limited set of seakeeping runs were performed in AEGIRtrademark on JHSS Monohull with gooseneck bulb and the catamaran demihull to obtain heave and pitch RAOs in regular head sea waves. The correlation between AEGIRtrademark and model test results for calm water performance bare hull resistance, sinkage and trim was excellent for the JHSS monohull configurations but was poor for other hullforms studied. The results are inconclusive for seakeeping assessment due to limited number of studies. The overall conclusion is that AEGIRtrademark performs well to predict calm water and head sea seakeeping performance for hullforms with small or no transoms.
- Computer Programming and Software
- Marine Engineering