TELFER’S GEOSIM METHOD REVISITED BY CFD

In this study, Telfer’s GEOSIM method for the computation of ship resistance at full scale has been applied by CFD (Computational Fluid Dynamics) approach. For this purpose, the KCS (KRISO Container Ship) hull has been investigated numerically with k-ε turbulence model for three different scales and full scale analyses by URANS (Unsteady Reynolds Averaged Navier-Stokes) method. Full scale ship resistance has been predicted using the numerical results computed at different model scales by Telfer’s GEOSIM method. The numerical results at three scales have also been extrapolated separately to that at full scale by ITTC 1978 performance prediction method. An experimental study has also been carried out at a model scale for validation. The results by Telfer’s GEOSIM method have been calculated almost in full compliance with those of CFD approach. While the difference between the results of CFD and those of ITTC extrapolation method is about 5% at full scale, the difference between the results of CFD and those of Telfer’s GEOSIM method has been found to be less than 1% at full scale. In addition, this method has been applied to estimate the nominal wake coefficient at full scale from model scales. A very good correlation has also been found for nominal wake coefficient.

Experimental model tests to improve a tanker resistance performance

The ship resistance is one of the most important hydrodynamics performances, being related to the contractual ship speed. The experimental model tests can be used to measure and improve the resistance performance. In this paper, the possibility of using the experimental techniques in order to improve a tanker model resistance is demonstrated, based on a bulbous bow modelling solution. In this context, the results obtained in the Towing Tank of the Naval Architecture Faculty of “Dunarea de Jos” University of Galati, related to a tanker model resistance with and without bulbous bow are presented. The bulbous bow form was realised based on the hydrodynamics principles adapted to the bow forms of the tanker. In the case of the bulbous bow solution, a significant reduction of over 8% of the tanker model resistance was obtained, in the design speed domain.

Ship resistance performances assessment for a containership

The present work is focused on ship resistance performances assessment for a given capacity containership. Starting from the main dimensions of a parent ship, other ten hull forms have been generated using DELFTship free program. For each case, the hydrodynamic ship resistance has been calculated using an inhouse code. The objective was to modified some geometrical parameters to obtain shapes of the hull that would provide the least resistance at the required transport capacity. The results obtained will be used in a future analysis related to the impact of hull forms improvements and ship resistance reduction on the propulsive performance and CO2 emissions per transport work.

Benchmark Study of FINETM/Marine CFD Code for the Calculation of Ship Resistance

Benchmarking can be used to test CFD programs for selecting turbulence models, grid dependency studies, testing different numerical schemes and source codes, and testing different boundary conditions. CFD simulation in this study uses FINE™/Marine 7.2-1 software. The solver process at NUMECA uses the ISIS-CFD flow solver developed by EMN, which uses the incompressible unsteady Reynolds-average Navier stoke equation (RANSE). The solver is based on the finite volume method, and Turbulence models use SST k-ω models. The free surface flow around a model surface ship (DTMB 5415) advancing in calm water under steady conditions is numerically simulated. The geometry of the DTMB 5415 ship hull was provided in igs file format. The 1996 International Towing Tank Conference has recommended the DTMB 5415 combatant as a benchmark case for CFD computations of ship resistance and propulsion. The results compare well with the available experimental data. They allow an understanding of the differences that can be expected from vicious and potential flow methods due to their different mathematical formulations. It is demonstrated that the complementary application of these methods allows good predictions of the total ship resistance.