The overall aim of the Numerical Towing Tank, WP 1 is to improve the accuracy, reliability and applicability of existing state-of-the-art CFD codes, through improving problem set-up and methodology, to develop a viable alternative to the physical towing tank testing in the prediction of hydrodynamic performance of ships, in particular the speed-power relationship, at the design stage. The application of the methods in dedicated optimisation process will be a second main objective. To this end and to enable further exploitation of CFD techniques in ship design, the following objectives are targeted:

  • Enhancement of the predictive capability through improved flow modelling; advanced modelling techniques for turbulence, free surface including transom stern flow, hull roughness and propulsors will be tested for selected test cases and their influence on accuracy in predicting resistance and propulsion performance will be carefully studied.
  • Further developments of basic numerics and verification; improved discretisation schemes and adaptive grids will be developed, and efficiency will be improved. Extensive uncertainty analysis will be undertaken for parameters that influence the quantitative accuracy of performance prediction; a systematic investigation will be made of the effects of grid type, structure and resolution on accuracy and efficiency; different expressions and different orders of numerical approximation will be tested for numerical accuracy of the prediction of wake, resistance and propulsion and particular scale effects.
  • Validation of the newly developed numerical methods and techniques for selected test cases; the validation study will include prediction of all resistance components (hull only) and propeller open water characteristics (propeller only), propulsion test simulation (hull + propeller) and nominal wake computation; full scale extrapolation techniques and particular scale effects will be investigated and new “correlation allowances” for CFD-based extrapolation techniques will be proposed.
  • Integration of the validated (for quantitative accuracy of resistance/propulsion performance prediction) CFD codes with geometry variation/modification modules and optimisation and sensitivity analysis routines, thus facilitating hull form changes towards improved designs and multi-disciplinary optimisation; the CFD codes developed should be capable of predicting the hydrodynamic performance of ships accurately enough for design optimisation purposes and for handling different types of hull geometries and propulsors.

Description of work:
This work programme contains the following three development tasks:

Task 1.1: The resistance tests
Task 1.2: Hull/propeller interaction – the propulsion tests
Task 1.3: Provision of hull form modification - Optimisation.

The method of predicting propeller open water characteristics will be developed in cooperation with WP4. The multi-objective optimisation in the field of resistance and propulsion will be investigated in WP1 but multi-criteria optimisation problems involving other hydrodynamic performances will be dealt with in WP5.

Developments to be made in WP1 will provide a basic input to other work packages. The results of flow prediction derived in WP1 will be used for further analysis of propeller cavitation (WP4), seakeeping (WP2) and manoeuvring (WP3) characteristics of ships and to input data to Integration (WP5) for visualisation purposes. Moreover, developments on numerical accuracy and efficiency encompass a much wider scope than just WP1 and directly benefit the other work packages which use the same RANS codes as considered in WP1.

During the first 18 months the project will focus on the resistance prediction, both the numerical accuracy aspect and the extended modelling. The work on the numerical propulsion test will be done in the next phase of the project. The results of both activities will be used in the optimisation work that is mainly done towards the end of the project.

THE PROJECT | WP 1 | WP 2 | WP 3 | WP 4 | WP 5