CFD Simulation of PMM Motion in Shallow Water for the DTC Container Ship

International audienceThis paper is devoted to the validation exercises with the ISIS-CFD code conducted for the test cases proposed for the MASHCON conference. CFD simulations have been performed for the 4 different pure yaw and pure sway test cases under shallow water condition. Predicted results are compared with the measurement data provided by FHR

Bank effects for KVLCC2

A study is presented on ship–bank interaction effects in which viscous-flow solvers are used to predict the hydrodynamic forces and moments on the ship. The ship under consideration is the KRISO Very Large Crude Carrier (KVLCC2). For this hull form, Flanders Hydraulics Research (FHR) has conducted shallow water model tests in their towing tank equipped with surface-piercing banks and a vertical quay wall. The forces and moments on the KVLCC2 model were obtained for various water depths and lateral distances to the banks. Additionally, the wave elevation was measured between the quay wall and the ship model. In this study, two different CFD codes are used to predict the loads on the KVLCC2 as a function of the water depth and lateral position in the channel. The effect of propeller suction and free surface modelling on the results is quantified. Furthermore, comparisons will be made with CFD results from literature and potential flow computations to highlight the benefits of each approach. It will be shown that with careful setup of the computations, reliable predictions of the ship–bank interaction effects can be obtained

Towards performance optimisation in kayak using CFD

International audienceThis article summarizes the major part of the research project SOKA ”Simulation et Optimisation de canoës-KAyaks”, in collaboration with INRIA Sophia-Antipolis and the French Canoe Federation, founded by INSEP (the French National Institute of Sport and Physical Education) and the French ministry ”Ministère de la Ville de la Jeunesse et des Sports”.The main goal was to develop a procedure which includes experimenal measurements and advanced numerical simulation of the flow around the hull to deduce an analytical model of the global loads of the kayaker on his hull. This model was thus used to ad- dress and test an optimisation procedure based on unsteady CFD simulations with solved motions and analyse the influence of some parameters on the forward velocity of the hull

Towards automated computation with uncertainty estimation for industrial simulation of ship flow

Adaptive grid refinement is tested for routine, automated simulations of ship resistance in calm water. A simulation protocol for these computations is fine-tuned on one test case and then applied unchanged to three different cases. The solutions are numerically accurate and compare well with experiments. Effective numerical uncertainty estimation increases the trustworthiness of the solutions

The use of High-Performance Computing in nautical sports with a focus in hydrodynamics on rowing and kayaking

International audienc

Procédure de time-splitting pour la résolution de la fraction volumique dans le cas d'écoulements instationnaires

Les simulations numériques d'écoulements multifluides utilisant des schémas de capture d'interface souffrent de la contrainte sur le pas de temps imposée par la condition Courant-Friedrichs-Lewy (CFL). Nous proposons ici une méthode pour accélérer les calculs, appelée procédure time-splitting. L'équation de convection de la fraction volumique est résolue sur des pas de temps intermédiaires où la condition CFL est vérifiée. Elle permet ainsi l'utilisation d'un pas de temps global plus grand. Les développements ont été validés sur différents écoulements 2D. Nous présentons un cas test modélisant l'écoulement provoqué par une rupture de barrage suivie de l'impact sur un obstacle. Dans cet exemple, un facteur de réduction du temps de calcul allant jusqu'à 3 a été obtenu

TOWARDS UNSTEADY APPROACH FOR FUTURE FLUTTER CALCULATIONS

International audienc

Mission-based hull-form and propeller optimization of a transom stern destroyer for best performance in the sea environment

An overview is presented of the activities conducted within the NATO STO Task Group AVT-204 to “Assess the Ability to Optimize Hull Forms of Sea Vehicles for the Best Per- formance in a Sea Environment.” The objective is the development of a greater understanding of the potential and limitations of the hydrodynamic optimization tools. These include low- and high-fidelity solvers, automatic shape modification methods, and multi-objective optimiza- tion algorithms, and are limited here to a deterministic application. The approach includes simulation-based design optimization methods from different research teams. Analysis tools include potential flow and Reynolds-averaged Navier-Stokes equation solvers. Design modifica- tion tools include global modification functions, control point based methods, and parametric modelling by hull sections and basic curves. Optimization algorithms include particle swarm optimization, sequential quadratic programming, genetic and evolutionary algorithms. The ap- plication is the hull-form and propeller optimization of the DTMB 5415 model for significant conditions, based on actual missions at sea

Free-Surface Viscous Flow Solution Methods for Ship Hydrodynamics

The simulation of viscous free-surface water flow is a subject that has reached a certain maturity and is nowadays used in industrial applications, like the simulation of the flow around ships. While almost all methods used are based on the Navier-Stokes equations, the discretisation methods for the water surface differ widely. Many of these highly different methods are being used with success. We review three of these methods, by describing in detail their implementation in one particular code that is being used in industrial practice. The descriptions concern the principle of the method, numerical details, and the method’s strengths and limitations. For each code, examples are given of its use. Finally, the methods are compared to determine the best field of application for each. The following surface descretisation methods are reviewed. First, surface fitting/mesh deformation in PARNASSOS, developed by MARIN; the description focuses on the efficient steady-state solution method of this code. Then surface capturing with Volume-of-Fluid in ISIS-CFD, developed by CNRS/Ecole Centrale de Nantes; the main topic of this review are the compressive flux discretisation schemes for the volume fraction that are used in this code. And fi- nally, the Level Set method in SURF, developed by NMRI; this description contains a modified formulation of the Level Set method that is optimised for ship flow computation