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Author : Janek Meyer
Results 1 - 4 of 4
Investigation of Modern Sailing Yachts Using a New Free-Surface RANSE Code
A new free surface flow RANSE solver has been developed based on the OpenFOAM framework. The solver addresses some of the main deficiencies of OpenFOAM’s standard free surface solver. It uses advanced higher order discretization schemes for the volume of fluid variable, a reconstruction of the pressure at the free surface for proper treatment of the jump of the pressure gradient at the free surface and a special method for the generation and damping of sea waves and ship generated waves at inlet and outlet of the flow domain. This new solver is used for the simulation of advanced flow problems for sailing yachts and small boats: resistance investigations at very high Froude number, investigation of the behaviour of sailing yachts in head waves and the surfing behaviour of a sailing yacht in following waves. The paper outlines the new solver and presents some case studies demonstrating its abilities.
Prediction and optimization of aerodynamic and hydrodynamic forces and boat speed of foiling catamarans with a wing sail and a jib
This paper describes a method to calculate the
aerodynamic forces generated by a rigid two-element wing
together with a jib. Additionally, investigations of
hydrodynamic flow forces generated by water-piercing Lshaped
foils are introduced. The aerodynamic and
hydrodynamic flow force prediction methods are combined
in a velocity prediction program featuring a constraint
optimization method in order to predict boat speed and wing
and foil trimming parameters for its maximization.
A velocity polar calculated by applying this method to a
50-foot catamaran is shown and the result of some studies
are presented, varying design parameters of the catamaran.
Advanced CFD-Simulations of Free-Surface Flows Around Modern Sailing Yachts Using a Newly Developed OpenFOAM Solver
While plain vanilla OpenFOAM(OF) has strong capabilities with regards to quite a few typical CFD-tasks, some problems actually require additional solvers and numerical methods for efficient computation of high-quality results. One of the fields requiring these additions is the computation of large-scale free-surface flows as found e.g. in naval architecture. This holds especially for the flow around typical modern yacht hulls, often planing, sometimes with surfacepiercing appendages. Particular challenges include, but are not limited to, breaking waves, sharpness of interface, numerical ventilation (aka streaking) and a wide range of flow phenomenon scales. A new OF-based application including newly implemented discretisation schemes, gradient computation and rigid body motion computation is described. The new code is validated against published experimental data; the effect on accuracy, computational time and solver stability is shown by comparison to standard OF-solvers (interFoam / interDyMFoam) and Star-CCM+. The code’s capabilities to simulate complex ”real-world” flows are shown on a well-known racing yacht design.
A Measurement System for Performance Monitoring on Small Sailing Dinghies
This paper describes a new performance
monitoring system for dinghies and small sailing boats,
developed in a collaborative project of the Yacht Research
Unit Kiel (YRUK) and the Mads Clausen Institute (MCI)
of the University of Southern Denmark. The system under
development features a complete set of nautical
instruments (wind, boat speed and heading, position) as
well as dynamic sensors measuring the motion of the
dinghy with additional audio and video streams for crew
observations. Most sensors are integrated in a small
lightweight housing also containing a main processing unit
to be mounted on a dinghy. Some external miniaturized
sensors (wind and water anemometers) are connected
wirelessly. Data and media streams are recorded. Further a
telemetry system allows online data transmission to a
remote client operated on a coach boat. Analysis software
allows the coach to visualize and analyze the performance
of the dinghy. Both, the hardware system and the analysis
software are presented here including first results from a
field trial.