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Although the topic of roll damping of vessels at sea is already brought to the attention of naval architects by Froude more than 100 years ago, the physics of it remain intriguing, even today. An accurate prediction of the motions of offshore structures in harsh environments, designed for 25 years continuous operation, is the topic of this paper. Model test experiments for two FPSO’s developed by SBM for Petrobras are discussed. It is shown that the FPSO submerged riser balcony on one side of the vessel contributes to the roll damping through similar physics as the bilge keel does.Flow memory...
The continuously increasing computer power has made it possible to make performance calculations based on RANS CFD method for propellers within commercial acceptable lead times nowadays. Wärtsilä has decided to extent the scope of the numerical analyses, to include the ship hull geometry as well. The final goal is to have a full scale numerical towing tank in operation within the next few years. This ambitious plan can be divided into several building blocks, like developing method to calculate open water performance and the implementation of the cavitation model. In this paper two building...
In cities, flood waves may propagate over street surfaces below which lie complicated pipe networks used for storm drainage and sewage. The flood and pipe flows can interact at connections between the underground pipes and the street surface. The present paper examines this interaction, using the shallow water equations to model the flood wave hydrodynamics. Sources and sinks in the mass conservation equation are used to model the pipe inflow and outflow conditions at bed connections. We consider the problem reduced to one dimension. The shallow water equations are solved using a Godunov-type...
Aerodynamically induced car body vibrations of high-speed trains inside tunnels have for approximately two decades been recognized as a problem in Japan, while other nations’ high-speed rail services have not reported similar problems. In order to shed light on this contradiction the scope of the present paper is to primarily explore tail car vibrations of Deutsche Bahn AG’s high-speed train ICE 2 and Japan Railways series 300 Shinkansen train. Despite similarities of these two trains the problems are reported only for the latter. Several large eddy simulations are carried out to predict the...
The work investigates the pressure waves behavior in a cavity, the way that the treatment with Finite Volumes Method can be understood, aiming future studies like pressure waves in air intake system of an internal combustion engine. Using a CFD code it is possible to analyze more complex systems, including three dimensional effects. In most of cases, the problem is solved using analytical methods or one-dimensional numerical method. In the present work, the governing equations was discretized by Finite Volumes Method with an explicit formulation, and the time integration was made using the...
Vertical-axis wind turbines (VAWTs) have been shown to be useful machines to extract energy from the wind. It allows a large scale of power energy which can be extracted from small scale applications through to large scale electricity production. The present study concerns small scale applications. Some inventors discovered this kind of turbine in the same time on different places (in France, in Australia…) these last ten years. This paper concerns an industrial one used to light publicity panel but it can be also used to light small areas like parking, roads or for water pumping for example...
In water supply installations, noise pollution often occurs. As a basic component of a system, a flush valve may frequently be a source of noise and vibration, of which cavitation can be the problem, especially during valve closing or valve opening. The aim of this paper is to show how a numerical industrial code can point out a cavitation problem even if this code doesn’t use a cavitation model. This approach shows a good agreement with one using a cavitation model. The numerically obtained contours of the volume fraction of water vapour show cavitation inception distribution behind the...
Distributions in reactant species concentration in a PEMFC cause distributions in local current density, temperature and water over the area of a PEMFC. These can lead to effects such as flooding or drying of the membrane and cause stresses in different regions of the fuel cell. Changing flow-field configuration, including channel path length, width, or height to distribute the gas more evenly, is one method of minimizing these stresses. This work numerically investigated how serpentine flow-fields with different channel/rib's cross section areas affect performance and species distributions...
The discovery and archaeological excavation of the “Nossa Senhora dos Martires” wreck in the Tagus river between 1996 and 2001 renewed the interest in studying the ships (naus) that were used for transporting people and goods between Portugal and India in 16th and 17th centuries. A reconstruction of the hull, including above waterline structures, of the masts, yards and sail plan was carried out using the archaeological data, contemporary documents and iconography. In the present paper, the aerodynamics of the sails of the nau is numerically simulated. The reconstructed model of the nau is...

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