Capturing Dynamic Effects in Ship Tanks - A coupling between HydroD™ and OpenFOAM®

Examensarbete för masterexamen

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Type: Examensarbete för masterexamen
Master Thesis
Title: Capturing Dynamic Effects in Ship Tanks - A coupling between HydroD™ and OpenFOAM®
Authors: Andersson, Jacqueline
Pedersen, Jonas
Abstract: When a ship with partially filled tanks is subjected to waves with frequencies in the vicinity of the natural period of the fluid inside the tanks, sloshing occurs. Sloshing influences the seakeeping properties of a ship but can be hard to capture when using softwares in seakeeping. DNVs software HydroD has this problem and cannot capture the dynamic forces from the tank, as it is today. The dynamic forces can be captured by using CFD and that is why a coupling between HydroD and a CFD software is interesting to investigate. By using already existing CFD software, that is able to give these dynamic forces as a force input, the problem might get solved. If choosing OpenFOAM which has the advantage of being easy available and free, it could also be beneficial from an economical point of view, since it would cost DNV more to develop a CFD feature in HydroD than using this software. The idea was to run HydroD initially to get a motion output from a barge model that would be used as motion input for the tank simulated in OpenFOAM. In turn, OpenFOAM would output forces to be used as force input in HydroD. This data exchange between the two programs would make an iterative process that would go on until the motion in HydroD converged. When investigating this problem, the results were verified against a known experiment where a model of a barge with a tank was subjected to beam sea and free to move in sway, heave and roll. Two particular cases were studied, one where the tank had no free surface effect and could be considered “closed”, and one where the tank was partially filled having a free surface. For the case without any free surface, results agreed well with the experimental one but for the case where there was a free surface present, the results were not as satisfying. Still, these results gave an indication that it could be possible to use OpenFOAM together with HydroD, but unfortunately time was a restricting factor which is why further work will be needed for obtaining better agreement, as described in recommendations.
Keywords: Transport;Farkostteknik;Transport;Vehicle Engineering
Issue Date: 2011
Publisher: Chalmers tekniska högskola / Institutionen för sjöfart och marin teknik
Chalmers University of Technology / Department of Shipping and Marine Technology
Series/Report no.: Report. X - Department of Shipping and Marine Technology, Chalmers University of Technology, Göteborg, Sweden : 259
Collection:Examensarbeten för masterexamen // Master Theses

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