Documents published in Scipedia

• A Study on Seven-bladed Propeller for High-speed Ships by CFD

  Y. Okada, M. Okazaki, A. Okazaki, A. Boedimanand, K. Tamura

  marine2023.

  
  

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• Assessment of Emission Reduction and Fuel Savings using Ship Speed Optimization in Realistic Weather Conditions

  B. Taskar, K. Sasmal, L. Yiew

  marine2023.

  
  

  Abstract

  In this work, our objective is to quantify emission reductions using speed optimization considering a realistic ship route and a broad range of weather conditions. Two representative bulk carriers have been selected for the analysis. An optimization algorithm has been used to minimize voyage fuel consumption while completing the voyage on or before the expected arrival time. A constraint on engine power has been used for realistic estimates of achievable ship speeds in different weather conditions considering the available engine power. Multiple voyages at different ship speeds and in different seasons have been simulated with and without speed optimization to observe the effect of these factors on emission reduction. The effect of wind and waves on engine power has been considered by calculating wind and wave resistance along with propeller efficiency as a function of advance coefficients. Up to 11% reduction in fuel consumption was obtained by optimizing speed as compared to the constant speed profile. It was observed that a significant amount of fuel could be saved especially in seasons with a higher likelihood of heavy weather. Variation in fuel savings in different seasons has been discussed in the context of metocean conditions experienced in the selected months. Additionally, higher fuel savings were obtained for lower average ship speed which means speed reduction combined with speed optimization has greater potential to reduce emissions. Realistic estimates of fuel savings in a range of operating conditions presented in this paper would help ship owners, operators, and policymakers to assess the benefits of speed optimization among other technologies to decarbonize the shipping industry.

  Abstract
  In this work, our objective is to quantify emission reductions using speed optimization considering a realistic ship route and a broad range of weather conditions. Two representative [...]

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• System Modelling and Design Optimization of Wind Sails Under Different Sea and Wind Conditions

  C. Guzelbulut, K. Suzuki

  marine2023.

  
  

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• Large scale 3D Lattice Boltzmann method for coastal flows: Schematic case of the Eastern English Channel

  H. Smaoui, S. Kaidi

  marine2023.

  
  

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• Steps Towards the Direct Simulation of Submerged Canopy Flows

  P. Schmitt

  marine2023.

  
  

  • 3
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• Towards Reliable Performance Predictions for Stommel's Perpetual Salt Fountain

  J. Kemper, J. Mense, K. Graf, U. Riebesell, J. Kröger

  marine2023.

  
  

  Abstract

  Artificial Upwelling (AU) of nutrient-rich Deep Ocean Water (DOW) to the ocean’s sunlit surface layer is currently being investigated as a way of increasing the ecosystem productivity and enhancing the natural CO2 uptake of the ocean. AU is thus considered a marine Carbon Dioxide Removal (CDR) option (GESAMP, 2019) in addition to its potential in the context of open ocean fish and macroalgae farming (Kirke, 2003; Wu et al., 2023). A promising technical concept for AU was described by the oceanographer Stommel et al. (1956). Stommel proposed that the counteracting effects of typical open ocean temperature and salinity depth profiles on density can be utilized to drive a self-sustaining upwelling flow in a vertical ocean pipe. He termed this effect the ”perpetual salt fountain”. Despite several research efforts, none of the previous studies were able to reliably predict or demonstrate the potential of Stommel Upwelling Pipes (SUP)s. The growing interest in AU in light of current CDR research poses the need for reliable performance prediction methods and further development of Stommel’s concept. To fill this gap, two models have been developed in the present work. A Reynolds-Averaged Navier-Stokes (RANS) model and a one-dimensional numerical model. While the RANS model enables detailed modeling of the heat transfer and flow phenomena, the onedimensional numerical model allows for fast evaluation of simplified geometries for optimization and large-scale studies. This twofold approach allows for effective performance predictions while ensuring good reliability of the results. The present work shows the results of a number of studies, performed for different geometries and environmental conditions. The results of both models are compared and analyzed, and the respective potential is demonstrated. The presented results provide insight into some key aspects of the performance of SUPs and their potential for AU.

  Abstract
  Artificial Upwelling (AU) of nutrient-rich Deep Ocean Water (DOW) to the ocean’s sunlit surface layer is currently being investigated as a way of increasing the ecosystem [...]

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• Multi-Scale Euler-Lagrange Approach to Assess Cavitation Erosion in Hydrodynamic Flows

  A. Peters, U. Lantermann, O. el Moctar

  marine2023.

  
  

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• Numerical Investigation of Cavitation Bubble Dynamics Between Oblique Plates

  H. Sagar, O. el Moctar

  marine2023.

  
  

  • 3
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• Numerical Study of Cavitation on a Ship Propeller in Regular Waves of Different Headings

  K. Shin, H. Mikkelsen, Y. Shao, J. Walther, J. Nielsen

  marine2023.

  
  

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• Numerical Study of Ultrasound-Driven Bubble Collapse and Solid Deformation

  G. Son, J. Park

  marine2023.

  
  

  Abstract

  As ships operate under sea wave conditions most of time, it is desirable to consider the wave effect on propeller performance and cavitation safety in the propeller design process. In this work, unsteady cavitation simulations are carried out on a five-bladed propeller of KRISO container ship in calm water and regular waves of five different headings. Bare-hull simulations are made for estimating nominal hull wake fields by URANS solver. Cavitation simulations are made on the propeller and rudder by DES with a cavitation model and an Eulerian multiphase flow model. Nominal hull wake is numerically modelled in cavitation simulations as a propeller inflow instead of including a hull model. The maximum cavity area on the suction side of the blade is increased by 19 – 32% for beam, stern-quartering and following sea waves compared to calm water mostly due to the stronger axial hull wake. As the sheet cavity is more extended, tip vortex cavitation is intensified especially for stern-quartering and following waves. The maximum cavity area is on a similar level with less than 3% differences for head and bow waves as for calm water. The CFD investigation shows that hull wake differs depending on the wave direction and it can lead to significant changes in cavitation safety. 

  Abstract
  As ships operate under sea wave conditions most of time, it is desirable to consider the wave effect on propeller performance and cavitation safety in the propeller design [...]

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