MSGID: 1:317/3 640960ff   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Flat plate bow covers pave way for more economical shipping by improving   
   ship aerodynamics    
    Computational fluid dynamics simulations reveal that flat plate bow   
   covers can decrease up to 42% of the wind drag on the hull of ships    
      
     Date:   
         March 8, 2023   
     Source:   
         Shibaura Institute of Technology   
     Summary:   
         Ships are the main modes of transport for global trade as they   
         are efficient and effective. Improving the aerodynamic performance   
         of ship could reduce fuel consumption and improve speed, further   
         improving the economics of shipping. Recently, researchers from   
         have demonstrated that flat plate bow covers on ships can reduce   
         overall wind drag in ships by nearly 40%, which could lead to   
         enormous fuel savings.   
      
      
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   FULL STORY   
   ==========================================================================   
   Ships are the main modes of transport for global trade as they are   
   efficient and effective. Improving the aerodynamic performance of ship   
   could reduce fuel consumption and improve speed, further improving the   
   economics of shipping.   
      
   Recently, researchers from Japan and Vietnam have demonstrated that flat   
   plate bow covers on ships can reduce overall wind drag in ships by nearly   
   40%, which could lead to enormous fuel savings.   
      
      
   ==========================================================================   
   Marine transportation accounts for over 80% of international trade. It   
   is facilitated by superstructures, such as passenger ships, container   
   ships, oil tankers, and roll-on-roll-off car ferries, making it efficient   
   and effective.   
      
   Nevertheless, there is an ever pressing need to make shipping more   
   economical.   
      
   In this regard, scientists have conducted numerous studies to improve   
   the aerodynamic performance of ships, which face significant drag force   
   from winds on their above-water hull -- the visible body of the ship --   
   when sailing.   
      
   Recently, an international cooperation research group -- comprising   
   Dr.Ngoc-Tam Bui, an Assistant Professor at the College of Systems   
   Engineering and Science at the Shibaura Institute of Technology and   
   Dr. Ngo Van He and Dr. Ngo Van Hien, Associate Professors from Hanoi   
   University of Science and Technology - - has simulated and compared   
   different bow (the front of the hull) covers, which reduce the total wind   
   drag acting on ships. Their work was made available online on 31 January   
   2023 and published in Volume 270 of the Ocean Engineering journal on 15   
   February 2023.   
      
   Prof. Bui briefly explains the research methodology. "This work utilized   
   ANSYS- Fluent, a commercial software, for performing computational   
   fluid dynamics (CFD) simulations. Herein, a small passenger ship   
   (with and without a bow cover) and its surroundings were divided   
   into millions of elements using a mesh -- a numerical grid. Then,   
   'Reynolds-averaged Navier-Stokes equations,' which represent time-averaged   
   fluid flow motion for each element, were solved using a turbulent   
   viscous model. Their combined results yielded the wind drag acting on   
   the ship's above-water hull."  The researchers found that a finer mesh   
   gave more accurate results, with 23.62 million elements as an optimum   
   number. In addition, a model called 'detached- eddy-simulation (DES)   
   k-e' yielded the lowest wind drag out of the five turbulent viscous   
   models tested in this work. Using the optimum mesh and DES k- e model,   
   the researchers performed CFD simulations for seven flat plate-shaped   
   bow covers of different lengths and heights, as well as a conventional   
   streamlined cover. "The dynamic pressure region around the bow and   
   the wind drag reduced drastically with increasing height of the flat   
   plate cover. The ship faced 38.71% lower total drag with a 2.4 m-high   
   bow cover than a 0.37 m- high one. This value is similar to the 42.41%   
   reduction for a ship with the streamlined cover," highlights Prof. Bui.   
      
   In this work, the researchers also highlight the effect of wind direction   
   on the aerodynamic performance of a ship. The drag is the highest,   
   irrespective of the bow cover when the wind blows at an angle of 20o to   
   the ship's direction.   
      
   Further, it is almost zero for 90o. At larger angles, the wind drag   
   reverses direction, aiding the ship's movement.   
      
   Discussing the future potential of the present work, Prof. Bui says, "The   
   proposed flat plate bow cover is simple to manufacture and reduces the   
   wind drag acting on a ship almost as well as a streamlined cover. Thus,   
   it will improve the aerodynamic performance of small passenger ships,   
   resulting in greater fuel oil savings and economic efficiency in marine   
   transportation."  The findings of this work could prove useful for ship   
   designers and engineers to optimize fuel consumption, thereby leading   
   to more economical shipping.   
      
       * RELATED_TOPICS   
             o Matter_&_Energy   
                   # Wind_Energy # Automotive_and_Transportation #   
                   Civil_Engineering # Energy_and_Resources   
             o Earth_&_Climate   
                   # Renewable_Energy # Energy_and_the_Environment #   
                   Environmental_Issues # Environmental_Science   
       * RELATED_TERMS   
             o Ethanol_fuel o Automotive_aerodynamics o Plastic o Radar o   
             Multistage_rocket o Concorde o Flexible-fuel_vehicle o Methane   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Shibaura_Institute_of_Technology. Note: Content may be edited for style   
   and length.   
      
      
   ==========================================================================   
   Related Multimedia:   
       * Illustration_of_aerodynamic_performance_of_ships_with_flat_plate_and   
         streamlined_bow_covers   
   ==========================================================================   
   Journal Reference:   
      1. Ngo Van He, Ngo Van Hien, Ngoc-Tam Bui. Analyis of aerodynamic   
         performance of passenger ship with different frontal accommodations   
         using CFD. Ocean Engineering, 2023; 270: 113622 DOI: 10.1016/   
         j.oceaneng.2023.113622   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/03/230308112207.htm   
      
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