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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