scholarly journals Hydrodynamic study of the influence of bulbous bow design for an Offshore Patrol Vessel using Computational Fluid Dynamics

2018 ◽  
Vol 11 (22) ◽  
pp. 29
Author(s):  
Luis Leal ◽  
Edison Flores ◽  
David Fuentes ◽  
Bharat Verma
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Hydrodynamic Performance ◽  
Design Stage ◽  
Hull Form ◽  
Preliminary Design Stage ◽  
Hydrodynamic Study ◽  
Resistance Curves ◽  
Design Speed ◽  
Bulbous Bow

The resistance of a ship is of vital importance in giving greater viability to the development of a design project, since at lower ship resistance, the power demand to achieve a desired design speed will be lower which will reduce the amount of power to be installed in the ship resulting in lower fuel consumption. The use of computational fluid dynamics to analyze and optimize hull form and its appendages permits the hydrodynamic performance of the ship to be improved from the early design stages, allowing improvements to the hull shape and appendages. This paper shows a qualitative analysis which was performed to reduce the resistance of the OPVMKII (Second Generation Offshore Patrol Vessel) in its preliminary design stage by means of designing and integrating three types of bulbous bow with the ship´s hull and analyzing the resistance curves obtained using computational fluid dynamics.

scholarly journals Hydrodynamic performance analysis of a shore fixed oscillating water column wave energy converter in the presence of bottom variations

2019 ◽  
Vol 234 (1) ◽  
pp. 37-47
Author(s):  
Piyush Mohapatra ◽  
Trilochan Sahoo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Column ◽  
Boundary Integral ◽  
Hydrodynamic Performance ◽  
Design Stage ◽  
Pressure Jump ◽  
Front Wall ◽  
Oscillating Water Column ◽  
Sea Bed

In this study, the effect of the stepped sea bed on the hydrodynamic performance of an oscillating water column device is investigated using computational fluid dynamics . This investigation is performed in a numerical wave tank modeled using ANSYS Fluent, which incorporates a transient, multiphase volume of fluid method to track the air–water interface. The power take-off unit is modeled as a porous zone in the flow field to produce the pressure jump versus flow characteristics that of a real air turbine. The efficiency of the chamber with and without the stepped bottom is analyzed and compared with known results in the literature. The flow parameters such as the temporal evolution and distribution of the pressure field, velocity field and free surface are studied to understand the performance of the proposed model. The study reveals that there is an improvement in hydrodynamic efficiency with the inclusion of the stepped bottom beneath the oscillating water column chamber, which is in agreement with the previous studies carried out using analytical and boundary integral equation methods. Moreover, the computational fluid dynamics model helps to understand the flow dynamics inside the oscillating water column chamber in a more intricate manner compared to the potential flow-based studies pursued in the literature. The formation of vortices within the oscillating water column chamber, near the front wall and stepped bottom could be captured, which affects the chamber performance to a certain extent. Overall, the study could be useful in the initial design stage of shore fixed oscillating water column devices.

Hydrodynamic Optimization of a Wedge Hull

2015 ◽  
Author(s):  
Lijue Wang ◽  
Fuxin Huang ◽  
Chi Yang ◽  
Raju Datla
Keyword(s):  
Hydrodynamic Performance ◽  
Surface Mesh ◽  
Nurbs Surface ◽  
Bottom Edge ◽  
Hull Form ◽  
Entrance Angle ◽  
Total Drag ◽  
Rounded Corner ◽  
Bulbous Bow ◽  
Hydrodynamic Optimization

A novel wedge-shaped hull form is optimized for reduced drag using a further developed practical hydrodynamic optimization tool. The hull features a sharp entrance angle, rectilinear sides, sharp bottom edges, a triangular waterplane and a linear aftward taper from a deep bow to a shallow transom. The optimization involves two modifications of the hull form, one is to smooth out the sharp bottom edge with a rounded corner and the other is to generate a bulbous bow. In order to perform the hydrodynamic optimization of the hull, a Non-Uniform Rational BSpline (NURBS)-based hull surface modification tool, a NURBS surface mesh generator, a surrogate model and an evolutionary optimization solver are developed and integrated into the practical hydrodynamic optimization tool. The hydrodynamic performances, i.e., the total drag and the flow field near the obtained hull bodies are assessed and compared with the original wedge hull using numerical simulations. Results showed that rounding the sharp edge of the wedge hull can reduce the total drag by alleviating the flow separations around the hull body. The wedge hull with rounded bottom edge and optimized bulbous bow can achieve larger drag reduction and the flow separations are almost eliminated. The total drag of the optimal hull is compared with an earlier-optimized wedge hull that has a different type of bulbous bow, whose hydrodynamic performance has been validated by model tests.

An Approximate Method for Cross Curves of Cargo Vessels

2001 ◽  
Vol 38 (02) ◽  
pp. 92-94
Author(s):  
Huseyin Yilmaz ◽  
Mesut Giiner
Keyword(s):  
Prediction Method ◽  
Design Stage ◽  
Series Data ◽  
Design Parameters ◽  
Preliminary Design ◽  
Hull Form ◽  
Beam Depth ◽  
Preliminary Design Stage ◽  
The Mathematical Model ◽  
Load Conditions

In this study, a formula is presented to estimate cross curves of cargo vessels and to predict statical stability at the preliminary design stage of the vessel. The predictive technique is obtained by regression analysis of systematically varied cargo vessel series data. In order to achieve this procedure, some cargo vessel forms are generated using Series-60. The mathematical model in this predictive technique is constructed as a function of design parameters such as length, beam, depth, draft, and block coefficient. The prediction method developed in this work can also be used to determine the effect of specific hull form parameters and the load conditions on stability of cargo vessels. The present method is applied to a cargo vessel and then the results of the actual ship are compared with those of regression values.

scholarly journals Computational fluid dynamics simulation as a tool for optimizing the hydrodynamic performance of membrane bioreactors

RSC Advances ◽  
2019 ◽  
Vol 9 (55) ◽  
pp. 32034-32046 ◽  
Author(s):  
Yan Jin ◽  
Cheng-Lin Liu ◽  
Xing-Fu Song ◽  
Jian-Guo Yu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Membrane Bioreactors ◽  
Dynamics Simulation ◽  
Hydrodynamic Performance ◽  
Shear Stresses ◽  
Computational Fluid Dynamics Simulation ◽  
Hydrodynamic Properties

The hydrodynamic properties and shear stresses experienced by a membrane bioreactor (MBR) are directly related to its rate of membrane fouling.

scholarly journals Nurbs modeling for design waterline based on the variation of sectional area curve

2021 ◽  
Vol 3 (SI2) ◽  
pp. SI37-SI46
Author(s):  
Hoa Thị Ngọc Nguyễn ◽  
Ngoc Bich Vu ◽  
Tat-Hien Le
Keyword(s):  
Mathematical Model ◽  
Quadratic Function ◽  
Design Stage ◽  
Sectional Area ◽  
Hull Form ◽  
B Spline ◽  
Preliminary Design Stage ◽  
Form Design ◽  
Hull Form Design ◽  
The Mathematical Model

Hull form design from parent ships transforms the ship's parameters based on the variation of theoretical sectional area curve of the Lackenby method. The correction and modification of the theoretical sectional area curve is essentially the change of ship displacement, hull form coefficients, and the longitudinal center of buoyancy from the parent ships. In the preliminary design stage, the hull form design approach from parent ships minimizes the risks compared to the new design while still retaining hydrostatic and hydrodynamics' advantages. However, the Lackenby method of ship hull form variation uses a linear or quadratic function to shift the sectional area curves, regardless of the ship's hull form faring, especially the curvature's discontinuity the bow, stern, and midship. Therefore, the computer graphic algorithm based on the B-spline function is studied and applied; simultaneously, the mathematical model for the designed waterline is built in the form of a continuous curve instead of the B-spline segments. In this study, the mathematical model for the coastal container ship's design water line is constructed, ensuring continuity and fairing throughout the continuous B-spline curve. The geometry continuity evaluation results are expressed through the parameter curve's curvature and resistance component calculations' performance by computational analysis.

Performance of a Shore Fixed Oscillating Water Column Device for Different Bottom Slopes and Front Wall Drafts: A Study Based on Computational Fluid Dynamics and BIEM

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Piyush Mohapatra ◽  
K. G. Vijay ◽  
Anirban Bhattacharyya ◽  
Trilochan Sahoo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Column ◽  
Wave Energy ◽  
High Efficiency ◽  
Boundary Integral ◽  
Hydrodynamic Performance ◽  
Chamber Pressure ◽  
Front Wall ◽  
Oscillating Water Column

Abstract Oscillating water column (OWC) wave energy converters are one of the most widely researched devices for ocean wave energy harvesting. This study investigates the hydrodynamic performance of a shore-fixed OWC device for different bottom slopes using two numerical approaches, namely, computational fluid dynamics (CFD) and boundary integral equation method (BIEM). In the BIEM method, the boundary value problem is solved in two-dimensional Cartesian coordinates using the linear water wave theory. The CFD model uses a numerical wave tank (NWT) built using the volume of fluid (VOF) method. Numerical computations are carried out for different sloped bottom geometries and front wall drafts to analyze the hydrodynamic efficiency. There is a general agreement between CFD and BIEM results in terms of resonating behavior of the device. It is observed that the front wall draft has a more significant effect, a lower draft leading to a wider frequency band for optimum conversion at high efficiency. While the BIEM-based analysis resulted in improved performance curve for few of the steeper slopes, the CFD study predicted a lower peak efficiency for the same slopes due to the consideration of real fluid characteristics. Detailed performance comparisons are presented using the time histories of free surface elevation, chamber pressure, and streamlines at different time instants within the OWC chamber.

Hull form design of underwater vehicle applying CFD (Computational Fluid Dynamics)

2010 ◽  
Author(s):  
Tomoya Inoue ◽  
Hiroyoshi Suzuki ◽  
Risa Kitamoto ◽  
Yoshitaka Watanabe ◽  
Hiroshi Yoshida
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Underwater Vehicle ◽  
Hull Form ◽  
Form Design ◽  
Hull Form Design

Investigation of the flow in a small-scale turbocharger centrifugal compressor

2016 ◽  
Vol 231 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Hamid R Hazby ◽  
Liping Xu ◽  
Michael V Casey
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Centrifugal Compressor ◽  
Numerical Study ◽  
Optical Measurements ◽  
Small Scale ◽  
Flow Features ◽  
Design Speed ◽  
And Performance ◽  
Compressor Map

This paper presents an experimental and numerical study of the flow in a 1:1 scale, automotive turbocharger centrifugal compressor. Particle image velocimetry measurements have been carried out in the vaneless diffuser at 50% of the design speed. The challenges involved in taking optical measurements in the current small-scale compressor rig are discussed. The overall stage performance and the measured diffuser flow are compared with the results of steady-state computational fluid dynamics calculations. A good agreement between the computational fluid dynamics and the experimental results demonstrates that the numerical methods are capable of predicting the main flow features within the compressor. The synthesis of measured and predicted data is used to explain the sources of the flow and performance variations across the compressor map, and the differences in loss production between small and large compressors are highlighted.

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