Parametric Evaluation of Forces Due to a Passing Ship on a Moored Ship Using CFD Simulation

2021 ◽  
Author(s):  
Sreedevi Radhakrishnan ◽  
S. Nallayarasu
Keyword(s):  
Cfd Simulation ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Past Research ◽  
Inviscid Flow ◽  
Shipping Industry ◽  
Ship Traffic ◽  
Spacing Ratio ◽  
Parametric Studies ◽  
Computational Fluid Dynamics Cfd

Abstract Over the years, with advancements in the shipping industry, there has been considerable increase in size, numbers and speed of ships. Ports and harbours have to handle these larger ships and increased ship traffic within the limited space especially in matured ports. Due to the above mentioned issues at the ports and harbours, passing ship interactions with a moored ship is eventual. Pressure variations around the passing ship may cause additional forces and moments on the ship moored in the vicinity. Though there is literature from past research available on the subject, only few parameters have been investigated. The passing ship forces on a moored ship has been evaluated using Computational Fluid Dynamics (CFD), based on a double-body flow model. Simulations were carried out for three-dimensional, unsteady, inviscid flow using overset meshing technique to facilitate the movement of the vessel. The results obtained from CFD simulations were compared with the existing results obtained by experiments (Remery, 1974) for the validation of the CFD model. Detailed parametric studies were carried out for parameters such as velocity ratio and displacement ratio, spacing ratio, and water depth ratio. Empirical equations for force and moment coefficients are derived based on the present study and recommendations for passing vessel distances from moored vessel has been made in the article.

CFD SIMULATION OF SHEAR STRESS AND SECONDARY FLOWS IN URETHRA

2007 ◽  
Vol 19 (02) ◽  
pp. 117-127 ◽  
Author(s):  
Yang-Yao Niu ◽  
Ding-Yu Chang
Keyword(s):  
Shear Stress ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Normal Female ◽  
Urinary System ◽  
Stress Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Peak Value ◽  
Lower Urinary

In this work, a preliminary numerical simulation of the lower urinary system using Computational Fluid Dynamics (CFD) is performed. Very few studies have been done on the simulation of three-dimensional urine through the lower urinary system. In this study, a simplified lower urinary model with rigid body assumption is proposed. The distributions of urine flow velocity, wall pressure and shear stress along the urethra are simulated based on MRI scanned uroflowmetry of a normal female. Numerical results show that violent secondary flows appear on the cross surface near the end of the urethra when the inflow rate is increased. The oscillative variation of pressure and shear stress distributions are found around the beginning section of the urethra when flow rate is at the peak value.

scholarly journals Study on Mechanism of Series-Flow of Pollutants between Consecutive Tunnels by Numerical Simulation

2019 ◽  
Vol 9 (19) ◽  
pp. 4125
Author(s):  
Honghu Zhang ◽  
Yunge Hou ◽  
Kaijie Wu ◽  
Tianhang Zhang ◽  
Ke Wu ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Wall Jet ◽  
Air Velocity ◽  
Pressure Area ◽  
Computational Fluid Dynamics Cfd ◽  
Jet Theory ◽  
Jet Characteristics ◽  
Tunnel Entrance

The characteristics of series-flow between two consecutive tunnels with distance ranging from 20 m to 250 m are explored by computational fluid dynamics (CFD) parametric simulations of structure and operation parameters. The research indicates that series-flow can be considered the three-dimensional wall jet diffusion of upstream tunnel pollutants under the effects of the negative pressure area of the downstream tunnel entrance. The jet characteristics are primarily related to the tunnel distance between upstream and downstream tunnels and hydraulic diameters, and only influenced by the negative pressure in the area very close to downstream entrance where the tunnel air velocity ratio, i.e., the velocity of upstream tunnel air divided by the velocity of downstream tunnel air, decides the degree of the influence. If ignoring the effects of ambient wind and traffic flow, the series-flow ratio decreases with the increasing of parameters of the normalized tunnel distance, i.e., the tunnel distance divided by tunnel hydraulic diameter, and the tunnel air velocity ratio. Based on the three-dimensional wall jet theory, a series-flow model covering all jet characteristic sections is built. The experiment results indicate that the model applies to consecutive tunnels with any spacing and exhibits higher prediction accuracy.

The simulation of single wraparound fin on a semi-cylindrical missile body

2020 ◽  
Vol 92 (3) ◽  
pp. 418-427 ◽  
Author(s):  
Nayhel Sharma ◽  
Rakesh Kumar
Keyword(s):  
Research Study ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Future Research ◽  
Aerodynamic Coefficients ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Predicted Values ◽  
Characteristic Trend ◽  
Practical Implications

Purpose The purpose of this paper is to establish a freestream computational fluid dynamics (CFD) model of a three-dimensional non-spinning semi-cylindrical missile model with a single wrap around fin in Mach 2.70-3.00M range and 0° angle of attack, and ultimately establishing itself for future research study. Design/methodology/approach In this study, the behaviour of flow around the fin was investigated using a κ-ϵ turbulence model of second-order of discretization. This was done using a highly structured mesh. Additionally, an inviscid CFD simulation involving the same boundary conditions have also been carried out for comparison. Findings The obtained values of aerodynamic coefficients and pressure contours visualizations are compared against their experimental and computational counterparts. A typical missile aerodynamic characteristic trend can be seen in the current CFD. Practical implications The predicted values of the aerodynamic coefficients of this single fin model have also been compared to those of the full missile body comprising of four fins from the previous research studies, and a similar aerodynamic trend can be seen. Originality/value This study explores the possibility of the use of turbulence modelling in a single fin model of a missile and provides a basic computational model for further understanding the flow behaviour near the fin.

Transient CFD Visualization of Fossil Fuel Combustion Simulations

2003 ◽  
Author(s):  
Brian Dotson ◽  
Kent Eshenberg ◽  
Chris Guenther ◽  
Thomas O’Brien
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Cfd Simulation ◽  
Low Cost ◽  
Three Dimensional ◽  
Cfd Simulations ◽  
Projection System ◽  
Computational Fluid Dynamics Cfd ◽  
High Level ◽  
Wall System

The design of high-efficiency lower-emission coal-fed power plants is facilitated by the extensive use of computational fluid dynamics (CFD) simulations. This paper describes work conducted at the National Energy Technology Laboratory (NETL) and Pittsburgh Supercomputing Center (PSC) to provide an environment for the immersive three-dimensional visualization of CFD simulation results. A low-cost high-resolution projection system has been developed in the visualization lab at NETL. This multi-wall system consists of four projection screens, three of which are tiled into four quadrants. The graphics for the multi-wall system are rendered using a cluster of eight personal computers. A high-level visualization interface named Mavis has also been developed to combine the powerful 3D modules of OpenDX with methods developed at NETL for studying multiphase CFD data. With Python, a completely new OpenDX user interface was built that extends and simplifies the features of a basic graphics library.

scholarly journals Numerical Analysis of Blood Flow Through Discrete Stenosis: Role of Eccentricity and Spacing Ratio

2017 ◽  
Author(s):  
Siyeong Ju ◽  
Linxia Gu
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Recirculation Zone ◽  
Cfd Simulation ◽  
Flow Region ◽  
Flow Recirculation ◽  
Spacing Ratio ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Interference

Stenosis or narrowing of arteries induces a turbulent flow region downstream. Multiple stenosis may lead to flow interference and further disturb the blood flow. This has important clinical implications [1], such as disturbed blood flow and flow recirculation which were correlated with the development of atherosclerosis by upregulating the endothelial cells genes and proteins that cause atherogenesis [2]. Numerical simulation of concentric stenoses by Lee et al [3] have shown that the recirculation zone following the first concentric stenosis affected the flow field at the downstream of the second one, which was dependent on the spacing ratio and degree of stenosis. However, the majority of stenosis is eccentric [2] and the detailed fluid dynamics of multiple stenoses with eccentric constrictions is lacking. The aim of this study is to investigate the interactions between double stenoses with eccentricity using computational fluid dynamics (CFD) simulation. The role of spacing ratio on the recirculation zone and turbulence intensity (TI) were characterized and also compared to concentric cases.

Numerical Analysis of Flow Behavior Inside the Blast Furnace

2009 ◽  
Author(s):  
Dong Fu ◽  
Fengguo Tian ◽  
Guoheng Chen ◽  
D. Frank Huang ◽  
Chenn Q. Zhou
Keyword(s):  
Blast Furnace ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Furnace Productivity ◽  
Gas Distribution ◽  
Furnace Shaft ◽  
Parametric Studies ◽  
Flow Through

Gas and burden distributions inside a blast furnace play an important role in optimizing gas utilization versus the furnace productivity and minimizing the CO2 emission in steel industries. In this paper, a mathematical model is presented to describe the burden descent in the blast furnace shaft and gas distribution, with the alternative structure of coke and ore layers being considered. Multi-dimensional Ergun’s equation is solved with considering the turbulent compressible gas flow through the burden column. The porosity of each material will be treated as a function of three dimensional functions which will be determined by the kinetics sub-models accordingly. A detailed investigation of gas flow through the blast furnace will be conducted with the given initial burden profiles along with the effects of redistribution during burden descending. Also, parametric studies will be carried out to analyze the gas distribution cross the blast furnace under different cohesive zone (CZ) shapes, charging rate, and furnace top pressure. A good agreement was obtained between the CFD simulation and published experimental data. Based on the results, the inverse V shape is proved to be the most desirable CZ profile.

Optimization of CFD Meshing for Stented Vessel Geometries

2014 ◽  
Vol 553 ◽  
pp. 373-378 ◽  
Author(s):  
Azadeh Lotfi ◽  
Tracie J. Barber
Keyword(s):  
Cfd Simulation ◽  
Computational Cost ◽  
Three Dimensional ◽  
Coronary Bifurcation ◽  
Cfd Simulations ◽  
Coronary Stent Implantation ◽  
Bifurcation Stenting ◽  
Computational Fluid Dynamics Cfd ◽  
Blood Flow Patterns ◽  
High Computational Cost

Coronary stent implantation is the most widely used technique currently employed to treat atherosclerosis in coronary artery. Although the optimal technique for bifurcation stenting in terms of clinical outcome is still open to controversy, most previous studies have focused on the single-stenting techniques due to its simpler geometry and easier clinical implantation. While the biomedical environment in a stented coronary bifurcation is extremely challenging to model, Computational Fluid Dynamics (CFD) investigations have been used to study the effect of stent on blood flow patterns, however, in CFD simulation of double-stenting techniques, the presence of two or more stents accentuates the complexity of the geometry and the associated meshes especially in the region where two or multiple stent layers come together. Hence, in this study, complex three-dimensional geometric CFD simulations of a stented vessel have been performed in order to adopt an efficient and optimal meshing method to reduce the high computational cost. In doing so, several meshing strategies were chosen and applied.

scholarly journals CFD Simulation of Knock Onset in a Heavy-Duty Spark Ignition Gas Engine

2019 ◽  
Vol 8 (4) ◽  
pp. 9585-9593
Keyword(s):  
Fluid Dynamics ◽  
Numerical Model ◽  
Cfd Simulation ◽  
Combustion Process ◽  
Three Dimensional ◽  
Spark Ignition ◽  
Heavy Duty ◽  
Gas Engine ◽  
Optimization Study ◽  
Computational Fluid Dynamics Cfd

The paper describes a method for evaluating knocking onset with computational fluid dynamics (CFD) numerical model of the combustion process of spark ignited (SI) gas engine and methods for assessing the probability of knocking combustion based on this model. The probability of knocking combustion, which characterizes the boundary condition between normal combustion and knocking, is determined (8%). An optimization study of the influence of adjustment parameters on the probability of knocking based on a three-dimensional numerical model is carried out. The developed and tested technique allows one to monitor the tendency of the influence of various adjustment parameters on the probability of knocking in a SI gas engine.

scholarly journals Numerical Research on the Vortex Center on the Forward-Swept 3-D Wind Turbine Blades at Low Rotational Speed

2018 ◽  
Vol 12 (12) ◽  
pp. 80
Author(s):  
Sutrisno . ◽  
Setyawan Bekti Wibowo ◽  
Sigit Iswahyudi
Keyword(s):  
Wind Turbine ◽  
Rotational Speed ◽  
Cfd Simulation ◽  
Velocity Ratio ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Leading Edge ◽  
Vortex Center ◽  
Wind Turbine Blades ◽  
Horizontal Axis Wind Turbine

This paper studies the CFD simulation of forward three-dimensional (3-D) horizontal axis wind turbine (HAWT) blades. Using logarithmic grid and Q-criterion to learn the vortex dynamics around the blades at low rotational speed. The computational fluid dynamics (CFD) simulation uses Q-criterion to probe vortices and logarithmic grid to emphasize the micro-gridding effect of the turbulent boundary layer. The visualization & measurement of the simulation results give the coefficient of pressure (Cp). For forward 3-D wind turbine blade, at low rotational speed, the strongly accelerated laminar region surrounds the lower blade, and the decelerated tip blade region coalesce each other give rise to a reverse limiting streamline, eroding the laminar region further until a little is left on the tip of the blade. The "reverse limiting streamline" grows inward radially, the area is narrowing closing to the leading edge of the blade tip. The second side of the rolled-up vortex appears the velocity ratio (Uc/Ulocal) of the second vortices are higher than the main vortex cores. For radius R=1.547 m, U=12 m/s, at 210 RPM, CL and CD values reach a maximum with fully laminar tip conditions. While at 120 RPM, the CL and CD values reach a minimum in the absence of laminar tips. The results show the detailed vortex dynamic pattern surround the blades, give more understanding to design laminar 3-D blade toward a noiseless wind turbine system.

Compressing Aerodynamic Hazard Data

2022 ◽  
Author(s):  
Yang Zhou ◽  
Nicolas Boullé ◽  
David Barton ◽  
Eduard Campillo-Funollet ◽  
Cameron Hall
Keyword(s):  
Cfd Simulation ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Data Streaming ◽  
Compression Method ◽  
Simulation Data ◽  
Geometrical Features ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Compression ◽  
And Control

Data compression of three-dimensional computational fluid dynamics (CFD) simulation data is crucial to allow effective data-streaming for drone navigation and control. This problem is computationally challenging due to the complexity of the geometrical features present in the CFD data, and cannot be tackled by standard compression techniques such as sphere-tree. In this report, we present two different methods based on octree and cuboid primitives to compress velocity isosurfaces and volumetric data in three dimensions. Our volume compression method achieves a 1400 compression rate of raw simulation data and allows parallel computing.

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