Numerical Modeling of Berm Breakwater Optimization With Varying Berm Geometry Using REEF3D

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Athul Sasikumar ◽  
Arun Kamath ◽  
Onno Musch ◽  
Hans Bihs ◽  
Øivind A. Arntsen
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Flow Through Porous Media ◽  
Cfd Model ◽  
Production Chain ◽  
Offshore Production ◽  
Physical Model Tests ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through

Harbors are important infrastructures for an offshore production chain. These harbors are protected from the actions of sea by breakwaters to ensure safe loading, unloading of vessels and also to protect the infrastructure. In current literature, research regarding the design of these structures is majorly based on physical model tests. In this study a new tool, a three-dimensional (3D) numerical model is introduced. The open-source computational fluid dynamics (CFD) model REEF3D is used to study the design of berm breakwaters. The model uses the Volume-averaged Reynolds-averaged Navier-Stokes (VRANS) equations to solve the porous flows. At first, the VRANS approach in REEF3D is validated for flow through porous media. A dam break case is simulated and comparisons are made for the free surface both inside and outside the porous medium. The numerical model REEF3D is applied to show how to extend the database obtained with purely numerical results, simulating different structural alternatives for the berm in a berm breakwater. Different simulations are conducted with varying berm geometry. The influence of the berm geometry on the pore pressure and velocities are studied. The resulting optimal berm geometry is compared to the geometry according to empirical formulations.

Numerical Investigation of Wave Kinematics Inside Berm Breakwaters With Varying Berm Geometry Using REEF3D

2017 ◽  
Author(s):  
Athul Sasikumar ◽  
Hans Bihs ◽  
Arun Kamath ◽  
Onno Musch ◽  
Øivind A. Arntsen
Keyword(s):  
Numerical Model ◽  
Water Waves ◽  
Numerical Models ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Production Chain ◽  
Wave Kinematics ◽  
Offshore Production ◽  
Physical Model Tests ◽  
Hydrodynamic Processes

Harbours are important infrastructures for an offshore production chain. These harbours are protected from the actions of sea by breakwaters to ensure safe loading, unloading of vessels and also to protect the infrastructure. One of the important hydrodynamic processes in these regions is the interaction of water waves with permeable breakwaters such as rubble mound breakwaters or berm breakwaters. It is important to study the wave-breakwater interactions in order to have an optimal design of these structures. In current literature, research regarding the design of these structures is majorly based on physical model tests. Empirical formulations are derived based on these test, which can have a relatively narrow range of applicability. In this study a new tool, a three-dimensional numerical model is introduced. Physical and numerical models have limitations that can restrict their independent use. A combined use of both can lead to different forms of improvements: being able to model problems that cannot be modelled by either physical or numerical modelling alone; increasing quality at the same cost or obtaining the same quality at reduced cost. In this study, the open-source CFD model REEF3D is used to study the design of berm breakwaters. The model uses the Volume averaged Reynolds Averaged Navier-Stokes (VRANS) equations to solve the porous flows. At first the VRANS approach in REEF3D is validated for flow through porous media. A dam break case is simulated for two different porous materials. Comparisons are made for the free surface both inside and outside the porous medium. The numerical model REEF3D is applied to show how to extend the database obtained with purely numerical results, simulating different structural alternatives for the berm in a berm breakwater. Different simulations are conducted with varying berm geometry. The influence of the berm geometry on the pore pressure and velocities are studied. The resulting optimal berm geometry is compared to the geometry according to empirical formulations.

scholarly journals ICCM2015: A Comparison of RANS and LES Computational Methods in Analyzing Ventilation Flow Through a Room Fitted with a Two-Sided Windcatcher

2017 ◽  
Vol 14 (03) ◽  
pp. 1750021 ◽  
Author(s):  
A. Niktash ◽  
B. P. Huynh
Keyword(s):  
Natural Ventilation ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Interior Space ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Cfd Method ◽  
Good Agreement

A windcatcher is a structure for providing natural ventilation using wind power; it is usually fitted on the roof of a building to exhaust the inside stale air to the outside and supplies the outside fresh air into the building interior space working by pressure difference between outside and inside of the building. In this paper, the behavior of free wind flow through a three-dimensional room fitted with a centered position two-canal bottom shape windcatcher model is investigated numerically, using a commercial computational fluid dynamics (CFD) software package and LES (Large Eddy Simulation) CFD method. The results have been compared with the obtained results for the same model but using RANS (Reynolds Averaged Navier–Stokes) CFD method. The model with its surrounded space has been considered in both method. It is found that the achieved results for the model from LES method are in good agreement with RANS method’s results for the same model.

Development of a CFD Model to Simulate Three-Dimensional Gap Resonance Applicable to FLNG Side-by-Side Offloading

2017 ◽  
Author(s):  
Hongchao Wang ◽  
Scott Draper ◽  
Wenhua Zhao ◽  
Hugh Wolgamot ◽  
Liang Cheng
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Domain Size ◽  
Cfd Model ◽  
Transient Wave ◽  
Wave Groups ◽  
Mesh Topology ◽  
Gap Resonance ◽  
Viscous Losses ◽  
Computational Fluid Dynamics Cfd

This paper addresses the process of establishing a numerical model to accurately reproduce experimental results presented by Zhao et al. (2017) of three-dimensional (3D) gap resonance between two fixed ship-shaped boxes. The ship-shaped boxes were arranged in a side-by-side configuration to represent FLNG offloading and were subjected to NewWave-type transient wave groups. To develop the numerical model we employ the open-source Computational Fluid Dynamics (CFD) package OpenFOAM and systematically optimize mesh topology and size, domain size and boundary conditions. CFD is necessary for this problem to accurately reproduce the viscous losses and non-linear free surface effects that are observed in the experiments. The incident transient wave group used in the experiment is regenerated using various iterative schemes. The results show satisfactory agreements between the target and regenerated waves.

Mechanism and Flow Control on the Mismatching of Impeller and Vaned Diffuser Caused by Inlet Prewhirl for Centrifugal Compressors

2016 ◽  
Author(s):  
Qiangqiang Huang ◽  
Xinqian Zheng ◽  
Aolin Wang
Keyword(s):  
Flow Control ◽  
Control Method ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Vaned Diffuser ◽  
Inlet Distortion ◽  
Computational Fluid Dynamics Cfd ◽  
Stagger Angle ◽  
Good Agreement ◽  
Matching Relation

Air often flows into compressors with inlet prewhirl, because it will obtain a circumferential component of velocity via inlet distortion or swirl generators such as inlet guide vanes. A lot of research has shown that inlet prewhirl does influence the characteristics of components, but the change of the matching relation between the components caused by inlet prewhirl is still unclear. This paper investigates the influence of inlet prewhirl on the matching of the impeller and the diffuser and proposes a flow control method to cure mismatching. The approach combines steady three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations with theoretical analysis and modeling. The result shows that a compressor whose impeller and diffuser match well at zero prewhirl will go to mismatching at non-zero prewhirl. The diffuser throat gets too large to match the impeller at positive prewhirl and gets too small for matching at negative prewhirl. The choking mass flow of the impeller is more sensitive to inlet prewhirl than that of the diffuser, which is the main reason for the mismatching. To cure the mismatching via adjusting the diffuser vanes stagger angle, a one-dimensional method based on incidence matching has been proposed to yield a control schedule for adjusting the diffuser. The optimal stagger angle predicted by analytical method has good agreement with that predicted by computational fluid dynamics (CFD). The compressor is able to operate efficiently in a much broader flow range with the control schedule. The flow range, where the efficiency is above 80%, of the datum compressor and the compressor only employing inlet prewhirl and no control are just 25.3% and 31.8%, respectively. For the compressor following the control schedule, the flow range is improved up to 46.5%. This paper also provides the perspective of components matching to think about inlet distortion.

scholarly journals Three-Dimensional Navier–Stokes Analysis and Redesign of an Imbedded Bellmouth Nozzle in a Turbine Cascade Inlet Section

1996 ◽  
Vol 118 (3) ◽  
pp. 529-535 ◽  
Author(s):  
P. W. Giel ◽  
J. R. Sirbaugh ◽  
I. Lopez ◽  
G. J. Van Fossen
Keyword(s):  
Three Dimensional ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Inlet Section ◽  
Turbine Cascade ◽  
Blade Cascade ◽  
Inlet Geometry ◽  
Computational Fluid Dynamics Cfd ◽  
Transonic Turbine ◽  
Flow Nonuniformity

Experimental measurements in the inlet of a transonic turbine blade cascade showed unacceptable pitchwise flow nonuniformity. A three-dimensional, Navier–Stokes computational fluid dynamics (CFD) analysis of the imbedded bellmouth inlet in the facility was performed to identify and eliminate the source of the flow nonuniformity. The blockage and acceleration effects of the blades were accounted for by specifying a periodic static pressure exit condition interpolated from a separate three-dimensional Navier–Stokes CFD solution of flow around a single blade in an infinite cascade. Calculations of the original inlet geometry showed total pressure loss regions consistent in strength and location to experimental measurements. The results indicate that the distortions were caused by a pair of streamwise vortices that originated as a result of the interaction of the flow with the imbedded bellmouth. Computations were performed for an inlet geometry that eliminated the imbedded bellmouth by bridging the region between it and the upstream wall. This analysis indicated that eliminating the imbedded bellmouth nozzle also eliminates the pair of vortices, resulting in a flow with much greater pitchwise uniformity. Measurements taken with an installed redesigned inlet verify that the flow nonuniformity has indeed been eliminated.

Turbine Airfoil Heat Transfer Predictions Using CFD

2005 ◽  
Author(s):  
Anil K. Tolpadi ◽  
James A. Tallman ◽  
Lamyaa El-Gabry
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulence Modeling ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Design System ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Airfoils ◽  
Typical Design

Conventional heat transfer design methods for turbine airfoils use 2-D boundary layer codes (BLC) combined with empiricism. While such methods may be applicable in the mid span of an airfoil, they would not be very accurate near the end-walls and airfoil tip where the flow is very three-dimensional (3-D) and complex. In order to obtain accurate heat transfer predictions along the entire span of a turbine airfoil, 3-D computational fluid dynamics (CFD) must be used. This paper describes the development of a CFD based design system to make heat transfer predictions. A 3-D, compressible, Reynolds-averaged Navier-Stokes CFD solver with k-ω turbulence modeling was used. A wall integration approach was used for boundary layer prediction. First, the numerical approach was validated against a series of fundamental airfoil cases with available data. The comparisons were very favorable. Subsequently, it was applied to a real engine airfoil at typical design conditions. A discussion of the features of the airfoil heat transfer distribution is included.

scholarly journals A computational investigation of the hydrodynamics of the Badush dam in northern Iraq

2018 ◽  
Vol 240 ◽  
pp. 04009
Author(s):  
Younis Saida Saeedrashed ◽  
Ali Cemal Benim
Keyword(s):  
Three Dimensional ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Dam Failure ◽  
Northern Iraq ◽  
Digital Elevation ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Elevation Model ◽  
Bottom Outlets

A computational analysis of the hydrodynamics of the Badush dam in Iraq is presented, which is planned to be reconstructed as a repulse dam, to prevent the Mosul city, in case of a failure of the Mosul dam. Computational Fluid Dynamics (CFD) is applied in combination with Geometric Information System (GIS) and Digital Elevation Model (DEM). In the first part of the study, a hydrologic study of a possible Mosul dam failure is performed, predicting the important parameters for a possible flooding of Mosul city. Here, a two-dimensional, depth-averaged shallow water equations are used to formulate the flow. Based on GIS and DEM, the required reservoir size and the water level of the Badush dam are predicted, for its acting as a repulse dam. Subsequently, a computational model of the reconstructed Badush dam is developed, combining the proposed construction with the local geographic topology to achieve a perfect fit. Finally, the water flow through the bottom outlets and stilling basin of the proposed dam is calculated by an unsteady, three-dimensional CFD analysis of the turbulent, free-surface flow. The CFD model is validated by comparing the predictions with measurements obtained on a physical model, where a quite satisfactory agreement is observed.

Mechanisms of Non-Newtonian Polymer Flow Through Porous Media Using Navier–Stokes Approach

2014 ◽  
Vol 36 (3) ◽  
pp. 310-325 ◽  
Author(s):  
Nematollah Zamani ◽  
Roland Kaufmann ◽  
Pawel Kosinski ◽  
Arne Skauge
Keyword(s):  
Porous Media ◽  
Navier Stokes ◽  
Flow Through Porous Media ◽  
Polymer Flow ◽  
Flow Through
Sign in / Sign up

Export Citation Format

Share Document