Implementation of Infinite Height Levee in CaFunwave Using an Immersed Boundary Method

2015 ◽  
Author(s):  
Adam M. Oler ◽  
Ning Zhang ◽  
Steven R. Brandt
Keyword(s):  
Immersed Boundary Method ◽  
Large Scale ◽  
Shallow Water Equation ◽  
Immersed Boundary ◽  
Immersed Boundary Methods ◽  
Boundary Method ◽  
Shape Effects ◽  
Infinite Height ◽  
Grid Points ◽  
Complicated Geometries

Numerical simulations of storm-surge-wave actions on coastal highways and levees are very important research topics for coastal Louisiana. In a large scale region hydrodynamic model, highways and levees are often complicated in geometry and much smaller in size compared to the grid size. The immersed boundary method (IBM) allows for those complicated geometries to be modeled in a less expensive way. It can allow very small geometries to be modeled in a large scale simulation, without requiring them to be explicitly on the grid. It can also allow for complicated geometries not collocated on the grid points. CaFunwave is a project that uses the Cactus Framework for modeling a solitary coastal wave impinging on a coastline, and is the wave solver in this research. The IBM allows for a levee with different geometries to be implemented on a simple Cartesian grid in the CaFunwave package. The IBM has not been used previously for this type of application. Implementing an infinite height levee using the IBM in the Cactus CaFunwave code involves introducing IB forcing terms into the standard 2-D depth averaged shallow water equation set. These forcing terms cause the 2-D solitary wave to experience a virtual force at the grid points surrounding the immersed boundary levee. In this paper the levee was implemented and tested using two different immersed boundary methods. The first method was a feedback-force method, which proved to be more effective at modeling the levee than the second method, the direct-forcing method. In this study, the results of the two methods, as well as the shape effects on the flow, are presented and discussed.

Implementation of an Infinite-Height Levee in CaFunwave Using an Immersed-Boundary Method

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Adam Oler ◽  
Ning Zhang ◽  
Steven R. Brandt ◽  
Qin Chen
Keyword(s):  
Immersed Boundary Method ◽  
Large Scale ◽  
Shallow Water Equation ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Virtual Force ◽  
Direct Forcing ◽  
Infinite Height ◽  
Grid Points ◽  
Complicated Geometries

Numerical simulations of storm-surge–wave actions on coastal highways and levees are very important research topics for coastal engineering. In a large-scale region hydrodynamic model, highways and levees are often complicated in geometry and much smaller in size compared to the grid spacing. The immersed-boundary method (IBM) allows for those complicated geometries to be modeled in a less expensive way. It can allow very small geometries to be modeled in a large-scale simulation, without requiring them to be explicitly on the grid. It can also allow for complicated geometries not collocated on the grid points. CaFunwave is a project that uses the Cactus Framework for modeling a solitary coastal wave impinging on a coastline and is the wave solver in this research. The IBM allows for a levee with different geometries to be implemented on a simple Cartesian grid in the CaFunwave package. The IBM has not been often used previously for these types of applications. Implementing an infinite-height levee using the IBM into the Cactus project CaFunwave involves introducing immersed-boundary (IB) forcing terms into the standard two-dimensional (2D) depth-averaged shallow water equation set. These forcing terms cause the 2D solitary wave to experience a virtual force at the grid points surrounding the IB levee. In this paper, the levee was implemented and tested using two different IBMs. The first method was a feedback-forcing method, which proved to be more effective at modeling the levee than the second method, the direct-forcing method. In this study, the results of the two methods are presented and discussed. The effect of levee shape on the flow is also investigated and discussed in this paper.

Multi-Scale Modeling of Wind-Wave Interaction in the Presence of Offshore Structures for Renewable Energy Applications

2010 ◽  
Author(s):  
Yi Liu ◽  
Di Yang ◽  
Xin Guo ◽  
Lian Shen
Keyword(s):  
Immersed Boundary Method ◽  
Large Scale ◽  
Wind Wave ◽  
Offshore Structures ◽  
Local Scale ◽  
Immersed Boundary ◽  
Multi Scale ◽  
Scale Modeling ◽  
Boundary Method ◽  
Multi Scale Modeling

We develop a multi-scale modeling capability for the simulation of wind and wave coupling dynamics, with a focus on providing environmental input for wind and wave loads on offshore structures. For the large-scale wind–wave environment, large-eddy simulation for the wind turbulence and high-order spectral simulation for the nonlinear ocean waves are dynamically coupled. For the local-scale air and water flows past the structure, we use a hybrid interface capturing and immersed boundary method. Coupled level-set/volume-of-fluid/ghost-fluid method is used to capture the wave surface. Immersed boundary method is used to represent the structure. The large-scale wind–wave simulation provides inflow boundary conditions for the local-scale air–water–structure simulation. Our simulation captures the dynamic evolution of ocean nonlinear wavefield under the wind action. The wind field is found to be strongly coupled with the surface waves and the wind load on a surface-piercing object is largely wave-phase dependent.

An New Immersed Boundary Method With Level Set Based Geometry Representation and Volume Fraction Based Body Force Calculation

2018 ◽  
Author(s):  
Guangfa Yao
Keyword(s):  
Level Set ◽  
Immersed Boundary Method ◽  
Body Force ◽  
Volume Fraction ◽  
The Body ◽  
Immersed Boundary ◽  
Immersed Boundary Methods ◽  
Boundary Method ◽  
Boundary Methods ◽  
Fluid Solid Interaction

Immersed boundary method has got increasing attention in modeling fluid-solid interaction using computational fluid dynamics due to its robustness and simplicity. It simulates fluid-solid interaction by adding a body force in the momentum equation without a body conforming mesh generation involved. Different immersed boundary methods have been presented and applied to solve fluid flow with immersed solid bodies. The main difference between these immersed boundary methods is how the body force is calculated. In this paper, a new immersed boundary method is proposed. The body force is calculated based on the volume fraction of the solid body immersed in fluid. Compared to the existing and similar methods, the new method develops a mechanism to calculate the body force and thereby more accurately resolve the physics on the solid-fluid interface. The solid body is represented using a level set that facilitates the calculation of the solid volume fraction. The body force derivation is presented and the method is validated against the test cases with existing analytical solutions or well established numerical solutions. A good match was reached.

An Immersed Boundary Method Based on the Kinematic Relation of the Velocity-Vorticity Formulation

2014 ◽  
Vol 31 (2) ◽  
pp. 171-181 ◽  
Author(s):  
I. Farahbakhsh ◽  
H. Ghassemi ◽  
F. Sabetghadam
Keyword(s):  
Immersed Boundary Method ◽  
Rigid Motion ◽  
Rigid Bodies ◽  
Immersed Boundary ◽  
Test Cases ◽  
Immersed Boundary Methods ◽  
Vorticity Field ◽  
Boundary Method ◽  
New Interpretation ◽  
Boundary Methods

AbstractAn immersed boundary method is proposed for the simulation of the interaction of an incompressible flow with rigid bodies. The method is based on a new interpretation of velocity-vorticity formulation and no longer includes the force term which is an essential issue of common immersed boundary methods. The system is considered in an Eulerian frame and retrieving the vorticity in this formulation enforces continuity at the fluid-solid interface and rigid motion of the solid. The method focuses on the mutual kinematic relations between the velocity and vorticity fields and with retrieving the vorticity field and recalculating the velocities yields the solenoidal velocity field. The method is applied to the two dimensional problems and the results show that the solenoidality is satisfied acceptably. The comparisons with 2D test cases are provided to illustrate the capabilities of the proposed method.

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