Numerical Simulation of Wave Propagation Over Submerged Composite Breakwaters Using the Immersed Boundary Method

2014 ◽  
Author(s):  
Theofano I. Koutrouveli ◽  
Athanassios A. Dimas
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Immersed Boundary Method ◽  
Stokes Equations ◽  
Splitting Method ◽  
Staggered Grid ◽  
Immersed Boundary ◽  
Two Phase ◽  
Boundary Method ◽  
Two Dimensional Flow

The two-dimensional flow induced by waves over submerged breakwaters of two different shapes is studied by means of a two-phase (water and air) Navier-Stokes equations solver. A time-splitting method is used for the temporal discretization, while the spatial discretization is based on the use of finite differences in a Cartesian staggered grid. The implementation of the boundary conditions at solid surfaces, as well as the treatment of the free surface is performed using the immersed boundary method where the breakwater, the seabed and the free surface are boundaries immersed in the numerical grid. The numerical model was applied on the propagation and breaking over a constant slope beach, as well as on the propagation and nonlinear transformation of waves over two types of submerged breakwaters, i.e., trapezoidal and composite (with berm in the up-slope side). The results of the numerical model reveal that the presence of the berm reduces the transmission coefficient and this reduction increases with the decrease of the berm depth of submergence.

An Immersed Boundary Method for Compressible Flows with Complex Boundaries

2013 ◽  
Vol 477-478 ◽  
pp. 281-284
Author(s):  
Jie Yang ◽  
Song Ping Wu
Keyword(s):  
Immersed Boundary Method ◽  
Compressible Flows ◽  
Stokes Equations ◽  
Splitting Method ◽  
Linear Interpolation ◽  
High Order Accuracy ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Central Difference ◽  
Boundary Method

An immersed boundary method based on the ghost-cell approach is presented in this paper. The compressible Navier-Stokes equations are discretized using a flux-splitting method for inviscid fluxes and second-order central-difference for the viscous components. High-order accuracy is achieved by using weighted essentially non-oscillatory (WENO) and Runge-Kutta schemes. Boundary conditions are reconstructed by a serial of linear interpolation and inverse distance weighting interpolation of flow variables in fluid domain. Two classic flow problems (flow over a circular cylinder, and a NACA 0012 airfoil) are simulated using the present immersed boundary method, and the predictions show good agreement with previous computational results.

scholarly journals A Discrete-Forcing Immersed Boundary Method for Moving Bodies in Air–Water Two-Phase Flows

2020 ◽  
Vol 8 (10) ◽  
pp. 809
Author(s):  
Haixuan Ye ◽  
Yang Chen ◽  
Kevin Maki
Keyword(s):  
Free Surface ◽  
Immersed Boundary Method ◽  
Surface Profile ◽  
Field Extension ◽  
Immersed Boundary ◽  
Two Phase Flows ◽  
Two Phase ◽  
Practical Applications ◽  
Boundary Method ◽  
Immersed Boundaries

For numerical simulations of ship and offshore hydrodynamic problems, it is challenging to model the interaction between the free surface and moving complex geometries. This paper proposes a discrete-forcing immersed boundary method (IBM) to efficiently simulate moving solid boundaries in incompressible air–water two-phase flows. In the present work, the air–water two-phase flows are modeled using the Volume-of-Fluid (VoF) method. The present IBM is suitable for unstructured meshes. It can be used combined with body-fitted wall boundaries to model the relative motions between solid walls, which makes it flexible to use in practical applications. A field extension method is used to model the interaction between the air–water interface and the immersed boundaries. The accuracy of the method is demonstrated through validation cases, including the three-dimensional dam-break problem with an obstacle, the water exit of a circular cylinder, and a ship model advancing with a rotating semi-balanced rudder. The flow field, free-surface profile and force on the immersed boundaries (IBs) are in good agreement with experimental data and other numerical results.

A combined volume of fluid and immersed boundary method for free surface simulations induced by solitary waves

2022 ◽  
Vol 245 ◽  
pp. 110560
Author(s):  
Qiu Jin ◽  
Dominic Hudson ◽  
Pandeli Temarel
Keyword(s):  
Free Surface ◽  
Solitary Waves ◽  
Immersed Boundary Method ◽  
Volume Of Fluid ◽  
Immersed Boundary ◽  
Boundary Method

FINITE ELEMENT APPROACH TO IMMERSED BOUNDARY METHOD WITH DIFFERENT FLUID AND SOLID DENSITIES

2011 ◽  
Vol 21 (12) ◽  
pp. 2523-2550 ◽  
Author(s):  
DANIELE BOFFI ◽  
NICOLA CAVALLINI ◽  
LUCIA GASTALDI
Keyword(s):  
Finite Element ◽  
Immersed Boundary Method ◽  
Stokes Equations ◽  
Numerical Procedure ◽  
Biological Tissues ◽  
Immersed Boundary ◽  
Fluid Structure ◽  
Finite Element Approach ◽  
Boundary Method ◽  
Element Approach

The Immersed Boundary Method (IBM) has been designed by Peskin for the modeling and the numerical approximation of fluid-structure interaction problems, where flexible structures are immersed in a fluid. In this approach, the Navier–Stokes equations are considered everywhere and the presence of the structure is taken into account by means of a source term which depends on the unknown position of the structure. These equations are coupled with the condition that the structure moves at the same velocity of the underlying fluid. Recently, a finite element version of the IBM has been developed, which offers interesting features for both the analysis of the problem under consideration and the robustness and flexibility of the numerical scheme. Initially, we considered structure and fluid with the same density, as it often happens when dealing with biological tissues. Here we study the case of a structure which can have a density higher than that of the fluid. The higher density of the structure is taken into account as an excess of Lagrangian mass located along the structure, and can be dealt with in a variational way in the finite element approach. The numerical procedure to compute the solution is based on a semi-implicit scheme. In fluid-structure simulations, nonimplicit schemes often produce instabilities when the density of the structure is close to that of the fluid. This is not the case for the IBM approach. In fact, we show that the scheme enjoys the same stability properties as in the case of equal densities.

A new immersed boundary method for compressible Navier–Stokes equations

2013 ◽  
Vol 27 (3) ◽  
pp. 151-163 ◽  
Author(s):  
Jianming Liu ◽  
Ning Zhao ◽  
Ou Hu ◽  
Mikhail Goman ◽  
Xin Kai Li
Keyword(s):  
Immersed Boundary Method ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Navier Stokes Equations ◽  
Boundary Method

scholarly journals A Ghost-Cell Immersed Boundary Method for Wave–Structure Interaction Using a Two-Phase Flow Model

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3346
Author(s):  
Yuan-Shiang Tsai ◽  
Der-Chang Lo
Keyword(s):  
Immersed Boundary Method ◽  
Flow Model ◽  
Two Phase Flow ◽  
Immersed Boundary ◽  
Phase Flow ◽  
Ghost Cell ◽  
Two Phase ◽  
Boundary Method ◽  
Lift Forces ◽  
Drag And Lift

The air-water two-phase flow model is developed to study the transformation of monochromatic waves passing over the submerged structure. The level set method is employed to describe the motion of the interface while the effect of the immersed object on the fluid is resolved using the ghost-cell immersed boundary method. The computational domain integrated with the air-water and fluid-solid phases allows the use of uniform Cartesian grids. The model simulates the wave generation, wave decomposition over a submerged trapezoidal breakwater, and the formation of the vortices as well as the drag and lift forces caused by the surface waves over three different configurations of the submerged structures. The numerical results show the capability of the present model to accurately track the deformation of the free surface. In addition, the variation of the drag and lift forces depend on the wavelength and wave induced vortices around the submerged object. Hence, the study observes that the triangular structure experiences the relatively small wave force.

scholarly journals A Stress Mapping Immersed Boundary Method for Viscous Flows

2021 ◽  
Vol 87 (3) ◽  
pp. 1-20
Author(s):  
Karim M. Ali ◽  
Mohamed Madbouli ◽  
Hany M. Hamouda ◽  
Amr Guaily
Keyword(s):  
Immersed Boundary Method ◽  
Stokes Equations ◽  
Cross Flow ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Element Formulation ◽  
Navier Stokes Equations ◽  
Boundary Method ◽  
Background Grid ◽  
Dimensional Simulation

This work introduces an immersed boundary method for two-dimensional simulation of incompressible Navier-Stokes equations. The method uses flow field mapping on the immersed boundary and performs a contour integration to calculate immersed boundary forces. This takes into account the relative location of the immersed boundary inside the background grid elements by using inverse distance weights, and also considers the curvature of the immersed boundary edges. The governing equations of the fluid mechanics are solved using a Galerkin-Least squares finite element formulation. The model is validated against a stationary and a vertically oscillating circular cylinder in a cross flow. The results of the model show acceptable accuracy when compared to experimental and numerical results.

A Combined Volume of Fluid and Immersed Boundary Method for Modelling of Two-Phase Flows with High Density Ratio

2021 ◽  
Author(s):  
Qiu Jin ◽  
Dominic Hudson ◽  
W.G. Price
Keyword(s):  
Boundary Layer ◽  
Immersed Boundary Method ◽  
Density Ratio ◽  
Volume Of Fluid ◽  
High Density ◽  
Immersed Boundary ◽  
Two Phase Flows ◽  
Two Phase ◽  
Boundary Method ◽  
High Density Ratio

Abstract A combined volume of fluid and immersed boundary method is developed to simulate two-phase flows with high density ratio. The problems of discontinuity of density and momentum flux are known to be challenging in simulations. In order to overcome the numerical instabilities, an extra velocity field is designed to extend velocity of the heavier phase into the lighter phase and to enforce a new boundary condition near the interface, which is similar to non-slip boundary conditions in Fluid-Structure Interaction (FSI) problems. The interface is captured using a Volume of Fluid (VOF) method, and a new boundary layer is built on the lighter phase side by an immersed boundary method. The designed boundary layer helps to reduce the spurious velocity caused by the imbalance of dynamic pressure gradient and density gradient and to prevent tearing of the interface due to the tangential velocity across the interface. The influence of time step, density ratio, and spatial resolution is studied in detail for two set of cases, steady stratified flow and convection of a high-density droplet, where direct comparison is possible to potential flow analysis (i.e. infinite Reynold's number). An initial study for a droplet splashing on a thin liquid film demonstrates applicability of the new solver to real-life applications. Detailed comparisons should be performed in the future for finite Reynold's number cases to fully demonstrate the improvements in accuracy and stability of high-density ratio two-phase flow simulations offered by the new method.

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