A three-dimensional infinite element for modeling open-boundary field problems

1992 ◽  
Vol 28 (2) ◽  
pp. 1675-1678 ◽  
Author(s):  
S. Gratkowski ◽  
M. Ziolkowski
Keyword(s):  
Three Dimensional ◽  
Open Boundary ◽  
Infinite Element ◽  
Boundary Field

scholarly journals Impact of Channel Geometry and Rotation on the Trapping of Internal Tides

2007 ◽  
Vol 37 (11) ◽  
pp. 2740-2763 ◽  
Author(s):  
Sybren Drijfhout ◽  
Leo R. M. Maas
Keyword(s):  
Continental Slope ◽  
Three Dimensional ◽  
Tidal Energy ◽  
Ocean Model ◽  
Internal Tides ◽  
Open Boundary ◽  
Kelvin Wave ◽  
Channel Geometry ◽  
Channel Slope ◽  
The Cross

Abstract The generation and propagation of internal tides has been studied with an isopycnic three-dimensional ocean model. The response of a uniformly stratified sea in a channel, which is forced by a barotropic tide on its open boundary, is considered. The tide progresses into the channel and forces internal tides over a continental slope at the other end. The channel has a length of 1200 km and a width of 191.25 km. The bottom profile has been varied. In a series of four experiments it is shown how the cross-channel geometry affects the propagation and trapping of internal tides, and the penetration scale of wave energy, away from the continental slope, is discussed. In particular it is found that a cross-channel bottom slope constrains the penetration of the internal tidal energy. Most internal waves refract toward a cross-channel plane where they are trapped. The exception is formed by edge waves that carry part of the energy away from the continental slope. In the case of rotation near the continental slope, the Poincaré waves that arise in the absence of a cross-channel slope no longer bear the characteristics of the wave attractor predicted by 2D theory, but are almost completely arrested, while the right-bound Kelvin wave preserves the 2D attractor in the cross-channel plane, which is present in the nonrotating case. The reflected, barotropic right-bound Kelvin wave acts as a secondary internal wave generator along the cross-channel slope.

Efficient Structural Acoustic Analysis Using Finite and Infinite Elements and Parallel Processing Architectures

1997 ◽  
Author(s):  
Stewart W. Moore ◽  
Henno Allik
Keyword(s):  
Acoustic Analysis ◽  
Three Dimensional ◽  
Infinite Element ◽  
Analytical Technique ◽  
Infinite Elements ◽  
Infinite Element Method ◽  
Modeling Practices ◽  
Processing Architectures ◽  
Memory Architectures ◽  
Element Theory

Abstract The analysis of three-dimensional shell structures submerged in an infinite fluid and subjected to arbitrary loadings is a computationally demanding problem regardless of the analytical technique used. Over the past several years, we have developed a combined finite/infinite element method of solving this class of problems that is more efficient than other available techniques, and have implemented it in a comprehensive set of computer programs called SARA. This paper presents an overview of our work in parallizing this software. In the first part of the paper, we describe our method for solving the fluid-structure interaction equations including infinite element theory, and modeling practices that have evolved for solving cylindrical geometries. The second part of the paper addresses parallalization of SARA-3D on both shared and distributed memory architectures. The SARA implementation of the method is described along with sample problems, and a comparison to a SARA-3D solution is provided.

Entrainment and growth of vortical disturbances in the channel-entrance region

2021 ◽  
Vol 927 ◽  
Author(s):  
Pierre Ricco ◽  
Claudia Alvarenga
Keyword(s):  
Initial Conditions ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Analytical Description ◽  
Reynolds Numbers ◽  
Boundary Region ◽  
Shear Layers ◽  
Base Flow ◽  
Open Boundary ◽  
Classical Stability

The entrainment of free-stream unsteady three-dimensional vortical disturbances in the entry region of a channel is studied via matched asymptotic expansions and by numerical means. The interest is in flows at Reynolds numbers where experimental studies have documented the occurrence of intense transient growth, despite the flow being stable according to classical stability analysis. The analytical description of the vortical perturbations at the channel mouth reveals how the oncoming disturbances penetrate into the wall-attached shear layers and amplify downstream. The effects of the channel confinement, the streamwise pressure gradient and the viscous/inviscid interplay between the oncoming disturbances and the boundary-layer perturbations are discussed. The composite perturbation velocity profiles are employed as initial conditions for the unsteady boundary-region perturbation equations. At a short distance from the channel mouth, the disturbance flow is mostly confined within the shear layers and assumes the form of streamwise-elongated streaks, while farther downstream the viscous disturbances permeate the whole channel although the base flow is still mostly inviscid in the core. Symmetrical disturbances exhibit a more significant growth than anti-symmetrical disturbances, the latter maintaining a nearly constant amplitude for several channel heights downstream before growing transiently, a unique feature not reported in open boundary layers. The disturbances are more intense as the frequency decreases or the bulk Reynolds number increases. We compute the spanwise wavelengths that cause the most intense downstream growth and the threshold wall-normal wavelengths below which the perturbations are damped through viscous dissipation.

Towards a General-Purpose Open Boundary Condition for Wave Simulations

2011 ◽  
Author(s):  
Bulent Duz ◽  
Rene H. M. Huijsmans ◽  
Peter R. Wellens ◽  
Mart J. A. Borsboom ◽  
Arthur E. P. Veldman
Keyword(s):  
Boundary Condition ◽  
Three Dimensional ◽  
General Purpose ◽  
Absorbing Boundary Conditions ◽  
Design Stage ◽  
Open Boundary ◽  
Computational Domain ◽  
Absorbing Boundary ◽  
Scaled Model ◽  
Artificial Boundaries

For the design of FPSO’s in harsh environments an accurate assessment of the ability of the platform to survive in extreme sea conditions is of prime importance. Next to scaled model tests on the FPSO in waves also CFD capabilities are at the disposal of the designer. However even with the fastest computers available it is still a challenge to use CFD in the design stage because of the large computational resources they require. In that respect to use a small computational domain will improve the turn around time of the computations, however at the expense of various numerical artifacts, like reflection on artificial boundaries in the computational domain. In order to mitigate the reflection properties new absorbing boundary conditions have been developed. The work in this paper is constructed on the previous study about the generating and absorbing boundary condition (GABC) in the ComFLOW project. We present a method to apply the GABC on all the boundaries in a three dimensional domain. The implementation of the GABC in ComFLOW is explained in detail.

The application of the database method for 3-D open boundary field computation

1992 ◽  
Vol 28 (2) ◽  
pp. 1686-1689 ◽  
Author(s):  
W. Chen ◽  
G.S. Zhang ◽  
Y.S. Sun ◽  
M.J. Chen ◽  
Y. Zhao
Keyword(s):  
Open Boundary ◽  
Boundary Field ◽  
Field Computation
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