Complementary approximations to wave scattering by vertical barriers

1995 ◽  
Vol 294 ◽  
pp. 155-180 ◽  
Author(s):  
R. Porter ◽  
D. V. Evans

Scattering of waves by vertical barriers in infinite-depth water has received much attention due to the ability to solve many of these problems exactly. However, the same problems in finite depth require the use of approximation methods. In this paper we present an accurate method of solving these problems based on a Galerkin approximation. We will show how highly accurate complementary bounds can be computed with relative ease for many scattering problems involving vertical barriers in finite depth and also for a sloshing problem involving a vertical barrier in a rectangular tank.

1999 ◽  
Vol 122 (2) ◽  
pp. 100-108 ◽  
Author(s):  
B. N. Mandal ◽  
Mridula Kanoria

This paper is concerned with scattering of an obliquely incident surface water wave train by an obstacle in the form of a thick horizontal barrier of rectangular cross section present in finite depth water. Four different geometrical configurations of the obstacle are considered. It may be surface-piercing or bottom-standing, or in the form of a submerged block not extending down to the bottom, or in the form of a thick wall with a submerged gap. Multi-term Galerkin approximations involving ultraspherical Gegenbauer polynomials for solving first-kind integral equations are utilized in the mathematical analysis to obtain very accurate numerical estimates for the reflection coefficient, which are depicted graphically against the wave number for each configurations of the thick barrier. [S0892-7219(00)00701-9]


2019 ◽  
Vol 24 (4) ◽  
pp. 157-168
Author(s):  
S. Ray ◽  
S. De ◽  
B.N. Mandal

Abstract The classical problem of water wave scattering by an infinite step in deep water with a free surface is extended here with an ice-cover modelled as a thin uniform elastic plate. The step exists between regions of finite and infinite depths and waves are incident either from the infinite or from the finite depth water region. Each problem is reduced to an integral equation involving the horizontal component of velocity across the cut above the step. The integral equation is solved numerically using the Galerkin approximation in terms of simple polynomial multiplied by an appropriate weight function whose form is dictated by the behaviour of the fluid velocity near the edge of the step. The reflection and transmission coefficients are obtained approximately and their numerical estimates are seen to satisfy the energy identity. These are also depicted graphically against thenon-dimensional frequency parameter for various ice-cover parameters in a number of figures. In the absence of ice-cover, the results for the free surface are recovered.


1996 ◽  
Vol 18 (6) ◽  
pp. 319-327 ◽  
Author(s):  
Sudeshna Banerjea ◽  
Mridula Kanoria ◽  
D.P. Dolai ◽  
B.N. Mandal

2000 ◽  
Vol 42 (1-2) ◽  
pp. 319-324 ◽  
Author(s):  
H. Rubin ◽  
A. Rabideau

This study presents an approximate analytical model, which can be useful for the prediction and requirement of vertical barrier efficiencies. A previous study by the authors has indicated that a single dimensionless parameter determines the performance of a vertical barrier. This parameter is termed the barrier Peclet number. The evaluation of barrier performance concerns operation under steady state conditions, as well as estimates of unsteady state conditions and calculation of the time period requires arriving at steady state conditions. This study refers to high values of the barrier Peclet number. The modeling approach refers to the development of several types of boundary layers. Comparisons were made between simulation results of the present study and some analytical and numerical results. These comparisons indicate that the models developed in this study could be useful in the design and prediction of the performance of vertical barriers operating under conditions of high values of the barrier Peclet number.


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