Trilochan Sahoo

Bio: Trilochan Sahoo is an academic researcher from Indian Institute of Technology Kharagpur. The author has contributed to research in topics: Reflection (physics) & Surface wave. The author has an hindex of 25, co-authored 142 publications receiving 1950 citations. Previous affiliations of Trilochan Sahoo include Indian Institute of Science & University of Hong Kong.

Scattering of surface waves by a semi-infinite floating elastic plate

Abstract: A new inner product is developed based on the Fourier analysis to study the scattering of surface waves by a floating semi-infinite elastic plate in a two-dimensional water domain of finite depth. The eigenfunctions for the plate-covered region are orthogonal with respect to this new inner product. The problem is studied for various wave and geometrical conditions. Especially, the influence of different edge conditions on the hydrodynamic behavior is investigated and compared. The edge conditions considered in the present study involve (i) a free edge, (ii) a simply supported edge, and (iii) a built-in edge. The hydrodynamic performance of an elastic plate is characterized for various conditions in terms of wave reflection and transmission, plate deflection, and surface strain. It is observed that the hydrodynamic behavior depends on the wave conditions, the geometrical settings, and the edge conditions. The built-in edge condition induces the maximum wave reflection and the minimum wave transmission. The free edge condition leads to the maximum plate deflection.

Trapping and Generation of Waves by Vertical Porous Structures

Abstract: The trapping and generation of surface waves by submerged vertical permeable barriers or plates kept at one end of a semi-infinitely long channel of finite depth are investigated for various barrier and plate configurations. The various fixed barrier configurations are (1) a surface-piercing barrier; (2) a bottom-touching barrier; (3) a barrier with a gap; and (4) a fully submerged barrier. The different moving plate (or wavemaker) configurations are of types 1, 2, and 4, respectively. The boundary value problems are converted to dual/triple series relations by a suitable application of the eigenfunction expansion method and then the full solutions are obtained by the least-squares method. The variations of reflection coefficients are obtained and discussed for different values of the porous-effect parameter, the normalized distance between the barrier and the channel end-wall, and the length of submergence of barriers for all types of barrier configurations. The dynamic pressure distributions for various...

Expansion formulae in wave structure interaction problems

Abstract: A large class of problems in the field of fluid–structure interaction involves higher-order boundary conditions for the governing partial differential equation and the eigenfunctions associated with these problems are not orthogonal in the usual sense. In the present study, mode-coupling relations are derived by utilizing the Fourier integral theorem for the solutions of the Laplace equation with higher-order derivatives in the boundary conditions in both the cases of a semi-infinite strip and a semi-infinite domain in two dimensions. The expansion for the velocity potential is derived in terms of the corresponding eigenfunctions of the boundary-value problem. Utilizing such an expansion of the velocity potential, the symmetric wave source potentials or the socalled Green’s function for the boundary-value problem of the flexural gravity wave maker is derived. Alternatively, utilizing the integral form of the wave source potential, the expansion formulae for the velocity potentials are recovered, which justifies the completeness of the eigenfunctions involved. As an application of the wave maker problem, oblique water wave scattering caused by cracks in a floating ice-sheet is analysed in the case of infinite depth.

Oblique Wave Trapping by Porous Structures Near a Wall

Abstract: The current study deals with the oblique wave trapping by bottom-standing and surface-piercing porous structures of finite width placed at a finite distance from a vertical rigid wall Using the Sollitt and Cross model for wave motion within the porous structure, the problems are analyzed based on the small-amplitude water wave theory in water of finite depth The solutions of the associated boundary value problems are obtained analytically using the eigenfunction expansion method and numerically using a multidomain boundary-element method In the boundary-element method, the boundary value problems are converted into integral equations over the physical boundaries The physical boundaries are discretized into a finite number of elements to obtain a system of linear algebraic equations Various aspects of structural configurations, in trapping surface gravity waves, are analyzed from the computed results on the reflection coefficients and the hydrodynamic forces Suitable arrangements of the rigid

Hydroelastic analysis of gravity wave interaction with submerged horizontal flexible porous plate

Abstract: The present study deals with the surface gravity wave interaction with submerged horizontal flexible porous plate under the assumption of small amplitude water wave theory and structural response. The flexible porous plate is modeled using the thin plate theory and wave past porous structure is based on the generalized porous wavemaker theory. The wave characteristics due to the interaction of gravity waves with submerged flexible porous structure are studied by analyzing the complex dispersion relation using contour plots. Three different problems such as (i) wave scattering by a submerged flexible porous plate, (ii) wave trapping by submerged flexible porous plate placed at a finite distance from a rigid wall and (iii) wave reflection by a rigid wall in the presence of a submerged flexible porous plate are analyzed. The role of flexible porous plate in attenuating wave height and creating a tranquility zone is studied by analyzing the reflection, transmission and dissipation coefficients for various wave and structural parameters such as angle of incidence, depth of submergence, plate length, compression force and structural flexibility. In the case of wave trapping, the optimum distance between the porous plate and rigid wall for wave reflection is analyzed in different cases. In addition, effects of various physical parameters on free surface elevation, plate deflection, wave load on the plate and rigid wall are studied. The present approach can be extended to deal with acoustic wave interaction with flexible porous plates.

Particle Creation by Black Holes

Abstract: In the classical theory black holes can only absorb and not emit particles. However it is shown that quantum mechanical effects cause black holes to create and emit particles as if they were hot bodies with temperature\(\frac{{h\kappa }}{{2\pi k}} \approx 10^{ - 6} \left( {\frac{{M_ \odot }}{M}} \right){}^ \circ K\) where κ is the surface gravity of the black hole. This thermal emission leads to a slow decrease in the mass of the black hole and to its eventual disappearance: any primordial black hole of mass less than about 1015 g would have evaporated by now. Although these quantum effects violate the classical law that the area of the event horizon of a black hole cannot decrease, there remains a Generalized Second Law:S+1/4A never decreases whereS is the entropy of matter outside black holes andA is the sum of the surface areas of the event horizons. This shows that gravitational collapse converts the baryons and leptons in the collapsing body into entropy. It is tempting to speculate that this might be the reason why the Universe contains so much entropy per baryon.

Of ocean waves and sea-ice revisited

Abstract: The review of Squire et al. [Squire, V.A., Dugan, J.P., Wadhams, P., Rottier, P.J., Liu, A.K., 1995. Of ocean waves and sea-ice. Annu. Rev. Fluid Mech. 27, 115–168.] is updated to take account of the astonishing surge of activity that has occurred over the last decade or so on topics in the general area of ocean wave/sea-ice interactions, especially in relation to mathematical modelling. Models have become much more sophisticated with the most recent ones allowing the sea-ice to be heterogeneous and the ocean to have variable depth. Pressure ridges, cracks, open and refrozen leads, and gradual or abrupt changes of material property can all be accommodated, and inhomogeneous marginal ice zones can also be effectively modelled. In this paper the author distinguishes between two major sea-ice types: continuous ice, such as is normally found in the central Arctic, and the ice of marginal neighbourhoods, i.e. near the open sea, where individual ice floes and cakes are present at typically lower levels of concentration. The partition is convenient but artificial, of course, as many of the methods employed apply to any kind of sea-ice. A discussion on laboratory and field experiments conducted during the period is also included.

Hydraulic performance and wave loadings of perforated/slotted coastal structures: A review

Abstract: This paper reviews recent progress in the study of perforated/slotted breakwaters, with an emphasis on two main groups of such breakwaters: (1) perforated/slotted breakwaters with impermeable back walls, and (2) perforated/slotted breakwaters without a back-wall. The methods commonly used to simulate the interactions between such structures and various linear/nonlinear waves are summarized. The transmission and reflection characteristics of perforated/slotted breakwaters in these two groups are reviewed extensively. Several methods for calculating wave forces on perforated caissons are also reviewed. Some recent works published in Chinese journals, which are generally not well-known to non-Chinese researchers, are reviewed with a hope that these works can be beneficial to other researchers working in this area.

Review of hydroelasticity theories for global response of marine structures

Abstract: Existing hydroelastic theories are reviewed. The theories are classified into different types: twodimensional linear theory, two-dimensional nonlinear theory, three-dimensional linear theory and three-dimensional nonlinear theory. Applications to analysis of very large floating structures (VLFS) are reviewed and discussed in details. Special emphasis is placed on papers from China and Japan (in native languages) as these papers are not generally publicly known in the rest of the world. q 2005 Elsevier Ltd. All rights reserved.