10:30
Theoretical Hydro & Environmental Hydro
Chair: Jiafa Shen
10:30
30 mins
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ENERGY DESCRIPTION OF MOVING DEFORMABLE BODIES THROUGH INVISCID FLUIDS
Ren Sun, Yi Qin
Abstract: The energy-based Lagrangian expressions for multiple deformable bodies translating and rotating through an inviscid fluid are proved to be equivalent to the momentum-type ones using the harmonic function theory. This means the energy description can be used to deal with such hydrodynamic problems with many deformable bodies. In corresponding two-dimensional cases, the equivalence still holds if the kinetic energy expression of fluid is regarded as its nominal kinetic energy, which reveals that the expression is actually an important physical index including all information on hydrodynamic interactions. And those expressions for hydrodynamic loads in complex form derived from the energy description may be transformed into the unsteady Blasius formulae. Moreover, the pressure distribution over the surface of any submerged body is a function of coupled translational, angular and deforming accelerations of all bodies, and therefore masses of all bodies and their mass distributions influence hydrodynamic loads on the body.
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11:00
30 mins
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NUMERICAL MODELLING OF COASTAL PROTECTION BY CORAL REEF USING A CFD MODEL
Inigo Losada, Javier Lara, Maria Maza, Pelayo Menendez
Abstract: One of the most relevant features linked to coastal hazards assessment is the increment of mean water level due to broken waves, called wave setup. In fringing reefs, wave set-up is enhanced inducing larger run-up at the beach. Despite the well known hydrodynamic processes occurring in natural sandy beaches, the role played by bottom vegetation in fringing reefs is very relevant and poorly understood. Although many solutions are used to protect the coast, including artificial man-made structures or natural solutions based on coral reefs or vegetated bottoms, their influence in reducing wave energy needs further analysis. A comparative analysis of different scenarios, such as natural reefs, man-made submerged rubble-mound breakwaters and vegetated reefs, is performed in this work with the aim of demonstrating the ability of vegetated reefs to reduce wave energy at the coastline. The coral reef geometry located in Playa del Carmen (Mexico) has been used as a case study. Single transient wave groups have been analysed. The model called IH2VOF, a Navier-Stokes solver, is used. Results have shown that wave setup and wave run-up are mainly influenced by wave breaking. It has been observed that the more relevant reduction on wave setup and wave run-up is observed when a fore reef is not present. The presence of a vegetated reef has been revealed as an efficient solution, especially for the largest wave height cases, decreasing the wave run-up at the beach.
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