Numerical Simulation Of Wave Resistance Due To Moving Pressure Disturbance

In order to study the hovercraft’s wave resistance over mild slope beach, the hovercraft is simulated as a distribution of pressure source. Based on the projection of the Euler equations on both the free surface and bottom boundary, the general form of Boussinesq equations is taken as governing equations. To solve the time stepping problem, the relationship between the free surface and bottom velocities is established based on the series solution of Laplace equation. Therefore the governing equations are closed. Free surface elevation due to fast moving pressure distributions is solved with the Boussinesq equations in water of finite depth. The velocities at the half water depth is chosen as one of the basic variables in the Boussinesq equations. By adding moving pressure source term in the dynamics boundary condition at free surface, we can simulate the ship waves and then calculate the wave resistance.In this thesis, the magnitudes of wave resistance over flat and mild slope topography are predicted using the proposed method.For flat bottom problem, the pressure disturbance moves suddenly, leading to a rapid changing of resistance coefficient at first, then the coefficient become steady finally. The variations of resistant coefficient versus different Fr number are studied.For wave resistance over mild slope, the resistant coefficient decrease fast versus Fr number in super-critical flow region, i.e. Fr number is greater than1.06and less than1.30. When the Fr number is greater than1.30, the resistance increases versus Fr number. In trans-critical flow region, the wave resistance reaches a maximum value. Significant difference of wave resistance between pressure sources’moving over flat and mild slope beaches is found.