Wang, Fang (2017-08). Numerical Model of OTRC Wave Basin Based on Linear Hydrodynamics. Master's Thesis. Thesis uri icon

abstract

  • This thesis presents a numerical model of the Offshore Technology Research Center (OTRC) wave basin based on linear hydrodynamics. WAMIT program is used for hydrodynamic analysis. Two methods are explored in simulating the wave basin: (a) build the wave basin model in WAMIT program with tank walls and the pit as a fixed body; (b) simulate the reflection from tank walls using the method of images. In both methods, the wave maker motion is modeled using generalized modes and the higher order panel method is applied. On each panel, the momentum flux is calculated based on third-order Gauss quadratures. The numerical wave basin contains 48 wave maker flaps, side walls, a floor and the wave absorber is modeled as an open boundary. Regular wave response, including the spatial uniformity of the wave field, has been studied. Evanescent modes from the wavemaker, the effect of reflection from a test model and the side walls, and oblique wave generation have also been investigated. It was found that reasonable results cannot be achieved using method (a) of direct side wall modeling despite numerous modifications to the tank geometry and its discretization; most noticeably, spatial uniformity cannot be achieved in long-crested wave generation. On the other hand, method (b) does yield spatial uniformity in long-crested wave generation, to numerical accuracy. Therefore method (b) is adopted for investigation of wave basin responses.
  • This thesis presents a numerical model of the Offshore Technology Research Center (OTRC) wave basin based on linear hydrodynamics. WAMIT program is used for hydrodynamic analysis. Two methods are explored in simulating the wave basin: (a) build the wave basin model in WAMIT program with tank walls and the pit as a fixed body; (b) simulate the reflection from tank walls using the method of images. In both methods, the wave maker motion is modeled using generalized modes and the higher order panel method is applied. On each panel, the momentum flux is calculated based on third-order Gauss quadratures. The numerical wave basin contains 48 wave maker flaps, side walls, a floor and the wave absorber is modeled as an open boundary.

    Regular wave response, including the spatial uniformity of the wave field, has been studied. Evanescent modes from the wavemaker, the effect of reflection from a test model and the side walls, and oblique wave generation have also been investigated. It was found that reasonable results cannot be achieved using method (a) of direct side wall modeling despite numerous modifications to the tank geometry and its discretization; most noticeably, spatial uniformity cannot be achieved in long-crested wave generation. On the other hand, method (b) does yield spatial uniformity in long-crested wave generation, to numerical accuracy. Therefore method (b) is adopted for investigation of wave basin responses.

publication date

  • August 2017