Hydrodynamics, control and numerical modelling of absorbing wavemakers
Hydrodynamics, control and numerical modelling of absorbing wavemakers
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吸波造波机的流体动力学、控制和数值模拟
DOI：
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发表时间：
2011
期刊：
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通讯作者：
A. E. Maguire
中科院分区：
文献类型：
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作者：
A. E. Maguire
这项研究调查了几何形状和控制对有源造波机吸收特性的影响，并着眼于在商业计算流体动力学软件中模拟这些造波机的可行性。本文给出了四种不同类型造波机的水动力系数。用不同的控制阻抗系数组合分析了这些造波机的吸收特性。然后研究了几何和控制相结合的影响。结果，给出了吸收特性的量化。结果表明，对于给定的桨叶，不同的控制系数的选择对实现复共轭控制有很大的不同。当造波机的几何形状针对一个特定频率进行优化，而控制阻抗针对另一个频率进行优化时，可以在更宽的频率带宽上实现更大的吸收。结合这一理论研究，进行了数值研究，以验证和验证两个商业计算流体动力学程序对模拟前面讨论的吸收波造波装置的适用性。利用有限元分析软件Ansys、CFX和FLOW3D对物理造波机进行了建模。两者都经过了严格的离散化误差验证，CFX也根据线性造波理论进行了验证。结果表明，接近振荡器的自由面具有很好的一致性和预测性，但遇到了波高衰减和运行时间过长的问题。
This research investigates the effects that geometry and control have on the absorption characteristics of active wavemakers and looks at the feasibility of modelling these wavemakers in commercial computational fluid dynamic software. This thesis presents the hydrodynamic coefficients for four different types of wavemakers. The absorption characteristics of these wavemakers are analysed using different combinations of control impedance coefficients. The effect of combining both geometry and control is then investigated. Results, quantifying the absorption characteristics are then presented. It is shown that the amount of absorption for a given paddle differs greatly depending on the choice of control coefficients used to implement complex conjugate control. Increased absorption can be achieved over a broader bandwidth of frequencies when the geometry of the wavemaker is optimised for one specific frequency and the control impedance is optimised for an alternate frequency. In conjunction to this theoretical study, a numerical investigation is conducted in order to verify and validate two commercial computational fluid dynamic codes’ suitability to model the previously discussed absorbing wavemakers. ANSYS CFX and FLOW3D are used to model a physical wavemaker. Both are rigorously verified for discretisation errors and CFX is validated against linear wavemaker theory. Results show good agreement and prediction of the free surface close to the oscillating wavemaker, but problems with wave height attenuation and excessive run times were encountered.