波流干扰下深水畸形波成因和演化的数值模拟研究

发布时间：2018-06-06 16:28

本文选题：深水畸形波 + 波流干扰　；参考：《上海交通大学》2014年硕士论文

【摘要】：畸形波因为其破坏性强、出现没有前兆等特点，对于船舶海洋工程有重大的工程研究意义；同时，虽然已经有几种理论可以解释畸形波的产生，其机理仍不明确，具有一定的理论研究价值。另外，实海中，波流相互干扰是不可忽视的因素，流的存在会对波浪的参数、传播和形状产生重要的影响，逆流也被认为是畸形波的重要成因之一，故流对畸形波的影响也是不可忽视的。本文基于粘性模型，着眼于色散关系引起的波浪聚焦而产生的畸形波，探讨畸形波生成原理和演化过程，数值模拟畸形波的生成和演化以及讨论波流干扰对畸形波的影响是本文的两个主要部分。本文的主要研究内容包括：1）基于RANS方程和RNG k-ε湍流模型，并用VOF方法处理自由表面，生成流作用下的规则波。2）进行规则波的循环水槽实验，验证规则波的生成以及它和均匀顺流的相互作用，建立了可靠的数值水槽。3）讨论顺流和逆流对于规则波影响，除了对波浪要素的变化进行了定量讨论，对逆流中出现的波陡升高、波浪不对称性加剧、波浪破碎和波浪堵塞现象进行了详细研究。4）基于建立的数值水槽，运用过渡水波理论生成畸形波，研究了顺流和逆流对于畸形波的影响，并和基于四阶非线性薛定谔（NLS）方程的模拟结果进行比较，讨论了粘性流下畸形波的机理。主要结论有：1）流对于波浪要素的影响和既往研究结论一致，即：顺流中波高和波陡会变小，，逆流会增加波浪的波高和波陡。2）粘性模型在预测波高的变化时准确性更好。3）逆流会使得波浪波峰变尖，不对称性加剧，时有波浪破碎发生。4）当逆流速度接近波群速时，会出现波浪堵塞现象，波流之间出现强烈的能量转换。5）粘性模型预测的畸形波聚焦时间和势流理论相比要晚，在实验中应该充分考虑这一因素。6）流的存在会加剧畸形波的不对称性，且粘性模型和势流理论预测的变化规律存在差异。7）顺流中畸形波聚焦更快，逆流中聚焦更慢。8）逆流会加剧畸形波的破碎现象。
[Abstract]:Because of its destructive and no precursor characteristics, the deformable wave has great engineering significance for marine engineering. At the same time, although there are several theories to explain the formation of the deformed wave, its mechanism is still unclear. It has certain theoretical research value. In addition, in the real sea, the interaction of waves and currents is an important factor that can not be ignored. The existence of currents will have an important impact on the parameters, propagation and shape of waves, and countercurrent is also considered to be one of the important causes of abnormal waves. Therefore, the effect of the current on the abnormal wave can not be ignored. In this paper, based on the viscous model, the formation principle and evolution process of the wave focusing caused by dispersion relation are discussed. Numerical simulation of the generation and evolution of deformable waves and discussion of the effects of wave and current interference on deformities are two main parts of this paper. The main research contents of this paper include: (1) based on RANS equation and RNG k- 蔚 turbulence model, the regular wave of regular wave is generated by using VOF method to treat free surface. To verify the generation of regular wave and its interaction with uniform forward current, a reliable numerical tank. 3) to discuss the influence of forward current and countercurrent on regular wave, except for the change of wave elements, is discussed quantitatively. In this paper, the phenomena of wave rise, wave asymmetry, wave breakage and wave blockage in countercurrent are studied in detail. Based on the established numerical flume, the transient water wave theory is used to generate deformed waves. The effects of downstream and countercurrent on the deformable waves are studied and compared with the simulation results based on the fourth-order nonlinear Schrodinger (NLS) equation. The mechanism of the deformities under viscous flow is discussed. The main conclusion is that the effect of the current on the wave elements is consistent with previous studies, that is, the wave height and steepness in the downstream flow will become smaller. The inverse current will increase the wave height and wave steep.2.) the viscosity model is more accurate in predicting the variation of wave height. 3) the countercurrent will make the wave peak sharpen, asymmetry intensifies, and wave fragmentation occurs. 4) when the countercurrent velocity approaches the wave group velocity, The phenomenon of wave blockage will occur, and there will be a strong energy conversion between waves and currents. 5) the focusing time of deformed waves predicted by viscous model is later than that of potential flow theory. In the experiment, the existence of this factor. 6) flow will aggravate the asymmetry of the deformed wave, and there is a difference between the viscosity model and the potential flow theory. 7) in the downstream flow, the deformity wave focuses more quickly. In the countercurrent, the focusing is slower. 8) the countercurrent will aggravate the fragmentation of the deformed waves.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.22

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