Numerical Simulation of Hydrodynamic Behaviors of Gravity Cage in Waves

This paper aims at investigation of the dynamic properties of gravity cage exposed to waves by use of a numerical model. The numerical model is developed, based on lumped mass method to set up the equations of motion of the whole cage; meanwhile the solutions of equations are solved by the Runge-Kutta-Verner fifth-order and sixth-order method. Physical model tests have been carried out to examine the validity of the numerical model. The results by the numerical simulation agree well with the experimental data.     

亚铁还原-钒酸铵滴定法测定矿石中铀的改进(铁粉还原-钒酸铵滴定法)

在磷酸介质中对铀的还原反应,铁粉比亚铁离子具有更高的还原能力。 Fe~2+2e=Fe,E~0=-0.409伏。当H_3PO_4浓度达7.090M时, Fe~3+e=Fe~(2+),E~0=0.448伏, 此时的 UO~(2+)_2+4H~++2e=U~(4+)+2H_2O,E~0=0.595伏。根据氧化-还原电位次序,在磷酸介质中铁粉和亚铁都能还原铀(Ⅵ),但铁粉还原能力强,且生成的亚铁又可以还原铀(Ⅵ),一个F~o_c相当于3个Fe~(2+)的电子失掉的还原剂作用。经研究实验铁粉用量为0.02—0.03克,比用亚铁还原法的莫尔盐中亚铁量0.048—     

应用Boussinesq方程对由航道开挖所造成水深变化对波浪传播所产生的异常波况的数值研究

应用Boussinesq方程采用有限差分法建立了非线性数值波浪模式，并应用该模式对由航道开挖所造成水深变化对波浪传播产生的异常现象进行了数值模拟研究。从结果来看这种异常波浪局部增大现象是由于入射波与航道夹角过小，使波浪无法折射入航道，而在航道两侧反射叠加的结果。因此说水深的变化对波浪产生的反射现象也是不可忽视的。     

缓坡上波浪谱的变形及破碎

在文献[1]中,通过实验分析和理论计算,笔者提出不规则波浪的破碎指标仍可采用合田^[2]的相对波高极值(H/d)_b与Michell^[3]和Miche^[4]的极限波陡指标(H/L)_b.本文利用该破碎指标,分析计算了缓坡上不规则波在水流作用下的谱变形、波高的统计分布以及波浪破碎的概率等,其结果与作者的实验结果符合良好。     

不规则波和流作用于圆柱上的正向力及横向力

本文研究了垂直圆柱体在稳定流与不规则波共同作用下的受力问题,给出了适用于这一流场下KC数的定义.本文利用Morison方程分析桩柱在不规则波和流共存场中受力的计算,给出了速度力系数C_d、惯性力系数C_m及横向力系数(C_L)_max及(C_L)_1/3随KC数的变化情况.本文还探讨了波流联合作用下横向力与合力特征值和正向力特征值的关系.     

Numerical analysis of hydrodynamic behaviors of two net cages with grid mooring system under wave action

Based on rigid kinematics theory and lumped mass method,a mathematical model of the two net cages of grid mooring system under waves is developed.In order to verify the numerical model,a series of physical model tests have been carried out.According to the comparisons between the simulated and the experimental results,it can be found that the simulated and the experimental results agree well in each wave condition.Then,the forces on the mooring lines and the floating collar movement are calculated under different wave conditions.Numerical results show that under the same condition,the forces on the bridle ropes are the largest,followed by forces on the main ropes and the grid ropes.The horizontal and the vertical float collar motion amplitudes increase with the increase of wave height,while the relationship of the horizontal motion amplitude and the wave period is indistinct.The vertical motion amplitude of the two cages is almost the same,while on the respect of horizontal motion amplitude,cage B(behind cage A,as shown in Fig.4) moves much farther than cage A under the same wave condition.The inclination angle of the floating system both in clockwise along y axis and the counter one enlarges a little with the increase of wave height.     

浙江沿海超强台风作用下风暴潮增水数值分析

基于河口海岸水动力二维数值模型,建立风暴潮与天文潮耦合作用的数值模式,通过三次强台风和二次超强台风引起的风暴潮增水模拟和分析,证实该模式可用于浙江沿海增水预测.以1949年以来登陆我国大陆沿海最强的"5612"号台风作为典型的超强台风,利用本模式计算分析了超强台风在浙北至浙南5个不同地点登陆遭遇大潮时可能出现的风暴潮增水过程和最大增水,该结果对于海岸工程的防护具有实际的意义.     

斜向波与带填料开孔板式防波堤相互作用的研究

基于线性势流理论,对斜向波与消浪室内带部分填料的开孔板式防波堤结构的相互作用进行了理论研究.利用匹配特征函数展开法给出了开孔防波堤结构反射系数和波浪力系数的理论计算方法,在极限情况下的计算结果与已有结果一致.利用数值算例分析了开孔结构反射系数和波浪力系数的主要影响因素.增加消浪室内填料厚度通常可以降低开孔墙结构的波浪力系数,加大结构的反射系数.随着波浪入射角度的增加,带填料防波堤结构的反射系数值先减小,达到最小值后又单调增加.