渤海海冰动力学的质点网格法数值模拟

为准确计算渤海海冰的动力过程，本文将质点网格方法(Particle—in—cell，简称PIC)，引入到渤海海冰数值模拟中。该方法首先在欧拉坐标系下对海冰动力方程和连续方程进行差分求解，并插值出各网格内海冰质点的速度和密集度，然后在拉格朗日坐标系下对海冰质点的位移和各网格的平均冰厚进行确定。PIC方法将欧拉法与拉格朗日法相结合，避免了欧拉坐标下有限差分法的数值扩散和拉格朗日坐标下光滑质点流体动力学计算量大的缺点。在对渤海海冰动力过程的数值模拟中采用了Hibler的粘塑性本构模型，并考虑了海冰热力作用过程。利用PIC方法对辽东湾海冰进行了48h数值模拟，结果表明：该方法可成功地处理海冰流变过程，精确计算出冰缘线位置和海冰分布状况，对海冰厚度和密集度的计算精度均优于有限差分法。PIC方法在精确模拟海冰的重叠和堆积过程，以及为冰区油气作业提供详实的海冰信息方面都有良好的应用前景。     

斜坡式防波堤前海冰堆积数值模拟

本文将海冰在斜坡式防波堤前的堆积过程简化为二维的动力学问题，假定海冰为粘弹性体，在多边块体运动模拟系统基础上，采用离散元数值方法对冰排爬升堆积过程进行了实时仿真模拟。通过与二维理论断裂模型及物理模型试验结果对比，证明了此数值模型的合理性与可行性。     

波浪对渤海近岸海冰冲击作用的数值模拟

海冰在波浪冲击作用下可能会发生断裂,通过数值模拟定量地描述波浪引起的海冰断裂对海工结构的运行安全以及分析海冰断裂处海水与大气之间的热交换有重要作用。该文利用建立的三维数值波浪水池,将海冰视为刚性平板,结合渤海冬季海冰、波浪的相关参数,研究海冰受波浪冲击的垂向冲击力、水平冲击力、弯矩和最大弯曲正应力随波高、冰长及冰厚的变化规律;并结合渤海海冰的弯曲强度,推断海冰发生断裂的极限参数,结果表明:在渤海海域某些特定条件下,海冰断裂极限波高、冰长和最小冰厚分别为0.504 m、4.273 m和0.098 m。     

ANSYS在隧道衬砌结构分析中的应用

根据局部变形理论，把隧道衬砌简化成合理的计算力学模型，在ANSYS数值模拟环境中，按边值法的分析思路，对其进行结构分析。该数值分析结果已得到了边值法验证，是可行的。     

数值切割单元法在河流数值模型中的应用前景展望

天然地表水边界复杂,且处于不断的冲淤变化中。数值切割单元法可任意追踪拟合复杂动边界,且网格生成简单,在计算流体中具有重要的研究和应用价值。本文对数值切割单元法常用的直接插值法、虚源反射法和直接源项法的基本原理、适用条件及关键难点解决方面等进行了系统总结。结合地表水流的动力特性,给出数值切割法在复杂边界地表水模拟中的具体应用方法,提出在二维模拟中,可直接采用基于有限体积法的直接插值法进行数值切割,而在三维模拟中,联合采用sigma-网格及直接源项法可同时实现模型的准确性及高效性。最后,通过对比目前数值切割法在其它领域典型算例,提出数值切割单元法在崩岸、河工建筑和植物绕流模拟、高精度紊流模拟等地表水模型难题方面的应用前景。     

考虑涌潮作用的钱塘江二维泥沙输移数值模拟

钱塘江涌潮前后水位、流速和含沙量等物理量存在突变，给数值模拟带来了很大的困难，传统的数值模型往往不能准确模拟涌潮作用下的泥沙输移。在已建立的二维涌潮数值模型的基础上，应用基于准确Riemann解的Godunov格式建立了二维泥沙数值模型，模型首先检验了纯对流问题，然后模拟了钱塘江涌潮作用下的泥沙输移，计算结果反映了涌潮到达时刻含沙量的突变过程以及涌潮对泥沙输移的影响，揭示了钱塘江河口高含沙量区成因，以及涌潮是钱塘江河口大冲大淤的机理之一。     

基于弱可压缩理论的射流泵流场数值预报

应用弱可压缩流体控制方程和大涡模拟湍流模型，采用MacCormack的预估一校正方法对射流泵内流场(二维)进行了数值模拟。经过对不同射流泵运行工况的计算，都取得了令人满意的预报结果。研究表明，弱可压缩流动方程能代表低马赫数时的真实流动现象，且方程具有双曲性质易于数值求解。数值模拟结果可为改进射流泵性能提供依据。     

基于ＡＢＡＱＵＳ生死单元技术的平衡地应力方法研究

初始地应力是岩土工程数值模拟过程中必不可少的一部分，其初始地应力平衡效果的好坏对后续的数值分析有着较为显著的影响。通用有限元软件ＡＢＡＱＵＳ虽然提供了多种地应力平衡方法，但是岩土工程材料多样、工况复杂，并不是所有的常规方法都能使地应力平衡满足要求。针对压硬性砂土地基中桶土相互作用问题，通过二次开发，对于ＡＢＡＱＵＳ软件中的Ｍｏｈｒ-Ｃｏｕｌｏｍｂ弹塑性本构模型进行改进，从而可以考虑砂土中变形模量随平均主应力变化的压力相关性。进而基于软件中生死单元功能，提出了一种分步平衡法，通过分步创建桶土之间的接触以更好地模拟地基在桶土相互作用过程中的实际响应。结果表明，分步平衡法的地应力平衡效果明显优于常规自动平衡法，可为其他类似模拟提供参考价值。     

基于分层法的水工混凝土碳化过程有限元模拟

碳化是影响水工混凝土耐久性的重要因素。根据混凝土中CO_2扩散方程与热传导方程的对等性,借助ANSYS有限元软件中热传导模块对水工混凝土碳化过程进行数值模拟。针对工程实际中混凝土内部水灰比存在差异的情况,采用分层法建立数值模型。通过对比碳化深度的数值模拟值与室内快速碳化试验值,证明该数值模型能较好地模拟混凝土中CO_2的扩散过程,可为碳化混凝土的寿命预测提供参考。     

淮河干流淮南段二维水质模拟

利用二维水质模型，基于交替方向法（ADI法）对模型进行离散求解，结合面向对象的MATLAB高级编程语言，编制了水质模型计算程序，对淮河干流淮南段（鲁台子至田家庵河段）的污染物浓度场进行了数值模拟；并利用MATLAB的图形可视化技术，对水质模型数值模拟结果进行了图形化处理。经模型验证，模拟结果与该段河流的实际水质监测结果基本吻合。     

MEASURING SEA ICE DRIFT VIA CROSS-CORRELATION OF RADAR ICE IMAGES

The motion of sea ice has a great effect on winter navigation, and oil field exploration in the Bohai Sea. It is very important to measure the ice drift accurately and efficiently. As a practical technique, radar imagery has been used for sea ice monitoring and forecasting for a long time. Combining with the radar imagery and cross-correlation technique, a new measurement method based on the cross-correlation of radar ice images is specified in this paper to obtain full field measurement of sea ice drift. The theory and fast implementation of cross-correlation are presented briefly in the paper, ineluding the filtering method to modify the invalid vectors. To show deeply the validity of the present method, the velocity maps of sea ice drift are provided in the paper, which are calculated from the radar images grabbed in the Liaodong Gulf.The comparison with the traditional tracing method is also conducted.     

NUMERICAL SIMULATIONS OF SEA ICE WITH DIFFERENT ADVEC- TION SCHEMES

Numerical simulations are carried out for sea ice with four different advection schemes to study their effects on the simulation results.The sea ice model employed here is the Sea Ice Simulator(SIS) of the Geophysical Fluid Dynamics Laboratory(GFDL) Modular Ocean Model version 4b(MOM4b) and the four advection schemes are,the upwind scheme originally used in the SIS,the Multi-Dimensional Positive Advection(MDPA) scheme,the Incremental Remapping Scheme(IRS) and the Two Step Shape Preserving(TSSP) scheme.The latter three schemes are newly introduced.To consider the interactions between sea ice and ocean,a mixed layer ocean model is introduced and coupled to the SIS.The coupled model uses a tri-polar coordinate with 120×65 grids,covering the whole earth globe,in the horizontal plane.Simulation results in the northern high latitudes are analyzed.In all simulations,the model reproduces the seasonal variation of sea ice in the northern high latitudes well.Compared with the results from the observation,the sea ice model produces some extra sea ice coverage in the Greenland Sea and Barents Sea in winter due to the exclusion of ocean current effects and the smaller simulated sea ice thickness in the Arctic basin.There are similar features among the results obtained with the introduced three advection schemes.The simulated sea ice thickness with the three newly introduced schemes are all smaller than that of the upwind scheme and the simulated sea ice velocities of movement are all smaller than that of the upwind scheme.There are more similarities shared in the results obtained with the MPDA and TSSP schemes.     

沧州渤海新区海冰资源开发利用的可行性分析

京津冀协同发展战略及河北省沿海地区发展规划的提出,促进了环渤海经济圈的发展,沧州渤海新区地处环渤海经济圈的核心地带,城市化进程不断加快,使得水资源需求变大,加重了水资源短缺的形势。本文通过分析、统计新区的气象、水量及规划数据,计算了沧州渤海新区的供需水量。结果表明:到2020年需水量约为4.03×10~8m~3/a,预期可供水约3.27×10~8m~3/a,水资源缺口近7600×10~8m~3/a。运用ENVI软件解译黄骅海域的遥感影像,预期新区可开采海冰量约为1.76×10~8m~3,供水约为8 800×10~8m~3/a。因此,沧州渤海新区的海冰储量可观、淡化成本低、水质好,淡化水可替代生态及部分工业用水,海冰资源的开发利用的前景广阔,可行性高。在新区内尝试开发利用海冰资源不仅可以减轻灾害损失,缓解水资源短缺问题,还为我国其他饱受海冰灾害影响的沿海地区提供参考和指导。     

EXPERIMENTS OF SEA ICE SIMULATION

As a substitute for the original displaced pole grids, a simple rotated spherical coordinate system was intro duced into the Community Sea Ice Model version 4（CSIM4）, which is a component of the Community Climate System Model（CCSM） of the American National Center of Atmospheric Researeh（NCAR）, to deal with the ＂pole problems＂. In the new coordinates, both the geographical North Pole and South Pole lie in the model equator and grid sizes near the polar region are more uniform. With reanalysis dataset of American National Centers for Environment Prediction （NCEP） and Levitus dataset without considering sub-mixed layer heat flux, the model was integrated for 100 years with thermodynamics proce.ss involved only in the former 49 years and both dynamic and thermodynamic processes involved in the left time. Inner consistency of model results was checked with no contradiction found. The results of last 10 years＇ model output were analyzed and it is shown that the simulated sea ice seasonal variation is rational whereas sea ice extent in the Barcnts Sea in winter is larger than that of observation, Numerical experiment on influence of sub-mixed layer heat flux was also carried out and it is shown that the sub-mixed layer heat flux can modulate seasonal variation of sea ice greatly. As a model component, the sea ice model with rotated spherical coordinates was coupled with other models （the oceanic general cir culation model is the LASG/IAP Climate System Ocean Model （LICOM） with reduced grid, other models are components of NCAR CCSM2） forming a climate system model and its preliminary results were also given briefly.     

MODEL OF SEA ICE BREAKUP ON SHALLOW BEACH DUE TO TIDAL FLUCTUATION

1.　 INTRODUCTIONThe breakup ofice isthe basis to analyze the mechanism of ice ride-up and pile-up,andto further study the formation of rafted ice and ice ridge.Up till now,researcheshave focused on the effectof wind and currenton shore fasticebreakup.Christensen F.T.[1 ] analyzed the possible size ofthe ice pieces when the ice floe in-teracts with the slope underthe action of wind and currentdriving forces.S rensen C.[3] in-vestigated the failure of a floating ice floe when itcollided w…     

新疆输水工程冰害防治研究与展望

新疆地处中国西北部,其特殊的气候、地理及水文特征,导致输水工程出现严重的冰害问题。该文概括地阐述了新疆输水工程产生冰害的原因,以及冰害在输水建筑物渠首、渠道表现出的不同冰害类型。提出了修建蓄冰库、结冰盖运行、增加水温或增加压力水射流融冰、输冰以及排冰等工程技术措施。目前取得的防治冰害的工程技术措施,基本满足近期冰害的防治问题,但随着新疆大规模调水工程的实施,输水工程冰害的防治问题不可忽视,水利科技工作者面临着新的冰害防治问题需要研究。     

水内冰冰塞堆积演变的研究

本文根据黄河河曲段六年的冰情资料，分析研究了该河段冰塞演变及冰期水位变化的规律，建立了冰塞运动有关参数的关系式，在此基础上，对实验室模拟冰塞的运动进行了分析研究。研究表明：实验室模拟冰塞的演变规律与天然冰塞的演变规律相似。