Antarctic ice sheet GLIMMER model test and its simplified model on 2-dimensional ice flow

The 3-dimensional finite difference thermodynamic coupled model on Antarctic ice sheet, GLIMMER model, is described. An idealized ice sheet numerical test was conducted under the EISMINT-1 benchmark, and the characteristic curves of ice sheets under steady state were obtained. Based on this, this model was simplified from a 3-dimensional one to 2-dimensional one. Improvement of the difference method and coordinate system was proposed. Evolution of the 2-dimensional ice flow was simulated under coupled temperature field conditions. The results showed that the characteristic curves deriving from the conservation of the mass, momentum and energy agree with the results of ice sheet profile simulated with GLIMMER model and with the theoretical results. The application prospect of the simplified 2-dimensional ice flow model to simulate the relation of age-depth-accumulation in Dome A region was discussed.     

河流冰盖热力增长的数值模拟

文章基于多相流理论,建立了河流的热力与水力条件耦合的二维河道模型.模型把河流当作大气-冰体-水体的一个耦合系统,考虑了系统中界面的热量交换,并考虑了冰花在冰盖下堆积对冰盖热量交换的影响.在不同的入口冰花浓度、冰盖上表面温度、入口水流速度的工况下,对冰盖的增长进行了模拟分析,获得了冰盖厚度的增长特征与冰盖形成后水体速度场和温度场的分布特征.模拟结果表明:入口冰花浓度越大、冰盖上表面温度越低、入口流速越小,则形成的冰盖厚度越大;断面上的流速越大,水温越低.     

Preliminary results of ice radar investigation along the traverse between Zhongshan and Dome A in East Antarctic ice sheet: Ice thickness and subglacial topography

During the 24th Chinese National Antarctic Research Expedition (CHINARE 24, 2007/08), a ground-based ice radar was used to survey ice thickness and subglacial topography along the 1170 km traverse between Zhongshan and Dome A in East Antarctic ice sheet (EAIS). Ice-bedrock interface was detected along 82% of the traverse and data was collected at a horizontal resolution of <5.6 m. The data was processed to produce curves of ice thickness distribution and subglacial topography along the traverse. The results indicate that, along the traverse, the average ice thickness is 2037 m, smaller than the average ice thickness in EAIS; the thickest ice is at 730 km, and the thinnest ice (891 m) is at the edge of the ice sheet, but the slightly larger ice thickness (1078 m) in inland appears at 1020 km; the average subglacial topography elevation is 728 m, greatly larger than the average value in EAIS, and the largest elevation reaches up to 2650 m at 1034 km. The lowest terrain is located at 765 km. In further inland of 900–1170 km, the subglacial topography is relatively high due to the existence of the Gamburtsev Subglacial Mountains in the region. Generally, the influence of subglacial topography on ice surface is not significant, except at 900 km where great rise of subglacial topography causes evident uplift of ice surface. Where ice-bedrock interface was detected, the frequent and strong change of ice thickness and subglacial topography in small-scale means large bedrock roughness along the traverse, and is considered as the result of the integrated influence of ice flow, basal environments and geology. The segment where bedrock was not detected has very large ice thickness. The strong ice flow there also makes internal structure more complicated and induces serious attenuation of radar signals.     

冰盖下组合桥墩的局部冲刷特性及水力特性

为研究冰盖对组合桥墩局部冲刷及其周围流场分布的影响,基于动床冲刷试验,在不同覆盖条件下,分析了不同水流条件和桥墩尺寸对组合桥墩局部冲刷的影响,建立了预测明渠水流与冰盖流条件下组合桥墩最大冲刷深度的经验方程,并通过ADV测量了墩前的流场。结果表明:组合桥墩的冲刷模式与串列桥墩相似,最大冲刷深度始终出现在墩正前方;经验方程中来流水深、来流流速、桥墩尺寸、冰盖糙率均与最大冲刷深度呈正相关关系;在粗糙冰冰盖流条件下,墩前的垂向流速最大,导致其最大冲刷深度总是大于同等条件下的明渠水流和光滑冰盖流。     

冰雪条件下城市道路路段车头时距

为准确把握冰雪条件下城市道路交通流特性,研究城市不同类别道路的车头时距分布规律,在大量实地调查数据的基础上,对冰雪条件下,城市不同等级道路上的车头时距进行数据整理、分析。采用爱尔朗分布拟合不同条件下的车头时距分布,并进行检验。结果表明拟合效果良好。为冰雪条件下城市道路交通流特性研究提供理论及数据基础。     

不同破坏模式下锥体结构冰力定性分析

采用弹性基础板模型,对锥体结构上冰破坏力随不同弯曲破坏模式而变化的关系进行了定性分析,给出了由2个尺寸比表达的与3种破坏模式相对应的冰荷载表达式和1个由尺寸比定义的破坏模式图.利用这一结果揭示了弯曲破坏冰力幅值与周期大幅度变化的力学机理.板型弯曲破坏冰力是尺寸比k1的减函数;楔梁型破坏冰力是k1的增函数.这预示着最大冰力将在两种破坏模式过渡时出现.冰力周期随冰的断裂长度与其厚度之比k2增大而增长,当k2大于5时,破坏模式由板型过渡到楔梁型.该结果可在现场数据分类识别和冰力速度效应的定性分析等方面得到应用.     

冰与混凝土坝坡间的冻结强度模拟试验

根据实际水库观测冰盖与护坡的冻结情况，在实验室内进行模拟水库冰盖与护坡局部断面的冻结试验．采用冰与混凝土板间的冻结，进行一次冻结、多次冻结、冰晶冻结、雪冰冻结等模式．分析出冰压力与冻结力的关系；在不同温度下测得各种冻结情况中的冻结强度，给出冻结强度随着温度变化的规律和数值．其结果为寒区平原水库坝坡抵抗冰推力破坏提供了设计参数．     

冬季引水明渠冰盖生长的数值模拟

冬季寒区引水明渠的结冰问题会影响河道的运行和管理,文章利用热力和水力耦合的数学模型对不同条件下二维渠道内的冰盖生长进行数值模拟,通过改变水流速度、气温、水深以及风速的大小分析形成的冰盖厚度;根据数值模拟结果,得出了寒区引水明渠冰盖厚度的增长规律与冰盖形成后水流速度场和温度场的分布规律,以及不同因素对渠道结冰的影响程度.     

窄锥结构冰力分析

为了满足窄锥结构动冰力函数构造的需要,提出了一个新的锥体结构冰力计算公式,公式由体现锥角效应、接触宽度效应和冰断裂长度效应三参数表达,它能够合理地反映冰力幅值与作用周期的相关关系。算例结果与几个有影响力的经验公式和理论公式的比较显示,新公式能更好地模拟结构的实际冰力。     

细粒酒精模型冰的物理性质研究

依据实测数据 ,给出酒精溶液冻结温度和制冰过程中冰池大厅气温、冰表面附近气温、冰温和溶液温度 .介绍模型冰密度、冰内未冻液体含量的实测方法和结果 .得出模型冰物理性质的制约因素和力学性质不受冰温控制的推论     

平衡冰塞厚度与水流条件和冰流量关系的试验研究

平衡冰塞出现时河道冰塞的厚度最大，它是冰塞发展过程中的一个重要阶段，又是开河冰塞的前期基础，对于凌洪灾害、冬季河床演变具有重要的影响。本文通过水槽试验，对平衡冰塞的形成与变化机理进行了试验研究，揭示了平衡冰塞厚度与冰流量及水流条件等因素间的相互关系，依据试验资料定性得出了平衡冰塞厚度计算的表达式，并分析了影响平衡时间的一些因素。     

Investigation of electron transfer across the ice/liquid interface by scanning electro- chemical microscopy

Charge transfer across a liquid/liquid (L/L) interface is not only related to chemical sensors, drug delivery and phase transfer catalysis, but also significant for mimicking biological membranes[1—3]. The thermodynamics, kinetics and mechanism regarding of this type of heterogeneous transfer process have been intensively investigated in the past three decades. An external potential is usually applied to polarizing the interface in the case of conventional electrochemistry at L/L interfaces.…     

机翼表面结冰数值模拟

分别采用欧拉-拉格朗日模型和多孔介质模型建立了空气绕流机翼流动、空气夹带过冷水滴运动和机翼表面冰层增长的数理模型,并进行了数值求解.获得空气绕流机翼流场、空气夹带的过冷水滴运动轨迹、机翼表面过冷水滴的收集系数分布、冰层厚度分布和冰层质量增长情况,并分析了攻角和过冷水滴直径等因素的影响.结果表明:水滴收集系数随着攻角和水滴平均直径的增大而增大;冰层覆盖整个机翼的前半部上下表面,以驻点附近最为集中,随时间增长而愈严重;随着功角增大,下表面积冰加重;但当攻角为15°时,总体结冰量却较之低攻角时减小.     

淡水冰导温系数参数识别的应用

利用识别得到的淡水冰导温系数依赖于冰温的变化关系式,模拟山西太原汾河二库淡水冰温度场的变化情况.使用导温系数经验常数模拟同一水库温度场的变化情况.经过比较得出:依赖于冰温变化的淡水冰导温系数更符合实际.     

Estimation of components of energy balance on drifting ice over Arctic Ocean

Estimation and simulation were carried out for the components of ice-surface energy balance and tur bulent exchange parameters using the flux-profile method and the sinple biosphere model version 2 (SiB2, hereinafter) respectively based on the measured results for the atmosphere in the near-ice-surface layer, which were observed by the First Arctic Scientific Expedition of China in August, 1999 at a joint ice-research station (75°02′N, 160°51′W) on the drifting ice of Arctic Ocean. Evidence suggests that during the melting period of drifting ice the sum of the ice-released sensible heat and effective melting-consumed heat is greater than the net ice-absorbed radiation on the surface, with the excess heat coming via heat conduction from the deep layers of the ice mass. The simulated net radiation is systematical lv 18% greater than the measured results, while the simulated sensible heat flux is systematically 3% lower than the measured ones; and the simulated ice-surface heat flux differs noticeably from its calculation. Hence, we see that al though the measured sequences are short, the simulations of net radiation and sensible heat fluxes by the SiB2 model are comparatively good, the simulation of other forms of fluxes still needs to be improved.     

基于SPH方法的渤海海冰动力学数值模拟

简要介绍了光滑质点流体动力学 (smoothed particle hydrodynamics,简称SPH) 方法的基本原理,并将此方法应用到渤海海冰动力学数值模拟中. 在对海冰动力学方程和粘弹塑性本构方程进行SPH处理的基础上,对渤海海冰的动力演化过程进行了48 h的数值模拟,得到了海冰厚度、密集度、速度和主应力的演化过程及分布规律,同时对模拟的海冰厚度等值线分布与卫星遥感图像进行了对比分析. 数值模拟结果表明,SPH能够精确地模拟海冰分布规律以及冰缘线的位置,具有很高的计算精度和稳定性,是一种有效的海冰动力学数值模拟方法.     

气垫船兴波破冰问题的数值计算

将求解船舶兴波问题的Rankine源数值计算方法推广应用到水面边界条件为碎冰面、纯冰面和半冰面-半水面等气垫船破冰中不同类型的兴波问题.对不同类型兴波问题采用统一形式的基本方程,通过面元法与有限差分法相结合的方法对方程进行数值离散.重点对气垫船在全冰面、半冰面-半水面上运动时的兴波进行了数值计算,兴波阻力和波形等计算结果与相关文献符合较好.     

考虑脱冰速度效应的输电线路脱冰模拟

输电线路的脱冰将对相邻塔产生纵向不平衡张力,严重威胁到输电线路的安全。提出输电线覆冰脱落的有限元模拟方法,与以往的模型试验结果进行比较以验证该方法的准确性,分析导线和地线整档同时脱冰产生的系统响应,最后针对导线的unzipping形式脱冰分析脱冰速度对响应的影响。本文的算例发现,地线整档同时脱冰将产生比导线整档脱冰更大的纵向不平衡张力。在unzipping形式脱冰分析中,脱冰速度越慢,系统响应越接近于静态卸载;脱冰速度越快,系统响应越接近于整档同时脱冰。     

雷暴云中冰晶粒子对电磁波的极化作用

为了研究雷暴云中冰晶粒子在带电情况下对电磁波传播的影响,利用冰晶粒子的介电常数模型和瑞利近似条件下带电粒子对电磁波的散射模型,推导了电磁波经过雷暴云中冰晶粒子区域时产生极化的计算模型,并进行了仿真和分析。结果表明:在传播过程中,电磁波的极化会受到冰晶粒子所带电荷的影响;冰晶粒子所带电荷量越多,对电磁波极化影响越大;冰粒表面电荷分布角越小,对电磁波的极化影响也越严重;电磁波频率和冰晶浓度越高,对电磁波造成的极化作用也越大,影响电磁波的传输质量。因此,在电磁波经过雷暴云时必须考虑带电冰晶粒子对其传播的影响。     

Ice radar investigation at Dome A, East Antarctica: Ice thickness and subglacial topography

Dome A, located in the central East Antarctic ice sheet (EAIS), is the highest summit of the Antarctic ice sheet. From ice-sheet evolution modeling results, Dome A is likely to preserve over one million years of the Earth’s paleo-climatic and -environmental records, and considered an ideal deep ice core drilling site. Ice thickness and subglacial topography are critical factors for ice-sheet models to determine the timescale and location of a deep ice core. During the 21st and 24th Chinese National Antarctic Research Expedition (CHINARE 21, 2004/05; CHINARE 24, 2007/08), ground-based ice radar systems were used to a three-dimensional investigation in the central 30 km×30 km region at Dome A. The successfully obtained high resolution and accuracy data of ice thickness and subglacial topography were then interpolated into the ice thickness distribution and subglacial topography digital elevation model (DEM) with a regular grid resolution of 140.5 m×140.5 m. The results of the ice radar investigation indicate that the average ice thickness in the Dome A central 30 km×30 km region is 2233 m, with a minimal ice thickness of 1618 m and a maximal ice thickness of 3139 m at Kunlun Station. The subglacial topography is relatively sharp, with an elevation range of 949–2445 m. The typical, clear mountain glaciation morphology is likely to reflect the early evolution of the Antarctic ice sheet. Based on the ice thickness distribution and subglacial topography characteristics, the location of Kunlun Station was suggested to carry out the first high-resolution, long time-scale deep ice core drilling. However, the internal structure and basal environments at Kunlun Station still need further research to determine.