| 季顺迎,王安良,米丽丽,刘煜,李宝辉.海冰动力过程的改进离散元模型及在渤海的应用[J].海洋学报,2015,37(5):54-67 |
| 海冰动力过程的改进离散元模型及在渤海的应用 |
| Modified discrete element model for sea ice dynamics and its applications in the Bohai Sea |
| 投稿时间：2013-04-28 修订日期：2015-01-11 |
| DOI：10.3969/j.issn.0253-4193.2015.05.006 |
| 中文关键词: 海冰动力学 离散元模型 堆积冰 渤海 |
| 英文关键词:sea ice dynamics discrete element model ice ridge Bohai Sea |
| 基金项目:国家自然科学基金项目(41176012);国家海洋公益性行业科研专项经费项目(201105016, 201205007);高等学校博士学科点专项科研基金项目(20130041110010)。 |
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| 摘要点击次数: 2012 |
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| 中文摘要: |
| 海冰的断裂、重叠和堆积等离散分布特性广泛地存在于极区和副极区的不同海域,并对海冰的生消、运移过程有着重要影响。针对海冰在不同尺度下的离散分布特点,发展海冰动力过程的离散元方法有助于完善海冰数值模式,提高海冰数值模拟的计算精度。为此,本文针对海冰生消运移过程中的非连续分布和形变特性,发展了适用于海冰动力过程的改进离散元模型(MDEM)。不同于传统离散元方法,该模型将海冰离散为具有一定厚度、尺寸和密集度的圆盘单元。海冰单元设为诸多浮冰块的集合体,其在运移和相互接触碰撞过程中,依照质量守恒发生单元尺寸、密集度和厚度的相应变化。基于海冰离散性和流变性的特点,该模型采用黏弹性接触本构模型计算单元间的作用力,并依据Mohr-Coulomb准则计算海冰法向作用下的塑性变形及切向摩擦力。为验证该模型的可靠性,本文对海冰在规则水域内的运移和堆积过程进行了分析,离散元计算结果与解析值相一致;此外,对旋转风场下海冰漂移规律的模拟进一步验证了本文方法的精确性。在此基础上,对渤海辽东湾的海冰动力过程进行了48 h数值分析,计算结果与卫星遥感资料和油气作业区的海冰现场监测数据吻合良好。在下一步工作中将考虑海冰离散元模拟中的热力因素影响,发展具有冻结、断裂效应的海冰离散元模型,更精确地模拟海冰动力-热力耦合作用下的生消和运移过程。 |
| 英文摘要: |
| Breakup,rafting and ridging of ice cover exists widely in the polar and sub-polar regions. These processes affact the growth,vanishing and drifting of sea ice significantly. Considering the discrete distribution of sea ice on various scales,a discrete element model (DEM) should be developed to improve the sea ice numerical model and its computational precission. Thus,a modified discrete element model (MDEM) is established in this study to simulate the sea ice dynamics. Different with the traditional DEM,the ice cover is subdivided into a series of disks with their own characteristics including thickness,velocity,size and concentration,adopting the concept of smoothed particle hydrodynamics (SPH) of sea ice dynamics. Each sea ice element which is an assembly of ice floes changes in its size,concentration and thickness,according with the mass conservation law during drifting and inter-element collisions. According to the non-continuous distribution and rheology characteristics of ice cover,the viscous-elastic constitutive model is adopted. And the Mohr-Coulomb friction law is considered to determine the plastic deformation and tangential friction. To assess the reliability of this MDEM for sea ice dynamics,the drifting and ridging of ice cover in a various-width channel is simulated,and the simulated distribution of ice thickness is validated by the analytical solution. The drifting of sea ice in a rotational wind field is also simulated efficiently with high precision. Moreover,the sea ice dynamics in the Bohai Sea is simulated for 48 h. The simulated results match well with the satellite remote images and field observed data. In the future study,the MDEM will be improved by coupling dynamics and thermodynamics of sea ice. The growth,vanishing and drifting of sea ice will be simulated more accurately by consideringthe refrozen effect and breakage feature of ice cover. |
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