| Climate warming is an important distinct trend of global climate. Global warming is amplified in Arctic, it called "Arctic amplification". As the most important feature of polar regions, sea ice has an important influence on atmospheric circulation, ocean circulation and global climate. In recent years, the rapid changes in Arctic sea ice on northern hemisphere weather becomes more and more obvious, so the research on the change of Arctic sea ice is also becoming increasingly important. Among the research methods on polar sea ice. numerical simulation is becoming one of the important means. Ice dynamics describes the interaction between flow and the sea ice. also between atmosphere and the sea ice. when the interaction between flow and sea ice, the drag coefficient is an important factor in determining the flow drag force, and the parameterization on the drag coefficient has been gradually developed.Based on physical model tests, simulate the flow field situation and calculate the drag forces of six kinds ice ridge in five underwater depths and twelve flow velocities by FLUENT software. Firstly, the dynamic characteristics of under-ice flow and stern flow field are analyzed. We find out that the affected area of under-ice flow and stern flow field increases with the increasing slope angle of ice ridge and the underwater depth increase. However, the affected area of under-ice flow and stern flow field decreases with the increasing flow velocity. The vertical section velocity increases with the increasing base angle of ice ridge and the underwater depth. The size of generated vortex behind ice ridge is effected by the slope angle of ice ridge and the underwater depth, while, there is no influence of the flow velocity on them. Compared with the flow field of numerical simulation and physical model test, the difference is that the impact line of stern flow field of numerical simulation is acclivitous. while the impact line of stern flow field of the physical model test is declivitous, except for the above mentioned similar conclusions.Secondly, the characters of drag force is analyzed. We find out that the drag force increases with increasing slope angle of ice ridge and the underwater depth and flow velocity. This conclusion verifies the drag theoretical formula. By compared with the results of numerical simulation and physical model test, we discover that the drag forces fit well except the model with slope angle of 10°. It verifies that the numerical simulation method is feasible and effective. Analysis on the drag coefficient shows that the flow velocity nearly has no effect on drag coefficient, while drag coefficient gradually increase with increasing underwater depth and. And drag coefficient will significantly increase, in addition drag coefficient and base angle of ice ridge are logarithmic relationship.Finally, the impact of the size of the tank on drag coefficient is discussed. We find out that there is no relation between the length of the tank and the drag force. When the depth of the tank reaches 140cm, the drag force of six kinds models will not change with the depth of the tank. In order to apply the results of this study to the real sea ice movement, we eliminate the influence of the size of the tank on the drag force. And we finally get the parametric relationship of ice ridge drag coefficient:Ct=0.3151n(a)-0.616 (R2=0.9989). The result can be used to simulate the real movement of ice. |
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