An Experimental Study On Ice Ridge Drag Coefficient In Stratified Fluid

Increase in global temperatures in the Arctic region is amplified, called the Arctic amplification phenomenon. Arctic sea ice in the past few decades has been an unprecedented rapid changes, resulting in the sea ice extent and thickness of the continuous decay, in the middle of this century there may be no ice in the Arctic Ocean in the summer. The rapid changes in the Arctic sea ice have caused more and more significant impact on the northern hemisphere and even the weather and climate in China, and make the opening of the Arctic waterway possible, and become the focus of attention of the governments of all countries. As an important means of sea ice research at present, the numerical simulation of the rapid changes in the Arctic sea ice is still not accurate enough to explain the lack of in-depth understanding of the key physical processes of sea ice. Sea ice drag coefficient is an important parameter in sea ice dynamics model, which is very important to study the dynamic process of ice water. In order to improve the ice water drag coefficient parameterization scheme, taking into account the field observation of dynamic process of the ice water interface were observed the degree of difficulty, this paper aimed at the ice water interface of ice ridge shaped drag, and the drag coefficient to carry out the laboratory physical simulation experiment.First of all, the current ice drag coefficient of parametric study of multi needle for a homogeneous fluid, without considering the stratification of the ocean, and Arctic summer sea ice edge zone of seawater salinity pycnocline due to the influence of sea ice melt generally appear in the shallow position, may affect the movement of ice or ice ridge. Therefore, to improve sea ice in the ice water interface drag coefficient parameterization scheme, on the basis of original laboratory flume were equipment modification, stratified fluid simulation system was established, including saline injection system, drag force measurement system, motion platform system counterweight system. Lay the foundation for the development of stratified fluid experiments.Secondly, as a comparative experiment, to carry out the ice ridge of single-layer fluid drag force measurement, taking into account the 6 kinds of different shapes of ice ridge model in five into the water depth and 12 kinds of flow velocity by the drag force changes. Analysis shows that fluid monolayer ice ridge drag force increased with the increasing of going into the bottom corner of the ice ridge, flow velocity and ice ridge the increase of water depth, ice ridge by drag and speed of the square there is a good linear relationship, this conclusion verified the drag force formula. Analysis of the coefficient of the drag results show that fluid monolayer ridged ice drag coefficient with the flow velocity increases remained basically unchanged, with ice ridge into the water depth increases slowly and increases and smaller increases, with the bottom corner of the ice ridge and significantly larger. Ice ridge corner is the main factor affecting the single-layer fluid drag coefficient of ice ridge.Finally, experimental group and single fluid were consistent in the shape of ice ridge double fluid drag experiment. The results showed that the fluid bilayers of ice ridge drag in drag with the single-layer fluid changes has the obvious difference, when the Froude number is 1-2 interval, fluid bilayers of ice ridge drag show increased first and then decreased trend. When the Froude number greater than 2, the fluid bilayers of ice ridge drag and fluid monolayer in the corresponding value is basically the same, this is mainly due to the influence of interfacial waves caused by. However, the drag coefficient is different than that of single layer fluid. In addition to the influence of the inclination angle of the ice ridge, the influence of the Flood number on the drag coefficient is also obvious. In the Froude number is small (<0.7), drag coefficient with Froude number increases rapidly decay, and ice ridge angle independent; and in the Froude number is large (>0.7), the drag coefficient increases with the increase of ice ridge point of view, has nothing to do with the Froude number. Therefore, the parameters of the drag coefficient of the double layer fluid are obtained by using the piecewise fitting method.