Viscoelastic-Plastic Constitutive Model For Sea Ice Dynamics Under Meso-Small Scale And Numerical Simulation With SPH Method

The sea ice motion is an important portion of the global water circulate, which has obvious influence on the global climate change and the marine activities in cold regions. The sea ice dynamics mainly includes the sea ice motion, breakup, rafting and ridging under the driving of ocean and atmosphere. The constitutive model, which describes the internal action of ice cover, is the key point to improve the accuracy of sea ice simulation.This paper is supported by the National Science Foundation of China (Grant No. 40206004). The state-of-art of the constitutive model of sea ice dynamics was summarized and analyzed in this paper firstly. Combined with dynamical characteristics and engineering demands of oil/gas exploitation in the Bohai sea ice, and the disadvantages of constitutive models for sea ice dynamics under meso-small scale was discussed in details.The influences on the climate and economy of sea ice were presented in details, and the developing process of constitutive model for sea ice dynamics was reviewed also. The open problems and shortcomings in the constitutive model of sea ice dynamics were pointed out. Based on the discussions above, the main studies of this thesis were introduced considering the sea ice characteristics in the Bohai Sea under meso-small scale.The series of numerical method as Finite Different Method (FDM), Particle-In-Cell (PIC). Smoothed Particle Hydrodynamics (SPH) and Material Point Method (MPM) et al were introduced. Considering characteristic of the Bohai Sea, the SPH basic theory was introduced detailed. Based on the SPH theory, the moment equation and viscoelastic-plastic constitutive model of sea ice dynamics were described.The viscoelastic-plastic constitutive model for sea ice dynamics was established under meso-small scale. In this model, the Kelvin-Vogit viscoelastic model is adopted before ice yielding. And the Drucker-Prager yield criterion and the generalized twin shear stress yield criterion considering the effect of intermediate principal stress was adopted, respectively. In the yielding state, the associated normal flow rule is used. The effect of hydrostatic pressure was also considered in this model. Using the VEP model above, some numerical simulations were carried out to model the sea ice ridging process in an idealized rectangular basin. Moreover, the sea ice numerical simulation of Bohai Sea, and the sea ice parameter evolution process in the JZ20-2 ice field wcre also simulated. The reliability of this viscoelastic-plastic model was validated with these numerical simulation tests. Considering of the influences of sea ice thermodynamic factors on ice conditions, a sea ice thermodynamic-dynamic model was established based on the SPH model for sea ice dynamics. With this present sea ice model, the sea ice of Bohai Sea was simulated in 48 hours. The ice thickness, temperature in vertical direction of sea ice and the other thermodynamic factors were also discussed.The mechanism of cohesion in the generation of ice rubble and ice ridging, the main factors arc demonstrated and analyzed elementarily. Considering three sea ice ridging process. the cohesion is set up as a function of initial ice thickness, total ice thickness, temperature and salinity, respectively. The theoretic expressions of sea ice cohesion were determined and to be introduced into the Mohr-Coulomb yield criterion. The viscoelastic-plastic constitutive model of sea ice dynamics was established considering the cohesion influence here. Meanwhile, the analytical solution was determined under the different conditions. The numerical tests were carried out into sea ice ridging process with this constitutive model. The distributions of sea ice thickness were obtained and the influence of correlative parameters on correlative was discussed.