Study And Application In Body-Fitted Coordinates Transformation In The River Ice Simulation

Grids-generation is an important pre-treatment process for the establishment of current numerical models, and is one of the key factors for the CFD calculations. Body-fitted coordinates transformation technology can rapidly generate high-quality grids, which is applied to simulate the river ice. This study has important practical significance for the river ice simulation .This paper analyzes and reviews the advantages and the disadvantages of some common grids-generation technology, and on this basis, generates a new body-fitted grids system by solving elliptic partial differential equations. The paper describes in detail the coordinate transformation and inverse transformation of the two-dimensional elliptic partial differential equations grids-generation method, and uses several common elliptic partial differential equations grids-generation methods for laboratory's curved slots, we obtain two more excellent methods by comparing their result, and the grids are generated for the Hequ section of the Yellow River. The paper also establishes aξ-η-ζcoordinates system and aξ-η-σcoordinates system for the three-dimensional water body. Against the ice condition in natural river is very complex, the body-fitted coordinates transformation is used in the horizontal direction, and theσ- coordinates transformation method is used in vertical direction to generate three-dimensional body-fitted grids. This method is used to generate three-dimensional grids for the laboratory's curved slots and the natural river.Meanwhile, according to the sediment transport theory, the paper also introduces a numerical model for ice jam in theξ-η-σcoordinates system. It is a significant attempt to set up this numerical model.