Research And Application On Visualization Method Of Steady Flow Field Based On Triangular Mesh

With the constant development of the research of marine science,people urgently need to display current data graphically.The visualization of flow field can transform the data generated in the process of scientific calculation into images,which is of great significance for revealing the dynamic variation of current and studying the marine environment.Due to the lack of actual observed data of ocean,researchers often use ocean numerical models to explore the mechanism of ocean dynamics.Among them,FVCOM(fine volume coastal ocean model)is a widely used ocean numerical model with unstructured triangulated grid.Owing that the unstructured triangulated grid can fit the land sea boundary better,FVCOM model has been widely used in estuarine and coastal areas.Therefore,this paper studies and applies the visualization method for reanalysis dataset based on FVCOM unstructured triangulated grid:(1)Aiming at the problem that the existing seed placement methods are not suitable for unstructured triangulated grid flow visualization,a seed placement algorithm based on area uniform randomization and critical point detection is proposed.By calculating the area ratio of triangular mesh to achieve the effect of uniform randomization;in order to show the details of the estuarine and coastal areas more easily,the distribution of visualized particles is self-adjusted and optimized with the change of view area.At the same time,combined with the seed point layout in the critical point area,the key flow characteristics in the ocean can be avoided.(2)In order to solve the problem that AMFCA(adaptive step based marine fluid flow line constructing algorithm)is only suitable for regular meshes,different local steps are adopted according to the area of meshes to improve the accuracy of flow visualization.Meanwhile,based on AMFCA algorithm,the angle pixel parameters are added to make the visualization have better display effect in the case of multi-map scale.(3)In order to solve the problem of data redundancy and complexity in the existing point location algorithm which uses unstructured triangulated grid,an improved algorithm based on the edge list is designed and implemented.This method is more suitable for particle tracking in unstructured triangular meshes area with the time complexity in O(1).(4)In order to solve the problem that there are few applications of visualization in fixed field flow field based on unstructured triangulated grid,on the basis of the research of visualization method of triangular mesh fixed field flow field,combined with cesium engine and using Web GL to render the trajectory of particles,the application of visualization of fixed field flow field based on unstructured triangulated grid is realized.At present,the flow field visualization of FVCOM ocean model reanalysis dataset is smooth and accurate,which can be run and displayed on local server.