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• An efficient and reliable three-dimensional (3D) ghost cell method is presented for complex rigid and flexible boundary flows. • An improved implicit interface representation method is developed to track the arbitrary complex interfaces. • A GPU-CUDA parallel framework is developed to greatly accelerate the present solver. • The present solver can achieve hundreds of acceleration ratio for 2D grids and thousands of acceleration ratio for 3D grids. • Uniform flows around an 3D body with arbitrary geometries are simulated, and salient 3D wake structures are captured. This paper presents an efficient and reliable three-dimensional (3D) ghost cell method for complex rigid or flexible boundary flows. An improved implicit interface representation method is developed to treat the arbitrary complex interfaces including the thin or sharp boundaries. This method is robust and avoids the solving of a large dense matrix, and thus the computational efficiency is greatly enhanced. The ghost cell method with a unified eight-node interpolation scheme is adopted to enforce the no-slip boundary conditions on complex boundaries. To perform 3D high-resolution simulation on a desktop computer, a GPU parallel framework in CUDA environment is developed to significantly accelerate the computational efficiency of the present solver. The horizontal oscillations of a two-dimensional (2D) cylinder and a 3D sphere in the rest fluid are simulated to validate the accuracy and computational performance of the present model. Spatial accuracy of near second-order on the boundary treatment and good grid convergence are confirmed. Also, the present solver can achieve hundreds of acceleration ratios for 2D grids and thousands of acceleration ratios for 3D grids. Then, uniform flows around a 3D arbitrary rigid or flexible object such as a stationary cylindrical cylinder, a stationary square cylinder, an oscillating airfoil, and a swimming carangiform are simulated. The accuracy and capability of the present model for 3D complex geometries with large-amplitude movement or deformation is satisfactorily validated. Moreover, typical 3D wake structures are well captured. [ABSTRACT FROM AUTHOR]

The Cluster-Cluster Aggregation model (CCA) was often used to simulate the aggregation of colloids, in which the rapid and slow aggregation processes of colloids can be well characterized. In practical system, the movement of particles or clusters occurs in parallel. In the CCA model, in order to facilitate computer simulation, the movement of particles or clusters is processed serially by the method of Metropolis sampling. That is, randomly selecting one particle or cluster to move randomly, colliding with other cluster in the movement, and aggregating according to certain conditions, such aggregation would usually occur between a moving cluster and a static cluster, and this process is essentially a dimerization process. Based on this idea, this study proposes a cluster dichotomy model, in which the dispersion process can be regarded as the inverse process of cluster aggregation, that is, the randomly selected cluster always breaks up into two small clusters. This kind of dispersion is called dichotomy. Based on this model, the rapid and slow dispersion processes of colloidal clusters can be simulated by setting the relevant parameters. The dichotomy model proposed in this paper can be used to study colloidal stability by coupling with the traditional CCA model. [ABSTRACT FROM AUTHOR]