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We present a new method to create realistic paint simulation, utilizing the characteristics of paint, such as fluidity, diffusion, and absorption. We treat the painting elements separately as pigment, binder, solvent, and paper. Adopting smoothedparticle hydrodynamics including a consideration of viscoelastic movement, we simulate the fluid motion of the paint and the solvent. To handle the diffusion of the pigment in the solvent, we utilize the mass transfer method. Following Fick's law, the concentration of pigment changes and each pigment particle is diffused to the neighborhood accordingly. As time elapses, the binder and the solvent are absorbed, and for the most part, the pigment remains on the paper. The LucasWashburn equation determines the distance of absorption. The examples show that our approach can effectively generate various types of painting.

The vortical motion of fluid in various scales is one of the most important elements in capturing the vivid realism of turbulent water. However, it is still challenging to resolve mul-ti-level vorticity effectively. This paper presents a novel hybrid method that combines a smoothed particle hydrodynamics (SPH) system with multiple Eulerian grids to reproduce the multi-level vorticity. In our hybrid method, the SPH system is responsible for resolving flow velocity while the multiple grids support the SPH system in efficiently detecting and computing the multi-level vor-ticity field.

We propose a geometric approach to animating thin surface features of smoothed particle hydrodynamics-based water. Explicit interparticle connections are created among smoothed particle hydrodynamics particles to approximate the geometries of thin surfaces while addressing the issue of unresolved surface areas. The deformations measured on the connections actuate the animations of the surfaces by disconnecting the stretched and bent connections. The reconstruction of thin surfaces and the accuracy of the animation are improved by adding auxiliary particles over the connections via Poisson-disk sampling.

BACKGROUND: Wicheon watershed has the largest irrigation area among the mid-watershed of Nakdong river. However, no investigation of irrigation water quality has been conducted on the Wicheon watershed, which evaluates the effects on the soil quality and crop cultivation. Therefore, this study aims to provide various assessments of water quality of Wicheon watershed as the scientific basic data for efficient agricultural activities. METHODS AND RESULTS: Water sampling was performed in five locations of the first tributaries of Wicheon. Wicheon watershed showed clean water quality with very low organic matters and safe water quality from metals at all points of investigation. It was estimated that the natural chemical components of Wicheon watershed were originated from water-rock interaction in Gibbs diagram. All samples were concentrated in the type of Ca-HCO 3-Cl in the Piper diagram. The quality of irrigation water was evaluated with sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), and percent sodium (%Na). The values of these water quality indices were in the range of 0.37-0.67,-2.11-0.24, 41.13-84.52% and 11.28-21.84%, respectively, and were classified as good grades at all sites. CONCLUSION: The water quality of Wicheon watershed was very low in salt, indicating good irrigation water suitable for growing agricultural products. We hope that the results of this study will be used as the basic data for the cultivation of agricultural products and promotion of their excellence.