A new grid system for dynamic fluid animation that controls the number of particles adaptively according to the viewing distance is proposed in this work. The proposed scalable grid system is developed in association with the semi-Lagrangian method to demonstrate the dynamic fluid behavior solved from the system of Navier-Stokes equations. It contains actual particles and virtual particles. To save computations, only actual particles are used to render images viewed from a standard viewpoint. When we zoom in, virtual particles are added to maintain the resolution of the fluid simulation and provide higher quality rendering. We implement a scalable computing procedure for the diffusion step in fluid simulation. The proposed scalable grid system can be incorporated into any semi-Lagrangian method that uses grid or voxel primitives.