Several methods for rendering and modeling water have been made and a few of them address the natural phenomenon of water droplets flow. As far as we know; none of those methods have used bump maps in order to simulate the flow of a droplet on structured surfaces. The normals of the bump map; that describes the geometry of the micro structured surface; are used in the flow computation of the droplets. As a result; the water droplets will meander down on the surface as if it has a micro structure. Existing models were not suitable for this purpose. Therefore; a new model is proposed in this paper. The droplet will also leave a trail; which is produced by changing the background texture on the surface. This method will not present a physically correct simulation of water droplets flow on a structured surface. However; it will produce a physically plausible real-time animation.