# Realistic Simulation of Dissolution Process on Rock Surface
## 3 Framework Overview  
The complete dissolution simulation process is based on the movement of water. We regard water as an individual particle and simulate the distribution and trajectory of water according to the rock surface morphology and fracture shape (see Section 4.1). Figure 2 shows the framework of the dissolution simulation process in this paper. In this framework, referring to geological research results [15; 16], we mainly divide the dissolution process into splash dissolution, water flow, dissolution, lateral dissolution under centrifugal force, deposition, and water evaporation. The above processes are explained separately in the following:  
1. Splash dissolution: After dropping onto the rock surface, droplets will play a splash role first, forming a shallow hole-like landscape on the surface; in the splash dissolution process, we mainly calculate the splash dissolution amount based on the maximum material-carrying capacity and splash erosion rate of droplets (see Section 4.2).
2. Water flow: In the process of water flow, droplets will flow along the slope, but if they are in the rock fractures, they will flow along the shape of fracture. If water droplets encounter carbonate content during the flow process, they will undergo a chemical reaction, resulting in dissolution. Rock fractures can affect the flow route of water and thus significantly affect the dissolution effect.
3. Dissolution: In the dissolution process, we will use the carbonate content and water volume to calculate the dissolution rate, and we will then calculate the dissolution amount according to the rate and material volume that water can still carry (see Section 4.3).
4. Lateral dissolution: When the dissolution ditch is obviously curved, the centrifugal force of a droplet will also play a dissolution role on the side wall of a ditch to expand and deepen the fracture. In the horizontal dissolution process under the action of centrifugal force, we calculate the influence area of centrifugal force according to the direction of water velocity, and we calculate the dissolution amount according to water volume, carbonate content, velocity, and centrifugal radius (see Section 4.4).
5. Deposition: In the process of dissolution, the replacement reaction reduces the carbon dioxide content in the droplets. When the content reaches the lower limit, the deposition phenomenon will occur. We will use the deposition rate and the carbonate ion content of water to determine the value of sediment (see Section 4.5).
6. Evaporation: Evaporation will reduce the amount of water. We calculate the amount of water after evaporation based on the evaporation rate and the minimum threshold value (see Section 4.6).  
In the terrain generation module, we use an elevation model as the representation method of terrain information. The elevation data store the information of each point on the terrain surface, which makes it easier to calculate terrain morphology in detail, and it is also suitable for our calculation framework. In addition, the elevation model can be easily converted into a mesh model for rendering. In order to increase a change in surface morphology, we use the method of SimpleX noise function [23] to perturb terrain data, so as to generate random surface morphology.  
In the interactive control interface, users can set parameters related to rainfall, terrain height field, rock solubility, and rock fractures to generate customized dissolution effects. The so-called \"rock solubility\" refers to the proportion of soluble substances (carbonates) in a rock. According to this value, we sample the rock surface randomly to determine the soluble area. Rock fractures will directly affect the trend of water flow, and users can draw it by mouse sketching.  
Figure 2: Dissolution simulation framework.