# Realistic Simulation of Dissolution Process on Rock Surface
## 2 Related Work
### Studies on Dissolution Process in Geology  
In nature, some rock terrains are composed of soluble rocks, and the surface of such rocks will be significantly affected by hydraulic dissolution, forming a unique karst landform. The dissolution process has been deeply studied in geology, mainly including the occurrence conditions, action process, classification, and main factors affecting the dissolution process. After a lot of experiments and research, researchers believe that the main cause of dissolution is water. [PERSON] (2019) and [PERSON] (2019) discussed the development process of karst landforms from the perspective of hydrogeology. They found that after rainfall, the raindrops will splash and erode holes after dropping onto rock surfaces. Subsequently, the water flow will converge to these holes and continue to penetrate and dissolve downward in the process of flow, making the hole expand and deepen. For some rock strata, fractures with different shapes are distributed on them. Under gravity, runoff seeps into the fissures for dissolution, which will gradually expand the fissures and form dissolution channels. The above description roughly reduces the overall process of dissolution. In terms of the classification of karst landforms, their morphology mainly shows the network structures of holes and cracks. Among them, the typical karst surface morphology includes karst pits, karst ditches, and stone forests ([PERSON], 2019). In order to clarify the definition of these three landscapes, researchers have defined their forms. Karst pits refer to depressions with butterfly or inverted cones on a rock surface. After investigation and measurement, [PERSON] concluded that the depth and width of karst pits are about several centimeters, and some large karst pits or karst funnels can be in a steep side wall state ([PERSON], 2019). The dissolution ditch refers to the guilty on the rock surface, which is formed by the dissolution of runoff along the rock surface ([PERSON], 2019). After investigation and measurement, [PERSON] concluded that the length of the dissolution ditch is about several centimeters to ten centimeters, the depth and width are about several centimeters [18]. Some dissolution ditches are developed from rock fractures, so their shape is affected by the fracture trend, and most of them are parallel, dendritic and other cross shapes [20]. Stone forests refer to landscapes composed of a large number of dense columnar or conical rocks, which can also be interpreted as a concave/convex rock landscape composed of a large number of tall stone buds. The side walls of ditches are mostly steep and straight, with a height of about 10 m [18]. Under the continuous action of strong rainfall, the scouring and dissolution of water flow on the rock body will form deep-cut karst pits and ditches. After a long time of development, these karst pits and ditches will come in contact and merge with each other and then form a stone forest landscape. In order to understand the mechanism of the dissolution process more deeply, researchers have studied the important factors that affect the dissolution process, and they are committed to exploring the influence of various factors on the dissolution process. The main factors include rock fracture, precipitation intensity, carbonate ion content in water, etc. In terms of rocks, fractures in rocks can directly determine the trend of dissolution ditches. [PERSON] [21] defined fractures as cracks that occur after a rock is fractured under stress. It is a very common geological phenomenon and can also be understood as the crack of a rock. In terms of water, precipitation intensity and carbonate ion content in water will affect the dissolution process. [PERSON] et al. [22] proposed the hydrochemical runoff method in 1959 and summarized the relationship between hydrochemistry and the dissolution rate. In this relationship, the dissolution rate is determined by the water depth and the calcium carbonate content in water.