Abstract: To study the evolution characteristics and influencing factors of vortex structure in rough-walled fracture， COMSOL Multiphysics is used to simulate the flow field under different conditions， and the meso-flow structure is visualized. Based on the response surface methodology (RSM)， a second-order polynomial regression equation is established， and the variance analysis and significance test of the regression equation are carried out， and the effect of multi-factor interaction on vortex structure is discussed. The results show that the evolution process of meso-flow structure in rough-walled fracture includes the generation， development， rupture and stability. The regression model has good significance and adaptability， which can effectively determine the significance of influencing factors. The influencing degree of multi-factor interaction on vortex structure is as follows: average aperture is the largest， followed by velocity， and roughness is the smallest. The results are of great significance to reveal the mesoscopic mechanism of nonlinear seepage in fractures.

Key words: rock fracture； roughness； vortex structure； evolution characteristics； response surface