Numerical investigation on the influence of contact characteristics on nonlinear flow in 3D fracture

Abstract

The objective of this paper is to investigate the effects of contact rate on fluid flow through rock fractures. Different contact rate fracture models are constituted by changing the relative position of the upper and lower fracture surfaces, which is realized with the three-dimensional scanning technology. The results indicate that the generation of contact area and the increase of contact rate will enhance the nonlinearity of fracture fluid flow, and the influence of inertial force in fluid will be more obvious, under which the regime of fracture fluid flow will turn from linear to nonlinear earlier. The entire pressure field and velocity field in fracture are obviously affected by the contact rate. An obvious pressure dividing line appears near the contact area, and the pressure gradient and velocity increase significantly across the dividing lines. The phenomenon of groove flow exists between the contact areas, and eddy is generated on the back flow area of the contact area. The eddy area increases with the Re, the effective flow aperture is further compressed, and the local velocity increases. In the three-dimensional view, it is discovered that the streamline in the double eddy system is distributed in an “8″ shape, and there is flow exchanges between the two eddies.