Application of lattice Boltzmann method in macropore flows in unsaturated zone soil of slopes

The establishment of macropore structure and infiltration simulation is primarily used to explain the mechanism and dynamic change of macropore flows. The macropore domain of unsaturated zone soil of slopes by means of CT scan is acquired. Moreover, based on the lattice Boltzmann method regardless of the external forces, qualitative and quantitative researches on two-dimensional macropore flow seepage process are achieved after the discrete-velocity model, equilibrium distribution function and evolution equation of distribution function are established with boundary conditions and calculation assumptions according to dye tracer experiments. The results show that: (1) This computing method can clearly and quantitatively describe the wetting front propulsion of macropore flows and prove that the macropore effect is obvious, but the effect decreases when the seepage flow velocity gradually tends to be stable. (2) The fluid velocity is faster in better connectivity and larger macropore size area, and the velocity decreases gradually from the center to both sides of macropore which means it is the fastest in the center. (3) The quantity and velocity of fluid flows at the lower depth is under the control of the macropore size at the above depth. The application of the lattice Boltzmann method can offer helps for macropore flows, especially three-dimensional seepage study.