The Theory Of Lattice Boltzmann Method And The Application Of To Debris Flow

Debris flow is unexpected natural phenomenon which is commonly found in a mountainous area, whose movement process is non-linear. As a new numerical method of solving the fluid mechanics problems from the field of micro-dynamics, the lattice method may become a new method successfully simulated the nonlinear characteristic of debris flow.In this paper, based on the nonlinear characteristic of debris flow and the experimental results of debris flow ingoing the primary river, carried on some reformation to some the Boltzmann model's factors for example the equilibrium distribution function, the non-equilibrium distribution function etc, several characteristics lattice Boltzmann models were set up successfully simulated debris flow's one-dimensional movement, two-dimensional deposition and debris flow ingoing the primary river.The main work and conclusions were as follows:1,In view of non-linear characteristics of debris flow and debris flow into the main river of complexity, the conclusions can be drew from the theory of lattice Boltzmann method: the lattice gas method is not suitable for debris flow ; the Lattice BGK method for debris flow and debris flow ingoing the primary river is a feasibility study; Lattice Boltzmann method with enhanced collisions for debris flow and debris flow ingoing the primary river need for some transformations and innovations.2,Through solving the Burgers equation, solving one dimension partial-differential equations of the water hammer phenomenon, and simulating the fluid flow in the primary river, the lattice Boltzmann method's application to the Newton fluid flow were studied. From the establishment of the above three lattice Boltzmann models the conclusions can be drew: It is the core of the problem for establishing lattice Boltzmann models of debris flow, how to construct the equilibrium distribution function reflected the characteristics of the nonlinear movement.3,Aimed at debris flow's one-dimensional movement and two-dimensional deposition, two lattice Boltzmann models were established : (1) A Boltzmann models was established whose equilibrium distribution function is a nonlinear function of depth and velocity of debris flow. Under the lattice Boltzmann model, one-dimension movement of debris flow was simulated, and the spatial and temporal variations of depth and velocity were obtained. (2) A Boltzmann model was established whose non-equilibrium distribution function is a linear function of depth and velocity gradient of debris flow. Under the lattice Boltzmann model, the deposition of debris flow was simulated, and the layered configuration of deposit sector of the debris flow was obtained.4,Aimed at the confluence between debris flow and the primary river, the group experiments were conducted. Based on analyzing the experimental phenomena, some conclusions can be seen: (1) some factors for example the ratio of the primary river flux to the debris flow flux, the velocity of the primary river, the ingoing angle etc affect the mechanism of confluence;(2) the mechanism of confluence at ingoing angle 45°is different from the mechanism of the debris flow ingoing the primary river at ingoing angle 90°in essence ;(3) the mechanism of confluence at ingoing angle 30°is similar to the mechanism of the debris flow ingoing the primary river at ingoing angle 60°;(4) the primary river not only has an impact on the debris flow velocity, but on damage configuration of debris flow .there are a lot of difficulty and complexity in dealing with the infection of the primary river.5,Based on the differences of he vertical direction of the primary river velocity between the parallel direction of the primary river velocity ,and different approach of dealing with the infection of the primary river, some lattice Boltzmann model were set up: (1) A Boltzmann models was established whose equilibrium distribution function is a nonlinear function of density ,velocity and momentum gradient of debris flow. Under the lattice Boltzmann model, the debris flow ingoing primary river at ingoing angle 90°is simulated, the result accord with basically the result of experiment which provides a new method for studying movement mechanisms of the confluence between debris flow and the main river. (2) The combined lattice Boltzmann model is set up, which succeed in simulating the debris flow ingoing primary river at ingoing angle 45°, providing a new means for analyzing reciprocity mechanisms of the confluence between debris flow and the main river at different ingoing angle.(3) Use of the rotation of space, the mapping lattice Boltzmann model is set up. Which succeed in simulating the debris flow ingoing primary river at 60°and 30°, which make quantity surveyors realize the different reciprocity mechanisms at different ingoing angle. (4)On account of the fluid flow in the primary river affect the velocity and configuration of the debris flow after confluence, the double equilibrium distributing lattice Boltzmann model are established, which succeed in depicting different infection of the fluid flow on debris flow in differ time and differ space.