The Application Of Inverting Nonlinear Flow Feature Parameters By Double Evaluation Of Particle Swarm Optimization

The parameters of aquifer are the basic physical parameter about quantitative descriptionof aquifer storage and hydraulic conductivity. It is also the essential data about groundwaterresource evaluation. Using the experimental data of pumping, choosing appropriate analyticalsolution for inversion is one of the main ways to determine aquifer parameters.At present, it mainly adopt linear flow model in the groundwater seepage calculation,which is consistent with seepage practical in most cases. However, when the aquifer thicknessis small, medium size is big or water flow rate is large, it is possible appear nonlinear flownear the pumping well.Scholars have made research to nonlinear flow at home and abroad, get the analyticalexpressions of head down and seepage velocity under the condition of constant flow pump,these expressions contain four parameters that express nonlinear feature, it is more complexthan linear flow and it is difficult to application and promotion in practice.In order to solve this problem, this article on the basis of the analytical solution abouttwo-regime about unsteady well flow, apply double evaluation of particle swarm optimizationalgorithm, according to the pumping data, invert nonlinear and aquifer parameters in seepageflow model. Main work is as follows:First, use the method of numerical analysis to make further derivation and simplificationon analytical solution of two-regime about unsteady well flow, get the numerical expression,which can conveniently calculate head down at any time.Second, according to the principle of least squares, construct the target function todetermine of aquifer and nonlinear parameters.Then, the computation procedure of double evaluation of particle swarm optimizationalgorithm is compiled to invert aquifer parameters.At last, through the numerical example it verifies the particle swarm optimizationalgorithm is reliable and feasible.