Study On The Application Of Irreversible Thermodynamics In The Problems Of Porous Media Seepage

The irreversibility is the essential characteristic of porous media seepage problems. In allusion to the irreversible behavior of porous media seepage process, the research thought and method of irreversible thermodynamics are attempted to introduce in the research on porous media seepage system, and some positive conclusions have been achieved.Due to the complexity of porous media, the analytical theory about porous media seepage must be based on the method of porous media continuum hypothesis. On the basis of the entropy expression of viscous flow, the entropy expression of porous media seepage under porous media continuum hypothesis is studied and put forward, and their unification is verified in pipe model.Porous media systems usually have complex macroscopical geometric structure. The idea of macroscopical geometric classification of porous media is brought forward in this paper, which enables the simplified analytical method to be established in the system with complex macroscopical geometric structure. In addition, this method also helps to establish corresponding transportation model aiming at specific problems, which has much importance to wider and deeper application of porous media seepage theory.In the paper, the dissipation behavior of porous media seepage process is analyzed, and it is presented that irreversibility is the essential characteristic of porous media seepage process. The minimum energy dissipation principle of seepage problem is put forward and deduced, which is so adaptive and maneuverable that is used as the theoretical basis for the viariational principle of porous media seepage. After the integrated study of various boundary hydraulic conditions and field hydraulic conditions, a new method that the hydraulic conditions of seepage can be classified as three boundary conditions and three field conditions is presented. The variational expressions of various hydraulic conditions in seepage problems are deduced based on minimum energy dissipation principle, and the variational principles of seepage problems are enriched and developed.The application of minimum energy dissipation principle in differentmicroscopical porous media systems is studied, some application problems are listed, and the preferable application value of minimum energy dissipation is laid out. In order to exhibit the application of the method of porous media macroscopical geometric classification and minimum energy dissipation, the combination system between one-dimension pipeline media and three-dimension block media is tried to simulate the destroying and developing process of soil piping erosion.In the study of entropy expression of porous media convection-diffusion process, the reason why minimum entropy production principle is uncomformable is analyzed. In the two-substance attenuate consistency problem, by means of constituting the compulsive convection function of diffusion process, as well as integrating adjoint function, the adjoint variational principle and its finite element method of two-substance attenuate consistency are deduced, and all kinds of dynamic conditions and their variational expressions are discussed. The application value of irreversible thermodynamics in multi-process irreversible transportation problem in the process of porous media seepage is embodied in this paper, and provides new idea and method for the research of kin problems. Based on the method of porous media macroscopic geometric classification and the analytical theory of two-substance attenuate consistency problem, the idea of establishing transportation model of porous media is put forward.