In a system containing nanoporous materials and liquids, the well-known thermo-capillary effect can be amplified by the ultralarge specific surface area of the nanopores. With appropriate temperature change, the relative wetting-dewetting transition can cause the liquid to flow in or out of the nanopores, and part of the thermal energy is converted to significant mechanical output. A conceptual design of such a thermal actuation/energy conversion/storage system is investigated in this paper, whose working mechanism, i.e. the thermally dependent infiltration behaviors of liquids into nanopores, is analyzed using molecular dynamics simulations. The fundamental molecular characteristics, including the density profile, contact angle, and surface tension of the confined liquid molecules, are examined in considerable detail. The influences of pore size, solid phase and liquid species are elucidated, which couple with the thermal effect. The energy density, power density, and efficiency of the thermal actuation system are evaluated. An infiltration experiment on a zeolite/water system is performed to qualitatively validate these findings.

Electrolyte transport in nanochannels plays an important role in a number of emerging areas. Using non-equilibrium molecular dynamics (NEMD) simulations, the fundamental transport behavior of an electrolyte/water solution in a confined model nanoenvironment is systematically investigated by varying the nanochannel dimension, solid phase, electrolyte phase, ion concentration and transport rate. It is found that the shear resistance encountered by the nanofluid strongly depends on these material/system parameters; furthermore, several effects are coupled. The mechanisms of the nanofluidic transport characteristics are explained by considering the unique molecular/ion structure formed inside the nanochannel. The lower shear resistance observed in some of the systems studies could be beneficial for nanoconductors, while the higher shear resistance (or higher effective viscosity) observed in other systems might enhance the performance of energy dissipation devices.

In the general mixed finite element analysis for the porous media, a fluid is assumed to be nearly incompressible; however, the solid may undergo a range of deformations from relatively large to small. If both constituent are assumed to be nearly incompressible and impermeable, the finite element analysis is very complex because of element locking. In order to overcome this difficulty, stable procedures using equal order elements have been introduced with stability analyses. However, these methods have a drawback that critical time steps in the stability analysis have to be determined by modal analysis. In this paper, a new coupled analysis based on a stable algorithm is introduced to remedy the drawback. First, governing equations for saturated porous media in frame of Biot's theory are derived on macroscopic sense, and that are represented into approximation forms which is divided into solid and fluid phase for finite element procedure. Moreover, a new coupled analysis based on a stable algorithm is introduced. In this procedure, the multi time step, the remeshing step and the sub iteration step are proposed for a stable analysis. These steps make it possible to simply solve numerical instabilities such as convergence and compatibility problems.

The proposed algorithm in Part1 which is proposed in order to overcome numerical difficulties on nearly incompressible and impermeable conditions for saturated porous media is verified for accuracy and stability by analytical solutions, other methods as well as using available models in the ABAQUS software. We could be obtained good results for state variables from comparing, and the method was reasonably and stably performed for all conditions like compressible, incompressible, permeable or nearly impermeable.

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