Bentonite molecular dynamics simulation

Ichikawa Y, Kawamura K, Theramast N, Kitayama K (2(X)4) Secondary and tertial consolidation of bentonite clay consolidation test, molecular dynamics simulation and multiscale homogenization analysis. Mech Mater 36 487-513... 

Abstract We here treat a diffusion problem coupled with water flow in bentonite. The remarkable behavior originates from molecular characteristics of its constituent clay mineral, namely montmorillonite, and we show the behavior based on a unified simulation procedure starting with the molecular dynamic (MD) method and extending the obtained local characteristics to a macroscale behavior by the multiscale homogenization analysis (HA Sanchez-Palencia. 1980). Not only the macroscale effective diffusion property but also the adsorption behavior is well defined based on this method. 

We here showed that for bentonite clay, we can determine the nano-scale material properties such as diffusion coefficient and viscosity by molecular dynamics (MD) simulation and extend the microscale characteristics to the macroscale behavior by the multiscale homogenization analysis (HA) method. A seepage flow and diffusion problem is treated. The micro/macro problem can be simulated well by this procedure if we know the microscale geometrical characteristics. 

In this Section we first show that a local variation of viscosity in the pore water of a saturated smectitic clay such as montmorillonite or beidellite, which is a platelet crystal of about one nanometer (=10 m) thickness, can be calculated by a molecular dynamic (MD) simulation. Then, by applying the HA with the locally distributed viscosity, we can calculate the seepage field of the smectitic clay, which consists of stacks of clay minerals. Consequently, we apply a three-scale analysis of homogenization for a bentonite clay with quartz grains of about 10 [xm (1 fxm = 10 m). 

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