Dynamic absorption into simulated porous structures

A computer model, pore-cor11pore-cor is a software program of the Environmental and Fluids Modelling Group, University of Plymouth, PL4 8AA UK. been used to simulate the permeation of fluid into porous structures by applying a wetting algorithm for fluids undergoing both inertial and viscous dynamical absorption. These structures comprise cubic pores connected by cylindrical throats on a three-dimensional 10×10×10 position matrix. Previously, pore-cor has been used to simulate the void structure of porous media by fitting as closely as possible the simulated mercury intrusion curve of the model structure to that of the experimentally determined mercury intrusion curve of the actual sample. This refined model structure was then used to simulate the absorption of a number of different fluids and confirmation with experimental absorption data, adopting the same fluid, provided the necessary confidence in the model. Based on this practical experience, the framework is developed from experimental comparison so that pore-cor can now be applied as a ‘predictor’ tool rather than a simulator of existing experimental results. The structures used here have been generated with the aim of isolating certain parameters so their influence on the absorption behaviour of a fluid can be identified. It is shown how, keeping the porosity constant, structures can be represented in a number of different ways and that these structures will have vastly different absorption behaviour. Reducing the value of the fluid density in the simulation has also been investigated to show where the transition occurs in the absorption behaviour from the linear t-dependent short timescale inertial Bosanquet regime to the √t Lucas–Washburn (LW) viscous regime. Such a system of connecting pores is representative of pigmented paper coating structures and, for example, by changing the particle size distribution of the pigment under suitably modified calendering conditions, pore structures of equal porosity could exist in practice and have drastically different effects on fluid absorption. Implications on, say, the way an ink would set on the coating surface, can have dramatic practical significance. To be able to predict these effects and to design optimal coating structures for the fluids and inks used in a variety of printing, lacquering and glueing processes is seen as a significant advance, obviating the need for expensive matrix-designed production trialling.