The nonlinear characteristics of soft gels and hydrated connective tissues in ultrafiltration

Modeling of centrifugal filtration in unsaturated deformable porous media

Porous Elasticity: Lectures on the elasticity of porous materials as an application of the theory of mixtures

A theory for flow in a saturated compressible porous medium is developed to simulate the solid‐liquid separation operations known as expression in practice. A mathematical model that consists of the mass‐conservation equation, quasistate equilibrium equation, stress‐strain relation for an elastic matrix, and a variable total stress expression was employed to obtain numerical solutions for pore pressure and compaction variations due to time‐dependent and constant displacement conditions at the upper boundary of saturated porous columns. Results were obtained for five problems of practical importance. Cases studied include the compression of a porous column with a specified time‐dependent displacement of the upper boundary, compression with instantaneous displacement of the pervious upper boundary of a saturated porous column, compression with time‐dependent displacement at the impervious upper boundary, compaction with an upper boundary moving at a constant velocity, and dynamic compression of a saturated ...

Dynamic Compaction of Saturated Porous Columns

Dewaterability of a compressible suspension can be characterized by two fundamental properties of viscoelastic networks: permeability and bulk modulus of elasticity. Time required for dewatering can be obtained from the former, while the latter can furnish the data required for predict­ ing ultimate compaction. A method has been derived and an apparatus constructed for measurement of these two proper­ ties in a centrifugal field. The method was applied to a variety of drilling fluids and mineral suspensions. A floor-mounted laboratory centrifuge was used in this inves­ tigation. The methods developed have merit for evaluating pre-treatments prior to centrifugal dewatering. A method for quantifying the density distribution from top to bottom of a sedimented cake less than 2 cm in height is reported. In one experiment, this density variation was less than 13%. The feasibility of replacing chemical pre-treatments by applying an alternating current electric field (electrocoag­ ulation) was investigated. Several fluids were electrically treated before centrifuging. Upon centrifuging, only cer­ tain suspensions exhibited a cake while others did not. In those instances where a cake could be collected, its mois­ ture content was measured. In the most effective electrical treatment, a salt/polymer drilling f].uid containing 6% by

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Mechanism and Enhancement of Phase Segregation in Drilling Fluids.

The dynamic compression of a fluid-filled isotropic Hookean elasto-porous medium with non-constant permeability is considered. The governing non-linear partial differential equations for two simple models are set up with the aid of an appropriate approximation and solved numerically for the medium displacements and fluid pressure. The results are compared with a series solution for the case of constant permeability. They indicate that the neglect of variable permeability could result in errors of order one hundred per cent.

B.W. Roberts

Papers

Compression of an elastoporous medium