A High-Similarity Modeling Method for Low-Porosity Porous Material and Its Application in Bearing Cage Self-Lubrication Simulation

The porous oil-containing cage achieves the storage, spillage, and suction of lubricating oil by its micro-pore structure, thus ensuring the self-lubricating performance of the bearing. Carrying out fast and accurate modeling of the cage microscopic pore structure is the key to the analysis of the self-lubricating mechanism of bearings. In response to the issues where current modeling methods of porous materials have a low similarity of pore distribution, morphology, structure, and size characteristics, and the transition of pore surfaces is sharp, this paper proposed a modeling method of a highly similar micro-pore structure based on the idea of median filtering, the quartet structure generation set (QSGS), and the slice method. By extracting and analyzing the pore characteristics of the porous model and comparing them with the experimental results of CT scanning, the advantages of the modeling method in terms of morphology and pore connectivity were verified. Finally, by carrying out simulation analysis of the centrifugal force of oil splashing and capillary oil absorption on the constructed model by combining the parameters of porous structures such as porosity and tortuosity, the advantages of the modeling method in the construction of the porous model and multi-physical field analysis were further verified.

Influence of Wetting on Viscous Fingering Via 2D Lattice Boltzmann Simulations

We present simulations of two-phase flow using the Rothman and Keller colour gradient Lattice Boltzmann method to study viscous fingering when a “red fluid” invades a porous model initially filled with a “blue” fluid with different viscosity. We conducted eleven suites of 81 numerical experiments totalling 891 simulations, where each suite had a different random realization of the porous model and spanned viscosity ratios in the range $$M\in [0.01,100]$$ M ∈ [ 0.01 , 100 ] and wetting angles in the range $$\theta _w\in [180^\circ ,0^\circ ]$$ θ w ∈ [ 180 ∘ , 0 ∘ ] to allow us to study the effect of these parameters on the fluid-displacement morphology and saturation at breakthrough (sweep). Although sweep often increased with wettability, this was not always so and the sweep phase space landscape, defined as the difference in saturation at a given wetting angle relative to saturation for the non-wetting case, had hills, ridges and valleys. At low viscosity ratios, flow at breakthrough is localized through narrow fingers that span the model. After breakthrough, the flow field continues to evolve and the saturation continues to increase albeit at a reduced rate, and eventually exceeds 90% for both non-wetting and wetting cases. The existence of a complicated sweep phase space at breakthrough, and continued post-breakthrough evolution suggests the hydrodynamics and sweep is a complicated function of wetting angle, viscosity ratio and time, which has major potential implications to Enhanced Oil Recovery by water flooding, and hence, on estimates of global oil reserves. Validation of these results via experiments is required to ensure they translate to field studies.

The Open Constructed Public Sphere: Aeschylus’ The Suppliant Women in a Version by David Greig

This article looks at the ‘public’ ‘place’ of drama in Britain at present by offering an analysis of a contemporary version of an ancient Greek play by Aeschylus, entitled The Suppliant Women, written by David Greig, directed by Ramin Gray, and first performed at the Royal Lyceum Theatre Edinburgh in 2016. Following an agonistic (Chantal Mouffe), rather than a consensual (Jürgen Habermas) model of the public sphere, it argues that under globalisation, three cumulative and interwoven senses of the public sphere, the discursive, the spatial, and the individual and his/her/their relation to a larger form of organisation, despite persisting hegemonic structures that perpetuate their containment, have become undone. This is the kind of unbounded model of public sphere Greig’s version of Aeschylus’ The Suppliant Women seems to suggest by precisely offering undoings of discourses, spaces, and individualisations. In order to frame the first kind of undoing, that is, the unmarking of theatre as contained, the article uses Christopher Balme’s notion of ‘open theatrical public sphere’, and in order to frame the second, that is, the undoing of elements ‘in’ Greig’s version, the article utilises Greig’s concept of ‘constructed space’. The article arrives then at the notion of the open constructed public sphere in relation to The Suppliant Women. By engaging with this porous model of the public sphere, The Suppliant Women enacts a protest against exclusionary, reductive models of exchange and organisation, political engagement, and belonging under globalisation.