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Fluid Power Principles
Published in Anton H. Hehn, Fluid Power Troubleshooting, 1995
When a force is applied to a confined liquid, the liquid exhibits the same effect of rigidity as a solid. However, the force is transmitted not only straight through to the other end, but in every direction throughout the confined fluid. The force is transmitted equally forward, backward, and sideways. The pressure of a liquid can be directed around corners. It can be bent back on itself. It can transmit force to any point reached by the confined liquid.
Molecular simulation of liquid crystals
Published in Molecular Physics, 2019
To keep the review within reasonable bounds, it will concentrate on models using freely translating and rotating objects, which attempt to represent the shape and structure of a molecule, or colloidal particle. Unfortunately, there will be no room to discuss interesting recent work based on continuum descriptions [12], lattice spin models [13], or mesoscale methods such as lattice Boltzmann simulations [14] and multi-particle collision dynamics [15]. Simulations of amphiphilic molecules [16] are out of scope, although the growing interest in ionic and polar liquid crystals has led to the inclusion of some examples which are on the border with this field. Again, for reasons of space, the interesting topics of chromonic liquid crystals [17] and polymer liquid crystals [18] cannot be included. While confined liquid crystals are mentioned, simulations of purely two-dimensional systems have had to be omitted.
Anchoring transition of confined prolate hard spherocylinder liquid crystals: hard needle-wall potential
Published in Liquid Crystals, 2018
Mehri Aghaei Semiromi, Abolghasem Avazpour
Surface anchoring first observed by Mauguin which rubbed mica surface with a piece of paper and showed that the liquid crystal molecules aligned near the surface [4]. Following the work of Mauguin, many experimental studies on liquid crystal anchoring have been performed [2]. Due to the importance of confined liquid crystals, a large number of theoretical studies such as density functional theory (DFT) [5–7], Van der Waals type theory [8], and mean field approximation [9,10] have been performed on the surface anchoring. Confined liquid crystals also have been studied by a series of computer simulations [11–17]. There are some methods to constrain the nematic director at an interface that has been briefly listed by Sluckin in Ref. [18]. In adsorption effect, the liquid crystal molecules in the first layer are strongly bounded and oriented in particular directions [18]. Both planar [14,19–21] and homeotropic anchoring [5,22–24] have been achieved with molecular adsorption in confined liquid crystals.
Probing interfacial dynamics of water in confined nanoporous systems by NMRD
Published in Molecular Physics, 2018
As shown in Figure 2, the time dependence of the intermittent dynamics of a confined fluid near a pore interface can be analysed using two density probability distribution (p.d.f.). The first p.d.f [4], ΨA(t) characterises the way according to which an adsorbed molecule is released in the bulk. ΨA(t), is the distribution of adsorption time separating an entrance in the proximal zone and its first desorption to the distal region. The first moment of ΨA(t), τA, is the average time spent in the adsorption region between a first entry and the consecutive first exit. The second important p.d.f, referred to as ΨB(t), is the bridge statistics that provides the time distribution between a desorption event and the next first possible reencounter within the proximal zone. The first moment of ΨB(t) is noted τB. Various analytical expressions of ΨB(t) were discussed in the literature especially for what we call an ‘open surface’ such as flat [3,12], rough [13] or external cylindrical interfaces [14]. In such cases, bridge statistics of a Brownian motion exhibit an algebraic tail at long time, evolving as c/t1+µ with 0<µ<1. On the contrary for nanoporous networks, one generally observes an exponential cut-off, suppressing a large part of the algebraic tail of ΨB(t), at long time. This point was checked recently by extended molecular dynamics simulation of confined liquid water filling either a hydrophilic SiO2 or a hydrophobic carbon nanopore [5].