scholarly journals Connection Between Thermodynamics and Dynamics of Simple Fluids in Pores: Impact of Fluid–Fluid Interaction Range and Fluid–Solid Interaction Strength

2017 ◽  
Vol 121 (30) ◽  
pp. 16316-16327 ◽  
Author(s):  
William P. Krekelberg ◽  
Daniel W. Siderius ◽  
Vincent K. Shen ◽  
Thomas M. Truskett ◽  
Jeffrey R. Errington
Langmuir ◽  
2013 ◽  
Vol 29 (47) ◽  
pp. 14527-14535 ◽  
Author(s):  
William P. Krekelberg ◽  
Daniel W. Siderius ◽  
Vincent K. Shen ◽  
Thomas M. Truskett ◽  
Jeffrey R. Errington

2014 ◽  
Vol 574 ◽  
pp. 133-137
Author(s):  
Yan Jia ◽  
Ping Ge Qu

Molecular dynamics method is applied to study the influence of fluid-solid interaction potential on the properties of fluid film in wedge nanochannel. The pressure and density are studied for a variety of potential interaction strength between the liquid and the solid. The impact of potential interaction strength between the liquid and the solid on the pressure is limitation. The density alongydirection is affected by the potential interaction strength. As the potential interaction strength is weak, the density of liquids can be affected easily.


Author(s):  
Junfeng Zhang ◽  
Daniel Y. Kwok

In this paper, we studied liquid-solid slip by employing a mean-field free-energy lattice Boltzmann approach recently proposed [Zhang et al., Phy. Rev. E. 69, 032602, 2004]. With a general bounce-back no-slip boundary condition applied to the interface, liquid slip was observed because of the specific fluid-solid interaction. The slip length is clearly related to the interaction strength: the stronger the interaction, the less hydrophobic the surface and hence results in less slipping. Unlike other lattice Boltzmann models, a contact angle value between 0–180° can be generated here without using a less realistic repulsive fluid-solid interaction. We found that system size does not affect the absolute slip magnitude; however, the ratio of the slip length to system size increases quickly as the system becomes smaller, illustrating that slip becomes important in smaller-scale systems. A small negative slip length can also be produced with a strong fluid-solid attraction. These results are in qualitative agreement with those from experimental and molecular dynamics studies.


Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 356
Author(s):  
Jingbo Shi ◽  
Stavros Avramidis

The nanoscale wood-water interaction strength, accessible sorption sites, and cell wall pore sizes are important factors that drive water sorption and the hysteresis phenomenon in wood. In this work, these factors were quantitatively studied using molecular simulations based on a cell wall pore model, previously developed by the authors. Specifically, the wall-water interaction strength, the sorption sites network including their number, interaction range, strength, and spatial distributions were set at a series of theoretical values as simulation input parameters. The results revealed that most of the investigated parameters significantly affected both sorption isotherms and hysteresis. Water monolayers and clusters were observed on the simulated pore surface when the wood-water interaction and sorption site strength were set at unrealistically high values. Furthermore, multiple linear regression models suggested that wood-water interaction and sorption site parameters were coupled in determining sorption isotherms, but not in determining hysteresis.


2013 ◽  
Vol 20 (2) ◽  
pp. 41-47 ◽  
Author(s):  
Mariusz Żółtowski ◽  
Bogdan Żółtowski ◽  
Leonel Castaneda

Abstract This paper presents a methodology to evaluate the technical state of a Francis turbine by shaft rotor dynamic simulation. There are several rotor dynamic criteria that define the technical state of a turbo-machine. To feed the shaft rotor dynamic model this delivers the required information to accomplish the technical assessment. The numerical rotor dynamic model uses as input, the field forces obtained by the fluid-solid interaction analysis undertaken over the blades of the runner. The rotor dynamic numerical simulations allow to determinate the record-in-time of the displacements of any point along the shaft. This information is relevant for diagnosis tasks, because it is possible to decompose it spectrally and to estimate the severity of the vibrations. Comparing the results of the numerical model against those obtained from machines that operates under normal conditions, it is possible to determinate the technical state of the turbo-machine. This allows studying the stability of the turbine working on several operation ranges. A Francis turbine is a very complex machine that involves many physical phenomena of different nature. In this way, the hydraulic input forces needed by the rotor dynamic model should not be assumed but calculated directly from the fluid interaction over the turbine structure.


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