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Please use this identifier to cite or link to this item: http://bura.brunel.ac.uk/handle/2438/6818

Title: Boundary condition, an old but not well solved problem, linked from nanometer to macroscale
Authors: Xu, J
Li, Y
3rd Micro and Nano Flows Conference (MNF2011)
Keywords: Boundary condition
Molecular dynamics
Multiscale
Slip length
Publication Date: 2011
Publisher: Brunel University
Citation: 3rd Micro and Nano Flows Conference, Thessaloniki, Greece, 22-24 August 2011
Abstract: A key issue of the flow and heat transfer in channels is to determine the boundary condition, which is affected by various parameters, such as the solid-fluid potential interactions, solid wall roughness, surface wettability etc. We summarize the progress that has been made in recent years. In the first part of this paper, we reviewed the three-atom-model, leading to an important criterion number governing the boundary conditions. The molecular dynamics (MD) simulations verified the effectiveness of the criterion number. The second part of this paper reports the multiscale simulation of the flow field in channels, adjoining the molecular dynamics (MD) simulation and the continuum fluid mechanics. Three types of boundary conditions (slip, non-slip and locking) were identified over the multiscale channel sizes. The slip lengths are found to be mainly dependent on the interfacial parameters with the fixed apparent shear rate. The channel size has little effects on the slip lengths if the size is above a critical value within a couple of tens of molecular diameters. The slip, non-slip and locking interfacial parameters yield positive, zero and negative slip lengths, respectively. The three types of boundary conditions existing in “microscale” still occur in “macroscale”. However, the weak dependence of the slip lengths on the channel size yields decreased slip velocities with increases in channel sizes for all three types of interfacial parameters.
Description: This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.
Sponsorship: This study is supported by the National Natural Science Foundation of China (No. U1034004 and 50825603), and the Basic Research Program (973 program) with the contract number of 2011CB710703.
URI: http://bura.brunel.ac.uk/handle/2438/6818
ISBN: 978-1-902316-98-7
Appears in Collections:Brunel Institute for Bioengineering (BIB)
The Brunel Collection

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