title: Virtual-Wall Model for Molecular Dynamics Simulation.
abstract: A large number of molecules are usually required to model atomic walls in molecular dynamics simulations. A virtual-wall model is proposed in this study to describe fluid-wall molecular interactions, for reducing the computational time. The infinite repetition of unit cell structures within the atomic wall causes the periodicity of the force acting on a fluid molecule from the wall molecules. This force is first calculated and then stored in the memory. A fluid molecule appearing in the wall force field is subjected to the force from the wall molecules. The force can then be determined by the position of the molecule relative to the wall. This model avoids excessive calculations of fluid-wall interactions and reduces the computational time drastically. The time reduction is significant for small fluid density and channel height. The virtual-wall model is applied to Poiseuille and Couette flows, and to a flow in a channel with a rough surface. Results of the virtual and atomic wall simulations agree well with each other, thereby indicating the usefulness of the virtual-wall model. The appropriate bin size and cut-off radius in the virtual-wall model are also discussed.
authors.affiliation: Institute of Fluid Measurement and Simulation, Department of Mechanics Engineering, China Jiliang University, Hangzhou 310018, China. qianlj@cjlu.edu.cn.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Qian
authors.affiliation: Institute of Fluid Measurement and Simulation, Department of Mechanics Engineering, China Jiliang University, Hangzhou 310018, China. tuchengxu@cjlu.edu.cn.
authors.forename: Chengxu
authors.initials: C
authors.lastname: Tu
authors.affiliation: Institute of Fluid Measurement and Simulation, Department of Mechanics Engineering, China Jiliang University, Hangzhou 310018, China. dingobao@cjlu.edu.cn.|James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, UK. dingobao@cjlu.edu.cn.
authors.forename: Fubing
authors.initials: F
authors.lastname: Bao
authors.affiliation: James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, UK. yonghao.zhang@strath.ac.uk.
authors.forename: Yonghao
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D056004:Molecular Dynamics Simulation
keywords: fluid-wall interaction; molecular dynamics; nano-scale gas flow; surface roughness; virtual-wall model