The molecular dynamic simulation on impact and friction characters of nanofluids with many nanoparticles system
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NANO EXPRESS
Open Access
The molecular dynamic simulation on impact and friction characters of nanofluids with many nanoparticles system Jizu Lv1*, Minli Bai2, Wenzheng Cui2*, Xiaojie Li1
Abstract Impact and friction model of nanofluid for molecular dynamics simulation was built which consists of two Cu plates and Cu-Ar nanofluid. The Cu-Ar nanofluid model consisted of eight spherical copper nanoparticles with each particle diameter of 4 nm and argon atoms as base liquid. The Lennard-Jones potential function was adopted to deal with the interactions between atoms. Thus motion states and interaction of nanoparticles at different time through impact and friction process could be obtained and friction mechanism of nanofluids could be analyzed. In the friction process, nanoparticles showed motions of rotation and translation, but effected by the interactions of nanoparticles, the rotation of nanoparticles was trapped during the compression process. In this process, agglomeration of nanoparticles was very apparent, with the pressure increasing, the phenomenon became more prominent. The reunited nanoparticles would provide supporting efforts for the whole channel, and in the meantime reduced the contact between two friction surfaces, therefore, strengthened lubrication and decreased friction. In the condition of overlarge positive pressure, the nanoparticles would be crashed and formed particles on atomic level and strayed in base liquid. Introduction The concept of nanofluids is first introduced by Choi [1] from Argonne National Laboratory in 1995, which means the stable suspension engineered by suspending nanoparticles of metal, metallic oxide, or non-metallic with average sizes below 100 nm in base fluid. For it has superior heat transfer characteristics and would make remarkable improvement for heat transfer capability of heat exchange equipment, nanofluids has caused widely concerns in recent years. When nanoparticles are added into lubricating oils rather than traditional lubricant, the so-called “nano-lubricant” generates. There have been many investigations on the tribological properties of lubricants with different nanoparticles added [2-17]. The results with many experiments show that nanoparticles
* Correspondence: [email protected]; [email protected] 1 State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116024, China. 2 School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China. Full list of author information is available at the end of the article
added to standard lubricating oils exhibit good frictionreduction and anti-wear properties. The mechanisms of friction-reduction and anti-wear of nanoparticles in lubricant have been many researches [4-17]. Qiu et al. [4] found from their experiment that the tribological mechanism is that a deposit film in the contacting regions was formed, which prevented the direct contact of rubbing surfaces and reduced greatly t
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