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R S Qin

Publications and source records attributed to R S Qin.

4 recordsLinked to original sources
PubMed2006

Mesoscopic interparticle potentials in the lattice Boltzmann equation for multiphase fluids.

I introduce a method to derive mesoscopic particle interactions by macroscopic thermodynamics, which is suitable for simulation of multiphase fluids by means of the lattice Boltzmann equation. For van der Waals fluids, the interaction possesses a high-density strong repulsive core and a low-density weak attractive tail, which looks like the Lennard-Jones potential with replacement of the distance between particles with mass density. Numerical results on phase separation show a droplet growth scheme rather than spinodal decomposition, and exhibit accurately the equilibrium phase diagram, a convincing interfacial energy property, and irreversible thermodynamics.

Journal Article↗
PubMed2004

Discrete-element method simulations: from micro to macro scales.

Many liquid systems encountered in environmental science are often complex mixtures of many components which place severe demands on traditional computational modelling techniques. A meso scale description is required to account adequately for their flow behaviour on the meso and macro scales. Traditional techniques of computational fluid dynamics and molecular simulation are not well suited to tackling these systems, and researchers are increasingly turning to a range of relatively new computational techniques that offer the prospect of addressing the factors relevant to multicomponent multiphase liquids on length- and time-scales between the molecular level and the macro scale. In this category, we discuss the off-lattice techniques of 'smooth particle hydrodynamics' (SPH) and 'dissipative particle dynamics' (DPD), and the grid-based techniques of 'lattice gas' and 'lattice Boltzmann' (LB). We highlight the main conceptual and technical features underpinning these methods, their strengths and weaknesses, and provide a few examples of the applications of these techniques that illustrate their utility.

Algorithms↗
PubMed2001

[Mechanism study of electrothrombosis by copper needle].

OBJECTIVE: To investigate the mechanism of electrothrombosis by copper needle, in order to supply the referential data for clinical treatment of vessel deformity. METHODS: The mechanism and condition of thrombus formation by copper needle were studied in vivo and in vitro using electrophysics, atom absorption spectrophtometry, histological, and histochemical methods. RESULTS: Great deal of copper ion was dissociated, and agglutination of red blood cells(RBC) in blood could be observed in vitro after the current applied by copper needles. Formation of stable thrombus was related to voltage and time of application of electric current. CONCLUSION: Dissociation of copper ion and agglutination of RBC are the basic principle of electrothrombosis with copper needle. A 4V direct current and 17.5 minutes are the safe and effective conditions for thrombus formation in the blood vessels.

Animals↗