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Showing 3 results for Dissipative Particle Dynamics
Somaye Yaghoubi Koupaye, Ahmad Reza Pishevar, Mohammad Said Saidi, Yaser Afshar, Said Mokhtarian,
Volume 14, Issue 5 (8-2014)
Abstract
Precise ascertainment of the diffusion coefficient as the index of penetration of one species through another is essential for accurate physical modeling. The most precise and careful method for computation of these properties is Molecular Dynamics (MD). Unfortunately these methods have huge computational cost. The aim of this article is to introduce a suitable mesoscopic method and an efficient algorithm for calculating diffusion coefficient using this method. In this study we use Dissipative Particle Dynamics (DPD) for calculating diffusion coefficient of the water and lipid through the biological bilayer membranes. Eventually we validate our results with MD simulation and also experimental results. Then we can conclude about this method that besides being efficient from point of computational cost, the proposed algorithm is an accurate method for calculating diffusion coefficient. Therefore using this method, we are able to study the equilibrium behavior of bilayer membranes like calculating diffusion coefficient which with Molecular Dynamics simulations, it maybe takes more than hundreds of times.
Elnaz Zohravi, Ebrahim Shirani, Ahmad Reza Pishevar,
Volume 17, Issue 10 (1-2018)
Abstract
The radios of particles in Dissipative Particle Dynamics (DPD) method is investigated numerically taking into account size and type of conservative force. In the most of previous studies, the DPD particles have been considered as a point center of repulsion with zero radios and hence sphere size is prescribed by the creation of a structure of frozen DPD particles. Although only in ideal gas state or zero conservative force the DPD point particle is meaningful and with conservative force the DPD particles have an intrinsic size which is assigned by the spherical impenetrable domain occupied by each particle when immersed in a sea of other particles. At first the appropriate method should be define to calculate the size of DPD particle. Different methods including Stokes-Einstein relation, Stokes law and radial distribution function (RDF) are studied and it is concluded that according to limitation of Stokes-Einstein and Stokes relations the RDF is the best method for evaluation of DPD particle size. In the following, the trend of DPD particle size changing and their distribution in the system with linear and exponential conservative force examined. At the end we demonstrate that the employing of exponential conservative forces for the colloid-colloid and colloid-solvent interactions but keep the conventional linear force for the solvent-solvent interactions achieve a well-dispersed suspension with different particle sizes without extra computation
M. Ghafarian Eidgahi Moghadam, M.m. Shahmardan , M. Norouzi,
Volume 19, Issue 4 (4-2019)
Abstract
Magneto-rheological damper is one of the most widely used mechanical equipment, which absorbs mechanical shocks by use of magnetic fluid and electrical coil in its structure. In this paper, for the first time, dissipative particle dynamics as a mesoscopic scale modeling method was used to simulate a magneto-rheological damper and its magnetic fluid. Data from 3 categories including magnetic fluids with brand names 122-EG, 132-DJ, and 140-CG have been used and effect of their physical properties on power of damping force have been investigated. Results of modeling show that by increasing shear rate of fluid, shear stress is first increased and, then, it is applied to a constant value, which results in a greater shear stress by applying a stronger magnetic field. It is also observed that, with increasing both maximum piston velocity and strength of magnetic field, maximum power of damping force increased, which in 140-CG is higher than the other fluids. Results of sensitivity analysis show that weight of magnetic particles and strength of dissipative forces have the greatest effect on damping force, in such a way that by increasing weight of magnetic particles and decreasing the dissipative force of particles, accumulation of magnetic particles decrease, so, increasing quality of damping. It was also found that 122-EG is more suitable than other types of magnetic fluids in forming standard magnetic particle chains, and provides a more favorable viscosity distribution for damping.
