Numerical Modeling of Micro-Channel Flows by a DPD Method

2003 ◽  
Author(s):  
Justyna Czerwinska ◽  
Nikolaus A. Adams
Keyword(s):  
Molecular Dynamics ◽  
Gas Flow ◽  
Dissipative Particle Dynamics ◽  
Variable Mass ◽  
Coarse Graining ◽  
Voronoi Cell ◽  
Particle Model ◽  
Computational Technique ◽  
Micro Channel ◽  
Micro Fluidics

This paper proposes new computational technique to model micro-flows. The presented below method is based on the meso-scale description of fluid. Dissipative Particle Dynamics (DPD) method is derived from Molecular Dynamics by means of coarse graining procedure. The dissipative particle is defined as a Voronoi cell with variable mass and size; evolves similarly to the Molecular Dynamics particles, except that inter-particle forces have additionally fluctuating, dissipative and stochastic component. This representation leads to the set of equations describing DPD approach. In this paper the outline of the DPD method for application to micro-fluidics flow is presented. DPD method in the form of Soft Fluid Particle model, was mainly applied in material science simulation. This paper presents new approach to model micro-flow by Voronoi Particle DPD method. As a particular example the gas flow in micro-channel flow is computed.

scholarly journals Renormalization group theory of molecular dynamics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daiji Ichishima ◽  
Yuya Matsumura
Keyword(s):  
Molecular Dynamics ◽  
Renormalization Group ◽  
Critical Exponent ◽  
Computational Efficiency ◽  
Large Scale ◽  
Dissipative Particle Dynamics ◽  
Computational Cost ◽  
Coarse Graining ◽  
Spatial Dimension ◽  
Deborah Number

AbstractLarge scale computation by molecular dynamics (MD) method is often challenging or even impractical due to its computational cost, in spite of its wide applications in a variety of fields. Although the recent advancement in parallel computing and introduction of coarse-graining methods have enabled large scale calculations, macroscopic analyses are still not realizable. Here, we present renormalized molecular dynamics (RMD), a renormalization group of MD in thermal equilibrium derived by using the Migdal–Kadanoff approximation. The RMD method improves the computational efficiency drastically while retaining the advantage of MD. The computational efficiency is improved by a factor of $$2^{n(D+1)}$$ 2 n ( D + 1 ) over conventional MD where D is the spatial dimension and n is the number of applied renormalization transforms. We verify RMD by conducting two simulations; melting of an aluminum slab and collision of aluminum spheres. Both problems show that the expectation values of physical quantities are in good agreement after the renormalization, whereas the consumption time is reduced as expected. To observe behavior of RMD near the critical point, the critical exponent of the Lennard-Jones potential is extracted by calculating specific heat on the mesoscale. The critical exponent is obtained as $$\nu =0.63\pm 0.01$$ ν = 0.63 ± 0.01 . In addition, the renormalization group of dissipative particle dynamics (DPD) is derived. Renormalized DPD is equivalent to RMD in isothermal systems under the condition such that Deborah number $$De\ll 1$$ D e ≪ 1 .

Mesoscopic Simulations of Flow in Microchannel and Comparison With Continuum Model

2008 ◽  
Author(s):  
Anurag Kumar ◽  
Yutaka Asako ◽  
Mohammad Faghri
Keyword(s):  
Fundamental Problem ◽  
Molecular Model ◽  
Dissipative Particle Dynamics ◽  
Continuum Theory ◽  
Coarse Graining ◽  
Simulation Method ◽  
Particle Model ◽  
Soft Particle ◽  
Good Agreement ◽  
The Continuum

Dissipative particle dynamics (DPD) is a mesoscopic particle-based simulation method, where each particle represents a group or packet of actual molecules of the flow field. Despite its usefulness, a fundamental problem of the DPD is that there is no straightforward procedure to relate the soft-particle model to a realistic continuum or molecular model. In the present work, we studied the dynamics of a simple fluid flow in a microchannel based on the coarse-graining of the molecules and expressed DPD units in terms of real units. To compare DPD methodology with continuum theory, a relation between the viscosity of the fluid and dissipative coefficient of DPD was established. DPD equations and parameters were expressed in non-dimensional forms and related to the known hydrodynamic parameters such as Reynolds number and Peclet number. Poiseuille flow of water in microchannel of height 35 μm was modeled for different parameters. Coarse-graining for water was ranged from 5×109 to 5×1010 for each DPD particle. Re and Pe of the flow were varied from 0.7 to 60 and 5 to 140, respectively. Simulated results were compared to the continuum results with a good agreement.

scholarly journals Towards bio-inspired artificial muscle: a mechanism based on electro-osmotic flow simulated using dissipative particle dynamics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ramin Zakeri
Keyword(s):  
Zeta Potential ◽  
Electric Field ◽  
Dissipative Particle Dynamics ◽  
Artificial Muscle ◽  
Particle Dynamics ◽  
Polymer Membrane ◽  
Channel Width ◽  
Micro Channel ◽  
Osmotic Flow ◽  
Electro Osmotic Flow

AbstractOne of the unresolved issues in physiology is how exactly myosin moves in a filament as the smallest responsible organ for contracting of a natural muscle. In this research, inspired by nature, a model is presented consisting of DPD (dissipative particle dynamics) particles driven by electro-osmotic flow (EOF) in micro channel that a thin movable impermeable polymer membrane has been attached across channel width, thus momentum of fluid can directly transfer to myosin stem. At the first, by validation of electro-osmotic flow in micro channel in different conditions with accuracy of less than 10 percentage error compared to analytical results, the DPD results have been developed to displacement of an impermeable polymer membrane in EOF. It has been shown that by the presence of electric field of 250 V/m and Zeta potential − 25 mV and the dimensionless ratio of the channel width to the thickness of the electric double layer or kH = 8, about 15% displacement in 8 s time will be obtained compared to channel width. The influential parameters on the displacement of the polymer membrane from DPD particles in EOF such as changes in electric field, ion concentration, zeta potential effect, polymer material and the amount of membrane elasticity have been investigated which in each cases, the radius of gyration and auto correlation velocity of different polymer membrane cases have been compared together. This simulation method in addition of probably helping understand natural myosin displacement mechanism, can be extended to design the contraction of an artificial muscle tissue close to nature.

THE SIMULATION OF POLYSTYRENE/NANOPARTICLES COMPOSITE MICROSPHERES USING DISSIPATIVE PARTICLE DYNAMICS

2013 ◽  
Vol 12 (02) ◽  
pp. 1250111 ◽  
Author(s):  
HAILONG XU ◽  
QIUYU ZHANG ◽  
HEPENG ZHANG ◽  
BAOLIANG ZHANG ◽  
CHANGJIE YIN
Keyword(s):  
Dissipative Particle Dynamics ◽  
Sodium Dodecyl ◽  
Coarse Graining ◽  
Particle Dynamics ◽  
Coarse Grained ◽  
Polystyrene Nanoparticles ◽  
Coarse Grained Model ◽  
Composite Microspheres ◽  
Polystyrene Matrix ◽  
Materials Studio

Dissipative particle dynamics (DPD) was initially used to simulate the polystyrene/nanoparticle composite microspheres (PNCM) in this paper. The coarse graining model of PNCM was established. And the DPD parameterization of the model was represented in detail. The DPD repulsion parameters were calculated from the cohesive energy density which could be calculated by amorphous modules in Materials Studio. The equilibrium configuration of the simulated PNCM shows that the nanoparticles were actually "modified" with oleic acid and the modified nanoparticles were embedded in the bulk of polystyrene. As sodium dodecyl sulfate (SDS) was located in the interface between water and polystyrene, the hydrophilic head of SDS stretched into water while the hydrophobic tailed into polystyrene. All simulated phenomena were consistent with the experimental results in preparation of polystyrene/nanoparticles composite microspheres. The effect of surface modification of nanoparticles on its dispersion in polystyrene matrix was also studied by adjusting the interaction parameters between the OA and NP beads. The final results indicated that the nanoparticles removed from the core of composite microsphere to the surface with increase of a OA-NP . All the simulated results demonstrated that our coarse–grained model was reasonable.

Coarse-Graining of Chain Models in Dissipative Particle Dynamics Simulations†

2011 ◽  
Vol 50 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Justin R. Spaeth ◽  
Todd Dale ◽  
Ioannis G. Kevrekidis ◽  
Athanassios Z. Panagiotopoulos
Keyword(s):  
Dissipative Particle Dynamics ◽  
Coarse Graining ◽  
Particle Dynamics ◽  
Dynamics Simulations

Multiscale Modeling of Flow Induced Thrombogenicity Using Dissipative Particle Dynamics and Molecular Dynamics

2013 ◽  
Author(s):  
Danny Bluestein ◽  
João S. Soares ◽  
Peng Zhang ◽  
Chao Gao ◽  
Seetha Pothapragada ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Blood Flow ◽  
Red Blood Cells ◽  
Platelet Activation ◽  
Blood Cells ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
Coagulation Cascade ◽  
Shear Stresses ◽  
Activated Platelets

The coagulation cascade of blood may be initiated by flow induced platelet activation, which prompts clot formation in prosthetic cardiovascular devices and arterial disease processes. While platelet activation may be induced by biochemical agonists, shear stresses arising from pathological flow patterns enhance the propensity of platelets to activate and initiate the intrinsic pathway of coagulation, leading to thrombosis. Upon activation platelets undergo complex biochemical and morphological changes: organelles are centralized, membrane glycoproteins undergo conformational changes, and adhesive pseudopods are extended. Activated platelets polymerize fibrinogen into a fibrin network that enmeshes red blood cells. Activated platelets also cross-talk and aggregate to form thrombi. Current numerical simulations to model this complex process mostly treat blood as a continuum and solve the Navier-Stokes equations governing blood flow, coupled with diffusion-convection-reaction equations. It requires various complex constitutive relations or simplifying assumptions, and is limited to μm level scales. However, molecular mechanisms governing platelet shape change upon activation and their effect on rheological properties can be in the nm level scales. To address this challenge, a multiscale approach which departs from continuum approaches, may offer an effective means to bridge the gap between macroscopic flow and cellular scales. Molecular dynamics (MD) and dissipative particle dynamics (DPD) methods have been employed in recent years to simulate complex processes at the molecular scales, and various viscous fluids at low-to-high Reynolds numbers at mesoscopic scales. Such particle methods possess important properties at the mesoscopic scale: complex fluids with heterogeneous particles can be modeled, allowing the simulation of processes which are otherwise very difficult to solve by continuum approaches. It is becoming a powerful tool for simulating complex blood flow, red blood cells interactions, and platelet-mediated thrombosis involving platelet activation, aggregation, and adhesion.

Experimental Study on Roughness Effect for Laminar Micro-Channel Gas Flow

2001 ◽  
Author(s):  
Jih-Hsing Tu ◽  
Fangang Tseng ◽  
Ching-Chang Chieng
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Friction Factor ◽  
Gas Flow ◽  
Micro Channel ◽  
Micro Machining ◽  
Roughness Effect ◽  
Relative Roughness ◽  
Smooth Channel ◽  
Micro Channels

Abstract Present study investigates the roughness effect on laminar gas flow for microchannels ranging from 40 to 600 μm with various roughness heights (40–82 nm) by systematical experiments. The micro-channels are manufactured by micro-machining technology and KOH anisotropic etching is employed to achieve various roughness patterns. Experimental results shows that higher product levels of Reynolds number (Reh) and friction factor (f) are obtained for microchannels of larger size and smaller relative roughness and friction factor f approaches to laminar flow theory value f0 for very smooth channel but the ratio of (f/f0) decreases as the surface roughness increases.

scholarly journals Correction: Dissipative particle dynamics and molecular dynamics simulations on mesoscale structure and proton conduction in a SPEEK/PVDF-g-PSSA membrane

RSC Advances ◽  
2017 ◽  
Vol 7 (66) ◽  
pp. 41787-41787
Author(s):  
Yue Ma ◽  
Yuxiang Wang ◽  
Xuejian Deng ◽  
Guanggang Zhou ◽  
Shah Khalid ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
Proton Conduction ◽  
Mesoscale Structure ◽  
Dynamics Simulations

Correction for ‘Dissipative particle dynamics and molecular dynamics simulations on mesoscale structure and proton conduction in a SPEEK/PVDF-g-PSSA membrane’ by Yue Ma et al., RSC Adv., 2017, 7, 39676–39684.

scholarly journals Dissipative particle dynamics and molecular dynamics simulations on mesoscale structure and proton conduction in a SPEEK/PVDF-g-PSSA membrane

RSC Advances ◽  
2017 ◽  
Vol 7 (63) ◽  
pp. 39676-39684 ◽  
Author(s):  
Yue Ma ◽  
Yuxiang Wang ◽  
Xuejian Deng ◽  
Guanggang Zhou ◽  
Sha Khalid ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
Proton Conduction ◽  
Small Particles ◽  
Cluster Network ◽  
Mesoscale Structure ◽  
Dynamics Simulations

The blend morphologies evolve from disordered small particles to a regular PVDF cluster network, which were connected by SPEEK cylindrical channels.

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