Momentum conserving Brownian dynamics propagator for complex soft matter fluids

Padding, JT Johan; Briels, Willem J.

doi:10.1063/1.4904315

Cited by 4 publications

(11 citation statements)

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“…However, the flow field for soft matter fluids flowing through complex geometries is typically quite complex and is not known a priori. To calculate the background flow field based on the motion of the coarse grain coordinates, we use the momentum conserving Galilean invariant two-way coupling scheme proposed by Padding and Briels 26 with our own modifications. This algorithm couples the motion of the coarse-grain coordinates and the background flow field with each other.…”

Section: B Update Of Velocitiesmentioning

confidence: 99%

“…where the sum in the numerator includes the self term j = i. We must point out that we have changed the definition of ρ i from the original definition proposed in the algorithm by Padding and Briels 26 in order to ensure proper normalization 44 so that for a homogeneous solution, we have ρ = m ρ # , where ρ # is the number density of the particles. Putting together Equations (3)-(6) and including a random term as per the fluctuation dissipation theorem, we arrive at the following equation that we have used in our simulations for the update of the velocities:…”

Section: B Update Of Velocitiesmentioning

confidence: 99%

“…For a detailed derivation starting with the Chapman-Kolmogorov equations leading to a Fokker-Planck equation for the evolution of the probability distribution, we refer to the appendix of the paper by Padding and Briels. 26 Accordingly, we have…”

Section: B Update Of Velocitiesmentioning

confidence: 99%

“…[21][22][23][24][25] A more general momentum-conserving algorithm for modeling self-developing flows of complex fluids in any flow situation has been developed recently. 26 Using this algorithm, friction is applied to the relative motion of the coarse-grained particles with respect to the background fluid. A separate set of variables is used for describing the background fluid velocities, which are updated based on a discretization of the Navier-Stokes equation at the positions of the coarse-grain coordinates, in a way similar to Smoothed Particle Hydrodynamics (SPH).…”

Section: Introductionmentioning

confidence: 99%

“…Although initially developed independently by Padding and Briels, 26 the momentum conserving algorithm bears similarity to an existing modeling technique called Smoothed Dissipative Particle Dynamics (SDPD), 32 which also incorporates thermal fluctuations in the standard SPH approach. SDPD has been shown to obey proper scaling with varying resolution for Brownian motion of a colloidal particle as well as a polymer molecule in suspension.…”

Section: Introductionmentioning

confidence: 99%

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Coarse-grained simulations for flow of complex soft matter fluids in the bulk and in the presence of solid interfaces

Ahuja

Gucht

Briels

2016

The Journal of Chemical Physics

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We present a coarse-grained particle-based simulation technique for modeling flow of complex soft matter fluids such as polymer solutions in the presence of solid interfaces. In our coarse-grained description of the system, we track the motion of polymer molecules using their centers-of-mass as our coarse-grain co-ordinates and also keep track of another set of variables that describe the background flow field. The coarse-grain motion is thus influenced not only by the interactions based on appropriate potentials used to model the particular polymer system of interest and the random kicks associated with thermal fluctuations, but also by the motion of the background fluid. In order to couple the motion of the coarse-grain co-ordinates with the background fluid motion, we use a Galilean invariant, first order Brownian dynamics algorithm developed by Padding and Briels [J. Chem. Phys. 141, 244108 (2014)], which on the one hand draws inspiration from smoothed particle hydrodynamics in a way that the motion of the background fluid is efficiently calculated based on a discretization of the Navier-Stokes equation at the positions of the coarse-grain coordinates where it is actually needed, but also differs from it because of the inclusion of thermal fluctuations by having momentum-conserving pairwise stochastic updates. In this paper, we make a few modifications to this algorithm and introduce a new parameter, viz., a friction coefficient associated with the background fluid, and analyze the relationship of the model parameters with the dynamic properties of the system. We also test this algorithm for flow in the presence of solid interfaces to show that appropriate boundary conditions can be imposed at solid-fluid interfaces by using artificial particles embedded in the solid walls which offer friction to the real fluid particles in the vicinity of the wall. We have tested our method using a model system of a star polymer solution at the overlap concentration.

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Section: B Update Of Velocitiesmentioning

confidence: 99%

Section: B Update Of Velocitiesmentioning

confidence: 99%

Section: B Update Of Velocitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Coarse-grained simulations for flow of complex soft matter fluids in the bulk and in the presence of solid interfaces

Ahuja

Gucht

Briels

2016

The Journal of Chemical Physics

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A mesoscale model for the micromechanical study of gels

Wagner

Dai

et al. 2022

Journal of the Mechanics and Physics of Solids

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Hydrodynamically Coupled Brownian Dynamics: A coarse-grain particle-based Brownian dynamics technique with hydrodynamic interactions for modeling self-developing flow of polymer solutions

Ahuja

Gucht

Briels

2018

The Journal of Chemical Physics

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We present a novel coarse-grain particle-based simulation technique for modeling self-developing flow of dilute and semi-dilute polymer solutions. The central idea in this paper is the two-way coupling between a mesoscopic polymer model and a phenomenological fluid model. As our polymer model, we choose Responsive Particle Dynamics (RaPiD), a Brownian dynamics method, which formulates the so-called "conservative" and "transient" pair-potentials through which the polymers interact besides experiencing random forces in accordance with the fluctuation dissipation theorem. In addition to these interactions, our polymer blobs are also influenced by the background solvent velocity field, which we calculate by solving the Navier-Stokes equation discretized on a moving grid of fluid blobs using the Smoothed Particle Hydrodynamics (SPH) technique. While the polymers experience this frictional force opposing their motion relative to the background flow field, our fluid blobs also in turn are influenced by the motion of the polymers through an interaction term. This makes our technique a two-way coupling algorithm. We have constructed this interaction term in such a way that momentum is conserved locally, thereby preserving long range hydrodynamics. Furthermore, we have derived pairwise fluctuation terms for the velocities of the fluid blobs using the Fokker-Planck equation, which have been alternatively derived using the General Equation for the Non-Equilibrium Reversible-Irreversible Coupling (GENERIC) approach in Smoothed Dissipative Particle Dynamics (SDPD) literature. These velocity fluctuations for the fluid may be incorporated into the velocity updates for our fluid blobs to obtain a thermodynamically consistent distribution of velocities. In cases where these fluctuations are insignificant, however, these additional terms may well be dropped out as they are in a standard SPH simulation. We have applied our technique to study the rheology of two different concentrations of our model linear polymer solutions. The results show that the polymers and the fluid are coupled very well with each other, showing no lag between their velocities. Furthermore, our results show non-Newtonian shear thinning and the characteristic flattening of the Poiseuille flow profile typically observed for polymer solutions.

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Momentum conserving Brownian dynamics propagator for complex soft matter fluids

Cited by 4 publications

References 32 publications

Coarse-grained simulations for flow of complex soft matter fluids in the bulk and in the presence of solid interfaces

Coarse-grained simulations for flow of complex soft matter fluids in the bulk and in the presence of solid interfaces

A mesoscale model for the micromechanical study of gels

Hydrodynamically Coupled Brownian Dynamics: A coarse-grain particle-based Brownian dynamics technique with hydrodynamic interactions for modeling self-developing flow of polymer solutions

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