Comparing theory and simulation for thermo-osmosis

Proesmans, Karel; Frenkel, Daan

doi:10.1063/1.5123164

Cited by 15 publications

(8 citation statements)

References 17 publications

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“…16,17 In fact, there is a debate between two approaches for describing the underlying mechanism for thermo-osmosis, namely the interfacial approach and the energetic approach. 18 Further understanding of thermo-osmosis at the nanoscale is of particular interest because the very limited studies of thermo-osmosis at solid-fluid interfaces [19][20][21][22][23] do not allow for linking the two approaches and for a complete understanding of the underlying mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Thermo-osmosis in hydrophilic nanochannels: mechanism and size effect

2021

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Section: Introductionmentioning

confidence: 99%

Thermo-osmosis in hydrophilic nanochannels: mechanism and size effect

2021

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“…[22,27,[37][38][39] focused on the realization of self-phoretic microswimmers and the study of their dynamical properties utilizing MPC and/or MD simulation methods. Moreover, molecular simulations were used to quantify thermo-osmotic forces and the associated thermo-osmotic slip [40][41][42], also employing MPC and MD methods. Thermal nonequilibrium transport in colloids and the role of hydrodynamic slip were theoretically studied in [43,44], and a unified description of colloidal thermophoresis was suggested in [45] using a nonequilibrium-theromodynamics approach.…”

Section: Atomistic Model Of a Hot Janus Swimmermentioning

confidence: 99%

Coarse Graining Nonisothermal Microswimmer Suspensions

Auschra

Chakraborty²,

Falasco³

et al. 2021

Front. Phys.

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We investigate coarse-grained models of suspended self-thermophoretic microswimmers. Upon heating, the Janus spheres, with hemispheres made of different materials, induce a heterogeneous local solvent temperature that causes the self-phoretic particle propulsion. Starting from molecular dynamics simulations that schematically resolve the molecular composition of the solvent and the microswimmer, we verify the coarse-grained description of the fluid in terms of a local molecular temperature field, and its role for the particle’s thermophoretic self-propulsion and hot Brownian motion. The latter is governed by effective nonequilibrium temperatures, which are measured from simulations by confining the particle position and orientation. They are theoretically shown to remain relevant for any further spatial coarse-graining towards a hydrodynamic description of the entire suspension as a homogeneous complex fluid.

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“…The benefit of the equilibrium approach to compute all the responses should in principle be even larger if one also considers thermal gradient (for instance, following strategies of Ref. [55]) in addition to the ones discussed above, even though dealing with such perturbations in molecular simulations can be challenging.…”

Section: Mobility Matrixmentioning

confidence: 99%

Sampling mobility profiles of confined fluids with equilibrium molecular dynamics simulations

Mangaud,

Rotenberg

2020

Preprint

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We show how to evaluate mobility profiles, characterizing the transport of confined fluids under a perturbation, from equilibrium molecular simulations. The correlation functions derived with the Green-Kubo formalism are difficult to sample accurately and we consider two complementary strategies: improving the spatial sampling thanks to a new estimator of the local fluxes involving the forces acting on the particles in addition to their positions and velocities, and improving temporal sampling thanks to the Einstein-Helfand approach instead of the Green-Kubo one. We illustrate this method on the case of a binary mixture confined between parallel walls, under a pressure or chemical potential gradient. All equilibrium methods are compared to standard non-equilibrium molecular dynamics (NEMD) and provide the correct mobility profiles. We recover quantitatively fluid viscosity and diffusio-osmotic mobility in the bulk part of the pore. Interestingly, the matrix of mobility profiles for local fluxes is not symmetric, unlike the Onsager matrix for the total fluxes. Even the most computationally efficient equilibrium method (Einstein-Helfand combined with the force-based estimator) remains less efficient than NEMD to determine a specific mobility profile. However, the equilibrium approach provides all responses to all perturbations simultaneously, whereas NEMD requires the simulation of several types of perturbations to determine the various responses, each with different magnitudes to check the validity of the linear regime. While NEMD seems more competitive for the present example, the balance should be different for more complex systems, in particular for electrolyte solutions for the responses to pressure, salt concentration and electric potential gradients.

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Comparing theory and simulation for thermo-osmosis

Cited by 15 publications

References 17 publications

Thermo-osmosis in hydrophilic nanochannels: mechanism and size effect

Thermo-osmosis in hydrophilic nanochannels: mechanism and size effect

Coarse Graining Nonisothermal Microswimmer Suspensions

Sampling mobility profiles of confined fluids with equilibrium molecular dynamics simulations

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