Nanoflow hydrodynamics

Hansen, Jesper Schmidt; Dyre, Jeppe C.; Daivis, Peter J.; Todd, B. D.; Bruus, Henrik

doi:10.1103/physreve.84.036311

Cited by 35 publications

(39 citation statements)

References 33 publications

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“…The influence of this methodological difference manifests especially for narrow tubes. (2) Kannam et al measured the flow enhancement using the slip length predicted by using the equilibrium MD method 45,46 and shear viscosity of bulk water.…”

Section: A Thermostatting Approachmentioning

confidence: 99%

Water flow in carbon nanotubes: The effect of tube flexibility and thermostat

Sam

Kannam

Hartkamp

et al. 2017

The Journal of Chemical Physics

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Although the importance of temperature control in nonequilibrium molecular dynamics simulations is widely accepted, the consequences of the thermostatting approach in the case of strongly confined fluids are underappreciated. We show the strong influence of the thermostatting method on the water transport in carbon nanotubes (CNTs) by considering simulations in which the system temperature is controlled via the walls or via the fluid. Streaming velocities and mass flow rates are found to depend on the tube flexibility and on the thermostatting algorithm, with flow rates up to 20% larger when the walls are flexible. The larger flow rates in flexible CNTs are explained by a lower friction coefficient between water and the wall. Despite the lower friction, a larger solid-fluid interaction energy is found for flexible CNTs than for rigid ones. Furthermore, a comparison of thermostat schemes has shown that the Berendsen and Nosé-Hoover thermostats result in very similar transport rates, while lower flow rates are found under the influence of the Langevin thermostat. These findings illustrate the significant influence of the thermostatting methods on the simulated confined fluid transport. Published by AIP Publishing. [http://dx

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Section: A Thermostatting Approachmentioning

confidence: 99%

Water flow in carbon nanotubes: The effect of tube flexibility and thermostat

Sam

Kannam

Hartkamp

et al. 2017

The Journal of Chemical Physics

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“…Good agreement between the ENS equation and molecular dynamics simulation data has been found 15,18 for fluids flowing in nano-slit pores.…”

Section: Introductionmentioning

confidence: 61%

“…3,6,7 The fact that there exists a coupling between the molecular intrinsic (or spin) angular momentum and the hydrodynamical degrees of freedom has long been known. [8][9][10][11][12][13] Recently, the coupling has been shown to reduce the flow rate in highly confined geometries, 14,15 that it is the mechanism behind flow generation when a rotating electrical field is applied across a channel, 14,16 and that it can be utilized to perform plane wave pumping. 17 The coupling is described by an extension of the Navier-Stokes (ENS) equations, 9,10,13 in which a) jschmidt@ruc.dk.…”

Section: Introductionmentioning

confidence: 99%

Generalized extended Navier-Stokes theory: Correlations in molecular fluids with intrinsic angular momentum

Hansen

Daivis

Dyre

et al. 2013

The Journal of Chemical Physics

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The extended Navier-Stokes theory accounts for the coupling between the translational and rotational molecular degrees of freedom. In this paper, we generalize this theory to non-zero frequencies and wavevectors, which enables a new study of spatio-temporal correlation phenomena present in molecular fluids. To discuss these phenomena in detail, molecular dynamics simulations of molecular chlorine are performed for three different state points. In general, the theory captures the behavior for small wavevector and frequencies as expected. For example, in the hydrodynamic regime and for molecular fluids with small moment of inertia like chlorine, the theory predicts that the longitudinal and transverse intrinsic angular velocity correlation functions are almost identical, which is also seen in the molecular dynamics simulations. However, the theory fails at large wavevector and frequencies. To account for the correlations at these scales, we derive a phenomenological expression for the frequency dependent rotational viscosity and wavevector and frequency dependent longitudinal spin viscosity. From this we observe a significant coupling enhancement between the molecular angular velocity and translational velocity for large frequencies in the gas phase; this is not observed for the supercritical fluid and liquid state points.

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“…The continuum-based methods have also not been found to be very accurate for more general problems involving flows with non-Newtonian fluids; complex boundaries; significant microscopic interactions or high Knudsen number including micro and nano-fluidics. In particular, nanodevices, microfluids and nanofluids demand better understanding and accounting of the atomistic details at the interfaces because of increased interfacial effects where assumptions of the continuum description of fluids are no longer valid [1] and the thermal fluctuations can no longer be neglected [2]. This effort aims at addressing some of these limitations of continuum based CFD methods by introducing a multiscale framework for a hybrid MD and CFD approach to modeling heat transfer in fluid flow.…”

Section: Multiscale Methodsmentioning

confidence: 99%

“…An all-atom model of octane assigns to each atom a set of parameters (FF parameters), which describe how the atom interacts with the other atoms within the molecule (bonded interactions: bond, angle, and dihedral parameters) as well as with atoms belonging to other molecules (non-bonded interactions: Coulomb and Lennard-Jones). The bonded interactions contribution to the potential energy of the system comes from harmonic bond stretching, ( − ) 2 , harmonic bond bending ( − ) 2 , and the torsional energy for a dihedral angle defined by four bonded atoms, (0) + (1) (1 + cos ) + (2) (1 − cos 2 ) + (3) (1 + cos 3 ). Here and are the spring constants in the harmonic description pf bond stretching and angle bending, respectively; and DISTRIBUTION STATEMENT A: Approved for public release.…”

Section: Introductionmentioning

confidence: 99%