Temperature gradient-induced fluid pumping inside a single-wall carbon nanotube: A non-equilibrium molecular dynamics study

Faraji, Fahim; Rajabpour, Ali

doi:10.1063/1.4962308

Cited by 13 publications

(3 citation statements)

References 22 publications

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“…This pressure is suspected because the authors incorrectly used the virial equation for the scalar pressure to calculate the local pressure tensor in an inhomogeneous phase. A similar mistake was also made in ref .…”

Section: Resultssupporting

confidence: 56%

Microscopic Pressure Tensor in Cylindrical Geometry: Pressure of Water in a Carbon Nanotube

Shi

Shen

Santiso

et al. 2020

J. Chem. Theory Comput.

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The microscopic pressure tensor plays an important role in understanding the mechanical stability, transport, and high-pressure phenomena of confined phases. The lack of an exact formulation to account for the long-range Coulombic contribution to the local pressure tensor in cylindrical geometries prevents the characterization of molecular fluids confined in cylindrical pores. To address this problem, we first derive the local cylindrical pressure tensor for Lennard-Jones fluids based on the Harasima (H) definition, which is expected to be compatible with the Ewald summation method. The test of the H-definition pressure equations in a homogeneous system shows that the radial and azimuthal pressure have unphysical radial dependence near the origin, while the axial pressure gives physically meaningful values. We propose an alternative contour definition that is more appropriate for cylindrical geometry and show that it leads to physically realistic results for all three pressure tensor components. With this definition, the radial and azimuthal pressures are of Irving–Kirkwood (IK) type, and the axial pressure is of Harasima type. Because of the practical interest in the axial pressure, we develop a Harasima/Ewald (H/E) method for calculating the long-range Coulombic contribution to the local axial pressure for rigid molecules. As an application, the axial pressure profile of water inside and outside a (20, 20) single-wall carbon nanotube is determined. The H/E method is compared to the IK method, which assumes a spherically truncated Coulombic potential. Detailed analysis of the pressure profile by both methods shows that the water confined in the nanotube is in a stretched state overall in the axial direction.

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Section: Resultssupporting

confidence: 56%

Microscopic Pressure Tensor in Cylindrical Geometry: Pressure of Water in a Carbon Nanotube

Shi

Shen

Santiso

et al. 2020

J. Chem. Theory Comput.

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“…Additionally, CNT is rigid with a nano‐hollow structure, so it can be considered as a nano‐Helmholtz cavity. Due to the fact that CNTs are excellent thermal conductors in the axial direction, [ 34 ] along with the thermal conduction, the compressed air expands in nano‐Helmholtz cavity, as shown in Figure 1c. Since the light intensity is modulated with a frequency of f 0 , the compressed air presents a to‐and‐fro movement inside CNTs with the same frequency.…”

Section: Resultsmentioning

confidence: 99%

High Efficiency and Anomalous Photoacoustic Behavior in Vertical CNTs Array

Wang

Jiang

et al. 2022

Energy & Environ Materials

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Miniaturized sound generators are attractive to realize intriguing functions. Thermoacoustic device's application is seriously limited due to the frequency‐doubling phenomenon. To address this issue, photoacoustic sound generator is considered as a promising alternative. Here, based on vertical single‐wall carbon nanotubes (CNTs) array, we introduce a photoacoustic sound generator with internal nano‐Helmholtz cavity. Different from traditional device that generates sound by periodically heating up the open space air around material, this sound generator produces an audio signal by forming a forced vibration of the air inside the CNTs. Interestingly, anomalous photoacoustic behavior is observed that the sound pressure level (SPL) curve has a resonance peak, the corresponding frequency of which is inversely proportional to the CNTs array’s height. Furthermore, the energy conversion efficiency of this photoacoustic device is 1.64 times as large as that of a graphene sponge‐based photoacoustic device. Most importantly, this device can be employed for music playing, bringing a new clew for the development of musical instruments in the future.

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“…Although determining the thermophysical properties of nanofluids experimentally offers noteworthy results, using other methods such as computer simulations along with experimental methods have been very efficient in increasing our understanding of nanofluids. − Molecular dynamics (MD) is a computer simulation method in which Newton’s equations of motion are solved for a system of interacting particles to determine trajectories of atoms and molecules, and interparticle forces and their potential energies are computed by applying interatomic potentials or molecular mechanics force fields. Hence, many researchers utilized MD simulation to study the rheological properties of nanofluids. − Lu and Fan investigated the effects of volume fraction and size of Al 2 O 3 nanoparticles on the dynamic viscosity of water- and ethylene-glycol-based nanofluids.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation and Molecular Dynamics Simulations of Viscosity of CNT-Water Nanofluid at Different Temperatures and Volume Fractions of Nanoparticles

2018

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The viscosity of nanofluids, and consequently their energy dissipation, is a challenging factor in real applications because it affects the pressure drop and pumping power of equipment in industries. The aim of this experimental and simulation study is to measure and calculate the viscosity of a carbon nanotube (CNT)− water nanofluid by employing a rotational viscometer and by molecular dynamics (MD) simulation. The effects of temperature, solid concentration, and CNT diameter on the dynamic viscosity were examined within the temperature and volume concentration ranges of 25−65 °C and 0.125%−1%, respectively. Interestingly, the maximum observed increase in the relative viscosity of CNT−water nanofluid occurred at 65 °C, whereas the absolute viscosity of the nanofluid was minimum at this temperature. It was further found that the dynamic viscosity increases with increasing volume fraction of nanoparticles and with decreasing nanofluid temperature, whereas changing the diameter of the CNT does not have a significant effect on nanofluid viscosity. Furthermore, a correlation function was proposed in terms of solid concentration and nanofluid temperatures based on the MD simulation results, and its accuracy was investigated by analyzing the margin of deviation. The findings of this study are useful for industrial applications of CNT/water nanofluids.

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Temperature gradient-induced fluid pumping inside a single-wall carbon nanotube: A non-equilibrium molecular dynamics study

Cited by 13 publications

References 22 publications

Microscopic Pressure Tensor in Cylindrical Geometry: Pressure of Water in a Carbon Nanotube

Microscopic Pressure Tensor in Cylindrical Geometry: Pressure of Water in a Carbon Nanotube

High Efficiency and Anomalous Photoacoustic Behavior in Vertical CNTs Array

Experimental Investigation and Molecular Dynamics Simulations of Viscosity of CNT-Water Nanofluid at Different Temperatures and Volume Fractions of Nanoparticles

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