flow of fluids and solids at the nanoscale thomas prevenslik qed radiations discovery bay, hong...

Flow of Fluids and Solids at the Nanoscale

Thomas Prevenslik

QED Radiations

Discovery Bay, Hong Kong, China

Proc. 2nd Conference on Heat Transfer Fluid Flow, HTTF'2015, 20-21 July, Barcelona

1

The Hagen-Poiseuille equation of classical fluid flow that assumes a no-slip condition at the wall cannot explain the

dramatic increase in flow found in nanochannels.

Even if slip is assumed at the wall, the calculated slip-lengths are found exceed the slip on non-wetting surfaces by 2 to 3

orders of magnitude.

Similarly, MD simulations of nanochannel flow cannot explain the flow enhancement.

MD = molecular dynamics.

Introduction(Fluids)


2

Introduction(Solids)


3

In solids, classical kMC cannot explain how crystals in a nanotube under the influence of an electric current flow through a constriction that is smaller than the crystal

kMC = kinetic Monte Carlo.

However, QM and not classical physics governs the nanoscale.

QM = quantum mechanics.

At the nanocale, fluid and solid atoms are placed under EM confinement that by QM requires their heat capacity

to vanish.

EM = electromagnetic.

QM v. Classical Physics

Unlike classical physics, QM precludes the conservation of viscous and frictional heat in fluid and solid atoms by the

usual increase in temperature.

MD and kMC based in classical physics therefore require modification for QM at the nanoscale.

Conservation of viscous and frictional heat proceeds by QED inducing creation of EM radiation that ionizes the atoms to cause atomic separation under

Coulomb charge repulsion.

QED = quantum electrodynamics.


4

Approach


5

MD simulations of liquid argon flow in a nanochannel show the viscosity to vanish suggesting the flow is upper bound by the

frictionless Bernoulli equation

Simplified extension of Bernoulli equation to the flow of a solid crystal through a nanotube suggests cohesion to vanish,

Fluid and solid at the nanoscale flow as a loosely bound collection of atoms under Coulomb repulsion

Heat capacity of the atom

TIR Confinement of Nanostructures

Conservation of energy and momentum

Theory


6

Heat Capacity of the Atom

7

kT 0.0258 eV

0.00001

0.0001

0.001

0.01

0.1

1 10 100 1000

Pla

nck

Ene

rgy

-E

-eV

Thermal Wavelength - l - microns

Classical Physics (MD, Comsol)


l

l1

kT

hcexp

hc

E

Classical Physics (MD, Comsol)

QM(kT = 0)

At the nanoscale, the atom has no heat capacity by QM

Nanostructures have high surface to volume ratio

Absorbed EM energy temporarily confines itself to the surface to form the TIR confinement

QED converts absorbed EM energy to standing waves that ionize the nanostructure or escape to surroundings

f = ( c/n) / / 2 = d E = h f

TIR Confinement

8Proc. 2nd Conference on Heat Transfer Fluid Flow, HTTF'2015, 20-21 July, Barcelona

Heat

dIonization

QED

Radiation

QED

Radiation

Surface Absorption / 2

Standing Wave

Conservation of Energy

Lack of heat capacity by QM precludes EM energy conservation in discrete molecules and nanostructures

by an increase in temperature, but how does conservation proceed?

ProposalAbsorbed EM energy is conserved by creating QED induced excitons (holon and electron pairs) at the TIR

resonance

Upon recombination, the excitons emit EM radiation that charges the molecule and nanostructure or is lost to the

surroundings.


9

Conservation of Momentum

Absorption of EM energy photon velocities vanish

Excitons are created at zero velocity

Momentum of photons = Momentum of excitons = 0

Momentum is conserved because EM energy is absorbed


10

Frictionless Fluids / Solids


Pot

enti

als

Atom

QEDCharge

Zero

Atom + QED Charge

QED charge makes atomic attraction vanish = 0

11

MD v. QM


12

MD assumes the atoms have thermal kT energy or the heat capacity to conserve EM energy by an increase in

temperature, but QM does not

QM requires the Nose-Hoover thermostat to maintain the model at constant absolute zero temperature.

Classically, temperature creates pressure. QM requires the temperature to create excitons and charge that

produces repulsive Coulomb forces between atoms.

MD Simulation


Usually, MD solutions of nanochannel flow are performed with Lees and Edwards periodic boundary conditions.

But charging the atoms requires long range corrections that may be avoided by using a discrete MD model and

considering all atoms without a cut-off in force computations

13

Lennard-Jones Potential


The L-J simulation of the atomic potential

s = repulsive = attractive

The L-J potential minimum occurs at R = 21/6

ULJ = - .

14

Electrostatic Force


15

The electrostatic energy UES from the QED induced charge

𝑈 𝐸𝑆=𝑒2

4𝑜𝑅

𝑐=𝑈𝐿𝐽

𝑈 𝐸𝑆

=421 /6𝑜

𝑒2

The fraction c of UES to counter the attractive potential

F= , < c The electrostatic repulsion force F between atoms

Temperature

Proc. 2nd Conference on Heat Transfer Fluid Flow, HTTF'2015, 20-21 July, Barcelona 16

MD simulations valid by QM require the viscous heat is not conserved by an increase in temperature

MD solutions are therefore made near absolute zero temperature, say 0.001 K to avoid temperature dependent

atom velocities.


The BCC configuration assumed a discrete 2D model of 100 atoms of liquid argon in a 32.6 A configuration.

17

Model

Loading


The MD loading was a velocity gradient normal to the flow of 100 m/s over the height of the MD box.

Unlike Lees-Edwards, the MD computation box is distorted after 25000 iterations

(Solution 150000 iterations)

18

The fraction c of the available electrostatic energy UES to counter the attractive potential is,

Taking = 120 k for argon, the fraction c = 0.0027.

MD Solution


MD Results


20

-10000 10000 30000 50000 70000 90000 110000 130000 150000-1.2E-03

-1.0E-03

-8.0E-04

-6.0E-04

-4.0E-04

-2.0E-04

0.0E+00

2.0E-04

4.0E-04

Iteration

Vis

cosi

ty [

Pa-

s]

MD solutions were obtained for various to determine the optimum at which the viscosity vanished

h = 0.0006 < c = 0.0027

Collectively, 4 pairs of atoms participated

in reducing 2 atom friction

Experimental Data

Proc. 2nd Conference on Heat Transfer Fluid Flow, HTTF'2015, 20-21 July, Barcelona 21

= QM / QM, 0

QM is the actual flow QM,0 is the Bernoulli equation

Conclusions


High flow in nanochannels is the consequence of QM that requires the heat capacity of the atom under EM confinement to vanish and negate the conservation of viscous heat by an

increase in temperature.

Instead, the viscous heat is conserved by QED inducing the creation of EM radiation that ionizes the fluid molecules to produce a state of Coulomb repulsion that overcomes the

attractive potential between atoms.

Nanochannels produce frictionless Bernoulli flow as the fluid viscosity vanishes and reasonably supports experiments.

Flow of Solids


Iron crystals under an electric current fit through a constriction in the nanochannel that is smaller than the crystal itself ?

23

Classical kMC atom has kT energy invalid by QM

But as kT 0, V 0, the crystal does not move.

kMC Solutions


Flow of metal crystals through smooth uniform nanochannels is generally thought caused by electromigration based on kMC

24

Analysis


Instead of temperature changes, QED conserves the Joule heat to charge all atoms in crystal

For a voltage difference V* acting across nanotube length L, the force F across a crystal atom of cubical dimension b

having charge q = unit electron charge,

F=q V∗

Lb

25

Bernoulli Equation


V=√ 2 P

=√2qV ∗

b L

The pressure P across the atom is, P = F / b2

giving the atom velocity V

Experiment V = 1.4 micron/s , L=2 micron, V* = 0.2 Volts

For iron, b =0.22 nm, = 7880 kg/m3 V = 135 microns/s 2 orders of magnitude higher !!!

Only 1% of crystal atoms are charged ? Fe (n=1.25) < CNT graphite (n=2.5) Rerun tests with Si (n=3.2) crystal ?

26

Questions & Papers

Email: [email protected]

http://www.nanoqed.org


27

http://www.nanoqed.org/

flow of fluids and solids at the nanoscale thomas prevenslik qed radiations discovery bay, hong...

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