Molecular dynamics simulationof nanofluidics and nanomachining
M. T. Horsch,1, 4 S. Stephan,1 S. Becker,1 M. Heier,1 M. P. Lautenschläger,1
F. Diewald,2 R. Müller,2 H. M. Urbassek,3 and H. Hasse1
1Engineering Thermodynamics, 2Applied Mechanics, 3Computational Materials Science, University of Kaiserslautern, Germany,4Chemical Engineering, IIT Kanpur, India
HPC & Big Data in Molecular EngineeringHiPC 2016, Hyderabad, December 19, 2016
NEMD simulation of heat transfer
2Dec 19, 2016
Dual-control-volume1 non-equilibrium molecular dynamics simulation:
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
1T. Ikeshoji, B. Hafskjold, Mol. Phys. 81, 251, 1994.
T * T *
q * q *
LJTS fluid
Δy = 20 σ
λ* = 5.5 λ* = 5.9
0.15
– 0.15 – 0.16
0.160.728 0.813
0.8990.813
y
NEMD simulation of momentum transfer
3Dec 19, 2016
By NEMD simulation, both linear and non-linear effects are accessible.
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Hardy stress tensor: J. Vanegas, A. Torres, M. Arroyo, J. Chem. Theory Comput. 10, 691, 2014.
yy
NEMD simulation of momentum transfer
4Dec 19, 2016
To compute the stress, kinetic and virial contributions are resolved locally.1, 2
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
1Hardy stress tensor: J. Vanegas, A. Torres, M. Arroyo, J. Chem. Theory Comput. 10, 691, 2014.
y
2MD simulation code ls1 mardyn available at http://www.ls1-mardyn.de/
loca
l pre
ssu
relo
cal d
ensi
ty
NEMD simulation of diffusive mass transfer
5Dec 19, 2016
Avendaño’s dæmon,1 based on virtual colouring of identical molecules, induces ∇μ without the simultaneous presence of a pressure gradient by accelerating differently coloured molecules in opposite directions.
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
In this way, diffusive mass transfer is separated from momentum transfer.1H. Frentrup, C. Avendaño, M. Horsch, A. Salih, E. A. Müller, Mol. Sim. 38, 540, 2012.
NEMD simulation of Poiseuille flow
6Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
NEMD simulation of Poiseuille flow
7Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
NEMD simulation of Poiseuille flow
8Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Methane at a graphite wall: Presence of slip
9Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Water in a polar membrane: Absence of slip
10Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Contact angle and fluid-wall interaction
11Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Correlation of the density profile by
ρ(r, y) = f(r) · [h(y) + 1],
with the exponential decay term h(y)
and a hyperbolic tangent profile f(r).
LJTS potential for fluid (f) and wall (w) with σfw
= σf und ε
w = 100 ε
f.
Variation of the temperature T and the fluid-wall dispersion by ζ = εfs / ε
f.
S. Becker et al., Langmuir 30, 13606, 2014
Contact angle and fluid-wall interaction
12Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Variation of the reduced fluid-wall dispersion energy ζ, at constant T:
Correlation: cos θ proportional to ζ – ζ0 for ζ
0 = 0.52 at all temperatures.
solvophilic
θ < 90°
solvophobicθ > 90°
LJTS
T = 0.7 ε
T = 0.8 ε
T = 0.9 ε
T = 0.95 ε
T = 1.0 ε
cos
θ
ζ0 ζ
S. Becker et al., Langmuir 30, 13606, 2014
θ < 90°
θ > 90°
Contact angle and fluid-wall interaction
13Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
1S. Becker, H. M. Urbassek, M. Horsch, and H. Hasse, Langmuir 30, 13606, 2014.
At high temperatures, (pre-)critical wetting occurs:
LJTS wall withσ
s = σ
f and
ρs = 1.07 σ
f
-3
reduced fluid-wall dispersion energy
T / Tc
solvophilicθ < 90°
solvophobicθ > 90°
wet (0°)
dry(180°)
ζ0
Correlation:1 cos θ proportional to ζ – ζ0 and to ( 1 – T/T
c )–2/3
+ 1.
NEMD simulation of Couette shear flow
14Dec 19, 2016
Scenario: Fluid and wall as LJTS with ε
w = 100 ε
f and σ
w = σ
f
Tw = 0.8 ε
f
Δyw = 15 σ
f
Δv
w = 0.5 (ε
f / m
f )1/2
Fluid attracted more strongly to the walls supports greater shear rates without boundary slip. A stronger unlike interactionbetween the fluid and the wallimproves heat transfer fromthe fluid to the wall.
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
T
T
y
yy
y
vx
vx
ε fw =
0.0
5 ε
fε fw
= 0
.5 ε
f
Nanomachining with a rigid nanoindenter1, 2
15Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Fe
2Y. Gao, H. M. Urbassek, Appl. Surf. Sci. 389, 688, 2016.
1Y. Gao et al., Comput. Mater. Sci. 103, 77, 2015.
Nanomachining in the presence of a liquid
16Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Fe
Nanomachining in the presence of a liquid
17Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Thermostat acting on remotepart of the work piece,
Text
= 0.8 εf ,
fluid density ρf = 0.8 σ
–3.
Fluid and fluid-solid: LJTS
Fluid-solid: ζ = 0.5
Iron: Mendelev potential1
Indenter: Rigid cylinder (with LJTS sites)
1M. Mendelev, S. Han, D. Srolovitz, G. Ackland, D. Sun, M. Asta, Philos. Mag. 83, 3977, 2003.
Fe
Indentation in the presence of a liquid
18Dec 19, 2016
Fluid and fluid-solid: LJTS
Fluid-solid: ζ = 0.5
Iron: Mendelev potential
Indenter: Rigid cylinder (with LJTS sites)
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Thermostat acting on remotepart of the work piece,
Text
= 0.8 εf ,
fluid density ρf = 0.8 σ
–3.
Scratching in the presence of a liquid
19Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
The LJTS fluid with ζ = 0.5 does not lubricate the nanomachining process.
Heat transfer from work piece to liquid
20Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
MD simulation of indenta-tion and scratching withdifferent orders of magni-tude for the fluid-solid in-teraction.
scratching
indentation
Tflu
id /
ε fluid
[Å]
ζ = 0.05
ζ = 0.5
temperature profile (ζ = 0.5)
Heat transfer from work piece to liquid
21Dec 19, 2016
Greater fluid-wall dispersion
● reduces Kapitza (thermal) resistancehere, by 10 to 50%, depending on T
● increases friction → no lubrication by LJhere, F
T /F
N increased by 20 to 30%
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
MD simulation of indenta-tion and scratching withdifferent orders of magni-tude for the fluid-solid in-teraction.
scratching
indentation
Tflu
id /
ε fluid
[Å]
ζ = 0.05
ζ = 0.5
temperature profile (ζ = 0.5)
Morphology as a challenge for data science
22Dec 19, 2016
Physical and chemical inhomogeneities influence adsorption and wetting.
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Nanoscopic Poiseuille flow: Results
23Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Nano- to microfluidics by scale-bridging MD
24Dec 19, 2016 M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Scale bridging by mesoscopic approaches
25Dec 19, 2016
Relaxation simulations based on a square-gradient phase field model:1
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
1F. Diewald, C. Kuhn, R. Blauwhoff, M. Heier, S. Becker, S. Werth, M. Horsch, H. Hasse, and R. Müller, Proc. Appl. Math. Mech. 16, 519, 2016.
φ = –M ∇ Aφ
Allen-Cahn
Scale bridging by mesoscopic approaches
26Dec 19, 2016
Relaxation simulations based on a square-gradient phase field model:1
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse
Future aims:
● Include inertia, external driving forces, non-equilibrium steady states● Consider fluctuations, e.g. on the basis of fluctuating hydrodynamics
1F. Diewald, C. Kuhn, R. Blauwhoff, M. Heier, S. Becker, S. Werth, M. Horsch, H. Hasse, and R. Müller, Proc. Appl. Math. Mech. 16, 519, 2016.
φ = –M ∇ Aφ
Allen-Cahn
Conclusion
27Dec 19, 2016
The increasing availability of HPC resources enables molecular simulationto capture the transition from nano- to microfluidics at an atomistic level. This is still expensive and does not make mesoscopic methods redundant. Instead, it helps to validate theories and mesoscopic models.
For phenomena involving fluid-solid contact, the challenge to modelling and data science consists in reducing the complexity of the fluid-solid interaction and surface morphology, retaining physically relevant features.
Example: The single-centre LJTS model captures the influence of the fluid-solid dispersion energy on the contact angle, the boundary slip length, and the Kapitza (thermal) resistance; all decrease as ζ increases.
However, no lubrication was found: Increased wetting of a model work piece by the LJTS fluid was found to increase the friction coefficient.
M. Horsch, S. Stephan, S. Becker, M. Heier, M. Lautenschläger, F. Diewald, R. Müller, H. Urbassek, H. Hasse