... process. The present section discusses molecular-based models and their relation to
the continuum models previously considered.
The most fundamental of the molecular models is deterministic. The motion ... Isotropic
Fluid,” J. Fluids Eng. 117, pp. 3 5.
Gad- el- Hak, M. (1999) The Fluid Mechanics of Microdevices: The Freeman Scholar Lecture,” J. Fluids
Eng. 121, pp. 5 33 .
G...
... polysilicon, electroplated nickel, and A- 533 B steel. These are
from microspecimens tested in the author’s laboratory.
20 m
(a)
(
b
)
FIGURE 3. 12 Microstructure of two common MEMS materials. Note the ... films fabricated in the
shapes of beams and plates by comparing the measured curvatures. These were two-layer composite
Mechanical Properties of MEMS Materials 3- 9
1 mm
FIG...
... and
σ
T
are the tangential momentum and thermal accommodation coef-
ficients respectively. The accommodation coefficients model the momentum and energy exchange of gas mol-
ecules impinging on the walls. ... of the membrane. We see that a two-
to three-orders of magnitude speed-up can be obtained using the graph-based algorithm.
5 .3. 3 The Structural Simulator
The membrane of...
... of the Navier–Stokes equations, as well as the molecular interaction models of the MD and the
DSMC methods. Although it may seem that the molecular simulation methods are more fundamental, they
require ... particularly important for simulation of gas flows in MEMS components.
If we consider a micromotor or a micro-comb-drive mechanism, gas flow in most of the device can be
simul...
... and Ducts at Micro and Nano
Scales,” Microscale Thermophys. Eng. 3, p. 43.
Beskok, A. (2002) “Molecular-Based Microfluidic Simulation Models,” in Handbook of MEMS, 1st ed.,
M. Gad- el- Hak, ed., CRC ... above Mach numbers of approximately two. Furthermore, the application of the
1 3- or 35 -moment systems to three-dimensional problems remains computationally prohibitive at pr...
... dynamics models beyond
Navier–Stokes are needed. These models are known as extended, or generalized, hydrodynamics models
in the literature. Some of these models are the Burnett equations; 1 3- moment ... m. The first-order
8-2 8 MEMS: Introduction and Fundamentals
y/y
max
0.0
0.5
1.0
0.0 1.0 2.0 3. 0 4.0 5.0
x/y
max
FIGURE 8.29
Microchannel geometry and grid.
y/y
max
1.0
0.5
0...
... Taylor & Francis Group, LLC
1 1-2 MEMS: Introduction and Fundamentals
attention of MEMS researchers since the early days of MEMS development, and there have been several
demonstrations of micromotors ... field). Sample ions migrate from
the high-field–high-drift-velocity of the sample region to the low-field–low-drift-velocity region and
accumulate, or stack, at the i...
... Because the MEMS constraint is the minimum gap dimension, the wave bearing
in a MEMS machine can be implemented only by selectively enlarging the bearing gap. Piekos (2000) ana-
lyzed the performance ... along with the
theoretical predictions based on the assumed geometry. The right-hand frame shows the same measurements compared
with the same model but using slightly...