Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theoretical study of the flow in a fluid damper containing high
  viscosity silicone oil: effects of shear-thinning and viscoelasticity   The flow inside a fluid damper where a piston reciprocates sinusoidally
inside an outer casing containing high-viscosity silicone oil is simulated
using a Finite Volume method, at various excitation frequencies. The oil is
modelled by the Carreau-Yasuda (CY) and Phan-Thien \& Tanner (PTT) constitutive
equations. Both models account for shear-thinning but only the PTT model
accounts for elasticity. The CY and other generalised Newtonian models have
been previously used in theoretical studies of fluid dampers, but the present
study is the first to perform full two-dimensional (axisymmetric) simulations
employing a viscoelastic constitutive equation. It is found that the CY and PTT
predictions are similar when the excitation frequency is low, but at medium and
higher frequencies the CY model fails to describe important phenomena that are
predicted by the PTT model and observed in experimental studies found in the
literature, such as the hysteresis of the force-displacement and force-velocity
loops. Elastic effects are quantified by applying a decomposition of the damper
force into elastic and viscous components, inspired from LAOS (Large Amplitude
Oscillatory Shear) theory. The CY model also overestimates the damper force
relative to the PTT, because it underpredicts the flow development length
inside the piston-cylinder gap. It is thus concluded that (a) fluid elasticity
must be accounted for and (b) theoretical approaches that rely on the
assumption of one-dimensional flow in the piston-cylinder gap are of limited
accuracy, even if they account for fluid viscoelasticity. The consequences of
using lower-viscosity silicone oil are also briefly examined.

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The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
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The categories of this paper are: solv-int