Inertial effects in adiabatically driven flashing ratchets

Microplastic (MP) debris is recognized to be one of the most serious threats to marine environments. They are found in all seas and oceanic basins worldwide, even in the most remote areas. This is further proof that the transport of MPs is very efficient. In the present study, we focus our attention on MPs’ transport owing to the Stokes drift generated by sea waves. Recent studies have shown that the interaction between heavy particles and Stokes drift leads to unexpected phenomena mostly related to inertial effects. We perform a series of laboratory experiments with the aim to directly measure MPs’ trajectories under different wave conditions. The main objective is to quantify the inertial effect and, ultimately, suggest a new analytical formulation for the net settling velocity. The latter formula might be implemented in a larger scale transport model in order to account for inertial effects in a simplified approach.

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Inertial focusing and zeta potential measurements of single-nanoparticles using octet-nanochannels

Lab on a Chip ◽

10.1039/d1lc00239b ◽

2021 ◽

Author(s):

Shohei Kishimoto ◽

Makusu Tsutsui ◽

Kazumichi Yokota ◽

Masateru Taniguchi

Keyword(s):

Zeta Potential ◽

Inertial Effects ◽

Inertial Focusing ◽

Particle Focusing ◽

Single Nanoparticle

Electrokinetics in octet nanochannels was demonstrated to enable particle focusing via inertial effects to accurate single-nanoparticle zeta-potential measurements.

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Applicability of a Three-Layer Model for the Dynamic Analysis of Ballasted Railway Tracks

Vibration ◽

10.3390/vibration4010013 ◽

2021 ◽

Vol 4 (1) ◽

pp. 151-174

Author(s):

André F. S. Rodrigues ◽

Zuzana Dimitrovová

Keyword(s):

Mechanical Properties ◽

Finite Element ◽

Dynamic Analysis ◽

Shear Stiffness ◽

Shear Resistance ◽

Railway Track ◽

Fe Model ◽

Inertial Effects ◽

Layer Model ◽

3D Finite Element

In this paper, the three-layer model of ballasted railway track with discrete supports is analyzed to access its applicability. The model is referred as the discrete support model and abbreviated by DSM. For calibration, a 3D finite element (FE) model is created and validated by experiments. Formulas available in the literature are analyzed and new formulas for identifying parameters of the DSM are derived and validated over the range of typical track properties. These formulas are determined by fitting the results of the DSM to the 3D FE model using metaheuristic optimization. In addition, the range of applicability of the DSM is established. The new formulas are presented as a simple computational engineering tool, allowing one to calculate all the data needed for the DSM by adopting the geometrical and basic mechanical properties of the track. It is demonstrated that the currently available formulas have to be adapted to include inertial effects of the dynamically activated part of the foundation and that the contribution of the shear stiffness, being determined by ballast and foundation properties, is essential. Based on this conclusion, all similar models that neglect the shear resistance of the model and inertial properties of the foundation are unable to reproduce the deflection shape of the rail in a general way.

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The appearance of boundary layers and drift flows due to high-frequency surface waves

Journal of Fluid Mechanics ◽

10.1017/jfm.2012.293 ◽

2012 ◽

Vol 707 ◽

pp. 482-495 ◽

Cited By ~ 24

Author(s):

Ofer Manor ◽

Leslie Y. Yeo ◽

James R. Friend

Keyword(s):

Boundary Layer ◽

Surface Waves ◽

High Frequency ◽

Slip Boundary Condition ◽

Inertial Effects ◽

Velocity Amplitude ◽

Slip Boundary ◽

Long Period ◽

Bulk Waves ◽

Schlichting Streaming

AbstractThe classical Schlichting boundary layer theory is extended to account for the excitation of generalized surface waves in the frequency and velocity amplitude range commonly used in microfluidic applications, including Rayleigh and Sezawa surface waves and Lamb, flexural and surface-skimming bulk waves. These waves possess longitudinal and transverse displacements of similar magnitude along the boundary, often spatiotemporally out of phase, giving rise to a periodic flow shown to consist of a superposition of classical Schlichting streaming and uniaxial flow that have no net influence on the flow over a long period of time. Correcting the velocity field for weak but significant inertial effects results in a non-vanishing steady component, a drift flow, itself sensitive to both the amplitude and phase (prograde or retrograde) of the surface acoustic wave propagating along the boundary. We validate the proposed theory with experimental observations of colloidal pattern assembly in microchannels filled with dilute particle suspensions to show the complexity of the boundary layer, and suggest an asymptotic slip boundary condition for bulk flow in microfluidic applications that are actuated by surface waves.

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