Wave trapping by dual porous barriers near a wall in the presence of bottom undulation

2017 ◽  
Vol 16 (3) ◽  
pp. 286-297 ◽  
Author(s):  
R. B. Kaligatla ◽  
Manisha ◽  
T. Sahoo
Keyword(s):  
Wave Trapping ◽  
Bottom Undulation ◽  
Porous Barriers

scholarly journals Wave trapping and E × B staircases

2021 ◽  
Vol 28 (4) ◽  
pp. 042302
Author(s):  
X. Garbet ◽  
O. Panico ◽  
R. Varennes ◽  
C. Gillot ◽  
G. Dif-Pradalier ◽  
...  
Keyword(s):  
Wave Trapping

scholarly journals Evolution and Vertical Structure of an Undular Bore Observed on 20 June 2015 during PECAN

2017 ◽  
Vol 145 (9) ◽  
pp. 3775-3794 ◽  
Author(s):  
Dana Mueller ◽  
Bart Geerts ◽  
Zhien Wang ◽  
Min Deng ◽  
Coltin Grasmick
Keyword(s):  
Life Cycle ◽  
University Of Wyoming ◽  
Cold Pool ◽  
Undular Bore ◽  
Wave Trapping ◽  
Hydraulic Theory ◽  
The University ◽  
Second Wave ◽  
Scorer Parameter ◽  
Equal Amplitude

This study documents the evolution of an impressive, largely undular bore triggered by an MCS-generated density current on 20 June 2015, observed as part of the Plains Elevated Convection at Night (PECAN) experiment. The University of Wyoming King Air with profiling nadir- and zenith-viewing lidars sampled the south-bound bore from the time the first bore wave emerged from the nocturnal convective cold pool and where updrafts over 10 m s−1 and turbulence in the wave’s wake were encountered, through the early dissipative stage in which the leading wave began to lose amplitude and speed. Through most of the bore’s life cycle, its second wave had a higher or equal amplitude relative to the leading wave. Striking roll clouds formed in wave crests and wave energy was detected to about 5 km AGL. The upstream environment indicates a negative Scorer parameter region due to flow reversal at midlevels, providing a wave trapping mechanism. The observed bore strength of 2.4–2.9 and speed of 15–16 m s−1 agree well with values predicted from hydraulic theory. Surface and profiling measurements collected later in the bore’s life cycle, just after sunrise, indicate a transition to a soliton.

scholarly journals Temperature-controlled MPa-pressure ultrasonic cell manipulation in a microfluidic chip

Lab on a Chip ◽  
2015 ◽  
Vol 15 (16) ◽  
pp. 3341-3349 ◽  
Author(s):  
Mathias Ohlin ◽  
Ida Iranmanesh ◽  
Athanasia E. Christakou ◽  
Martin Wiklund
Keyword(s):  
Lung Cancer ◽  
High Pressure ◽  
Cancer Cells ◽  
Microfluidic Chip ◽  
Acoustic Streaming ◽  
Cell Manipulation ◽  
Wave Trapping ◽  
Ultrasonic Standing Wave ◽  
Temperature Controlled

We study the effect of 1 MPa-pressure ultrasonic-standing-wave trapping of cells during one hour in a fully temperature- and acoustic streaming-controlled microfluidic chip, and conclude that the viability of lung cancer cells are not affected by this high-pressure, long-term acoustophoresis treatment.

scholarly journals On the scattering of waves by nearly hard or soft incomplete vertical barriers in water of infinite depth

1998 ◽  
Vol 39 (3) ◽  
pp. 293-307
Author(s):  
P. F. Rhodes-Robinson
Keyword(s):  
Perturbation Theory ◽  
Infinite Depth ◽  
Hard Limit ◽  
Vertical Barriers ◽  
Progressive Waves ◽  
Porous Barriers

AbstractIn this paper the scattered progressive waves are determined due to progressive waves incident normally on certain types of partially immersed and completely submerged vertical porous barriers in water of infinite depth. The forms are approximate only, and are obtained using perturbation theory for nearly hard or soft barriers having high and low porosities respectively. The results for arbitrary porosity are difficult to obtain, in contrast to the well known hard limit of impermeable barriers.

Profile measurement using standing wave trapping

2011 ◽  
Author(s):  
Taisuke Washitani ◽  
Masaki Michihata ◽  
Terutake Hayashi ◽  
Yasuhiro Takaya
Keyword(s):  
Standing Wave ◽  
Profile Measurement ◽  
Wave Trapping

On the irreversibility of internal-wave dynamics due to wave trapping by mean flow inhomogeneities. Part 1. Local analysis

1993 ◽  
Vol 251 ◽  
pp. 21-53 ◽  
Author(s):  
Sergei I. Badulin ◽  
Victor I. Shrira
Keyword(s):  
Shear Flow ◽  
Internal Wave ◽  
Wave Field ◽  
Large Scale ◽  
Spatial Scales ◽  
Energy Concentration ◽  
Local Analysis ◽  
Mean Flow ◽  
Wave Trapping ◽  
Wave Dynamics

The propagation of guided internal waves on non-uniform large-scale flows of arbitrary geometry is studied within the framework of linear inviscid theory in the WKB-approximation. Our study is based on a set of Hamiltonian ray equations, with the Hamiltonian being determined from the Taylor-Goldstein boundary-value problem for a stratified shear flow. Attention is focused on the fundamental fact that the generic smooth non-uniformities of the large-scale flow result in specific singularities of the Hamiltonian. Interpreting wave packets as particles with momenta equal to their wave vectors moving in a certain force field, one can consider these singularities as infinitely deep potential holes acting quite similarly to the ‘black holes’ of astrophysics. It is shown that the particles fall for infinitely long time, each into its own ‘black hole‘. In terms of a particular wave packet this falling implies infinite growth with time of the wavenumber and the amplitude, as well as wave motion focusing at a certain depth. For internal-wave-field dynamics this provides a robust mechanism of a very specific conservative and moreover Hamiltonian irreversibility.This phenomenon was previously studied for the simplest model of the flow non-uniformity, parallel shear flow (Badulin, Shrira & Tsimring 1985), where the term ‘trapping’ for it was introduced and the basic features were established. In the present paper we study the case of arbitrary flow geometry. Our main conclusion is that although the wave dynamics in the general case is incomparably more complicated, the phenomenon persists and retains its most fundamental features. Qualitatively new features appear as well, namely, the possibility of three-dimensional wave focusing and of ‘non-dispersive’ focusing. In terms of the particle analogy, the latter means that a certain group of particles fall into the same hole.These results indicate a robust tendency of the wave field towards an irreversible transformation into small spatial scales, due to the presence of large-scale flows and towards considerable wave energy concentration in narrow spatial zones.

Wave scattering by porous bottom undulation in a two layered channel

2014 ◽  
Vol 13 (4) ◽  
pp. 355-361 ◽  
Author(s):  
Sandip Paul ◽  
Soumen De
Keyword(s):  
Wave Scattering ◽  
Bottom Undulation

scholarly journals Electron beam relaxation in inhomogeneous plasmas

2013 ◽  
Vol 31 (8) ◽  
pp. 1379-1385 ◽  
Author(s):  
A. Voshchepynets ◽  
V. Krasnoselskikh
Keyword(s):  
Electron Beam ◽  
Beam Energy ◽  
Electron Beams ◽  
Inhomogeneous Plasma ◽  
Density Fluctuations ◽  
Langmuir Waves ◽  
Wave Trapping ◽  
Beam Plasma ◽  
Beam Plasma Instability ◽  
Accelerated Particles

Abstract. In this work, we studied the effects of background plasma density fluctuations on the relaxation of electron beams. For the study, we assumed that the level of fluctuations was so high that the majority of Langmuir waves generated as a result of beam-plasma instability were trapped inside density depletions. The system can be considered as a good model for describing beam-plasma interactions in the solar wind. Here we show that due to the effect of wave trapping, beam relaxation slows significantly. As a result, the length of relaxation for the electron beam in such an inhomogeneous plasma is much longer than in a homogeneous plasma. Additionally, for sufficiently narrow beams, the process of relaxation is accompanied by transformation of significant part of the beam kinetic energy to energy of accelerated particles. They form the tail of the distribution and can carry up to 50% of the initial beam energy flux.

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