scholarly journals Lagrangian Transport and Chaotic Advection in Three-Dimensional Laminar Flows

2021 ◽  
Author(s):  
Michel F. M. Speetjens ◽  
Guy Metcalfe ◽  
Murray Rudman
Keyword(s):  
Turbulent Flows ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Laminar Flows ◽  
Chaotic Advection ◽  
Systematic Analysis ◽  
Lagrangian Transport ◽  
Analysis And Design ◽  
Efficient Transport ◽  
Transport And Mixing

Abstract Transport and mixing of scalar quantities in fluid flows is ubiquitous in industry and Nature. Turbulent flows promote efficient transport and mixing by their inherent randomness. Laminar flows lack such a natural mixing mechanism and efficient transport is far more challenging. However, laminar flow is essential to many problems and insight into its transport characteristics of great importance. Laminar transport, arguably, is best described by the Lagrangian fluid motion ("advection") and the geometry, topology and coherence of fluid trajectories. Efficient laminar transport being equivalent to "chaotic advection" is a key finding of this approach. The Lagrangian framework enables systematic analysis and design of laminar flows. However, the gap between scientific insights into Lagrangian transport and technological applications is formidable primarily for two reasons. First, many studies concern two-dimensional (2D) flows yet the real world is three dimensional (3D). Second, Lagrangian transport is typically investigated for idealised flows yet practical relevance requires studies on realistic 3D flows. The present review aims to stimulate further development and utilisation of know-how on 3D Lagrangian transport and its dissemination to practice. To this end 3D practical flows are categorised into canonical problems. First, to expose the diversity of Lagrangian transport and create awareness of its broad relevance. Second, to enable knowledge transfer both within and between scientific disciplines. Third, to reconcile practical flows with fundamentals on Lagrangian transport and chaotic advection. This may be a first incentive to structurally integrate the "Lagrangian mindset" into the analysis and design of 3D practical flows.

The Construction of the Three-Dimensional Optimize Expert System of Oil-Immersed Pump Lectotype

2011 ◽  
Vol 80-81 ◽  
pp. 1000-1005
Author(s):  
Qiang Li ◽  
Jian Zhong Li
Keyword(s):  
Expert System ◽  
Software Design ◽  
Intelligent System ◽  
Three Dimensional ◽  
Oil Field ◽  
Synthetic Approach ◽  
Systematic Analysis ◽  
Analysis And Design ◽  
Engineering Control ◽  
Key Points

The applicability and accuracy of whole set oil-immersed pump lectotype are the key points to improve the recovery ratio of oil field and to conserve energy. This paper have conceived the construction and implementation of the expert system of whole set oil-immersed pump lectotype and discussed in several aspects: such as systematic analysis and design, the construction of engineering control platform, the development of plug-in software, the construction of intelligent system and the execution of software design and so on. It has integrated the synthetic approach with expert System of Whole Set Oil-immersed Pump lectotype.

A Tubular Cross-Flow Filtration Module Based on Chaotic Advection

2015 ◽  
Author(s):  
T. G. Kang ◽  
K. T. Park ◽  
S. U. Kim
Keyword(s):  
Turbulent Flows ◽  
Three Dimensional ◽  
Cross Flow ◽  
Operating Conditions ◽  
Membrane Module ◽  
Chaotic Advection ◽  
Thin Plates ◽  
Tubular Membrane ◽  
Cross Flow Filtration ◽  
Wide Range

We propose a tubular membrane module with embedded three-dimensional structures which is efficient in a wide range of operating conditions (covering both laminar and turbulent flows). Thin plates with barriers are inserted periodically in the circular channel geometry, leading to chaotic advection in a spatially periodic channel flow. Using a numerical scheme combining a particle-tracking and the finite element method, the insert geometry is optimized. The performance of the newly proposed membrane module is assessed by experiments. The membrane module with embedded inserts is found to be better in performance than an ordinary tubular membrane module.

scholarly journals TURBULENCE DRIVEN BY FARADAY SURFACE WAVES

2014 ◽  
Vol 34 ◽  
pp. 1460379 ◽  
Author(s):  
MICHAEL SHATS ◽  
NICOLAS FRANCOIS ◽  
HUA XIA ◽  
HORST PUNZMANN
Keyword(s):  
Turbulent Flows ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Spectral Energy ◽  
Vertical Acceleration ◽  
Faraday Waves ◽  
Frequency Spectra ◽  
Inverse Energy Cascade ◽  
Lagrangian Velocity ◽  
Measuring Frequency

We report experimental results which show that the particle motion on the surface perturbed by Faraday waves is similar to the fluid motion in 2D turbulence. It supports the inverse energy cascade or the spectral energy transfer from smaller to larger scales. The vertical acceleration ranges from the Faraday instability threshold up to the droplet nucleation threshold where the ripples are a couple of millimeters high. Such a configuration rules out any 2D assumption on the fluid motion. The motion of floaters on the surface of the Faraday waves is essentially three dimensional but its horizontal component shows unexpected analogy with two-dimensional turbulence. The presence of the inverse cascade is detected by measuring frequency spectra of the Lagrangian velocity and confirmed by computing the third moment of the horizontal Eulerian velocity fluctuations. This is a robust phenomenon observed in deep water in a broad range of flow energies and wavelengths. The emergence of such a phenomenology in Faraday waves broadens the applicability of features common to 2D turbulent flows to the context of surface wave phenomena which is prevalent in many systems.

Two-point closures and their applications: report on a workshop

2001 ◽  
Vol 436 ◽  
pp. 393-407 ◽  
Author(s):  
F. S. GODEFERD ◽  
C. CAMBON ◽  
J. F. SCOTT
Keyword(s):  
Turbulent Flows ◽  
Large Scale ◽  
Expert Knowledge ◽  
Local Equilibrium ◽  
Three Dimensional ◽  
Cascade Process ◽  
Satisfactory Description ◽  
Analysis And Design ◽  
Global Challenge ◽  
Wide Range

This international scientific workshop was organized in Lyon, France, from 10 to 12 May 2000. Its focus was ‘Two-point closures and their applications’, with the understanding that the analysis and design of such models requires expert knowledge coming from a wide range of areas in turbulence research, e.g. experiments, numerical simulations, asymptotic models, etc.In the global challenge of turbulence modelling, two-point closures prove useful in many ways. Two-point correlations and spectra are useful measures of the distortion of the eddy structure of turbulence by stratification, large-scale strains, rotation, etc. In some cases, e.g. near boundaries, spectra can be drastically changed. In addition to the accurate characterization of turbulence, the explicit computation of two-point correlations or spectra shows how the internal dynamics of the various scales of motion are affected by such distortion, especially the cascade process on which the production/dissipation relationship depends. Distortion can be the cause of large departures from isotropic homogeneous turbulence, pulling turbulent flows far away from the local equilibrium that is often assumed. A rather weak departure can allow the use of linearized theories such as rapid distortion theory, for the applicability of which rational bounds may be estimated by comparisons with weakly nonlinear calculations. A different approach is necessary when dealing with larger departures, for instance due to growth of instabilities. In that case new physical or similarity arguments have to be employed to obtain a satisfactory description of the modification to the cascade process, which can even undergo reversal in the limit when three-dimensional turbulence becomes two-dimensional. Of course, significant changes in spectra have direct implications for one-point measures of turbulence – which can be explicitly derived by integration of two-point correlations – used in most industrial closure schemes. Such one-point models consequently need to be adapted when turbulence is strongly affected by distortion.

The Disquisition of the Three-Dimensional Optimize Validate System of Oil-Immersed Pump Lectotype

2012 ◽  
Vol 157-158 ◽  
pp. 827-832
Author(s):  
Qiang Li ◽  
Jian Zhong Li
Keyword(s):  
Expert System ◽  
Software Design ◽  
Intelligent System ◽  
Three Dimensional ◽  
Oil Field ◽  
Synthetic Approach ◽  
Systematic Analysis ◽  
Analysis And Design ◽  
Engineering Control ◽  
Key Points

The applicability and accuracy of whole set oil-immersed pump lectotype are the key points to improve the recovery ratio of oil field and to conserve energy. This paper have conceived the construction and implementation of the expert system of whole set oil-immersed pump lectotype and discussed in several aspects: such as systematic analysis and design, the construction of engineering control platform, the development of plug-in software, the construction of intelligent system and the execution of software design and so on. It has integrated the synthetic approach with expert System of Whole Set Oil-immersed Pump lectotype.

scholarly journals Vortex identification in turbulent flows past plates using the Lagrangian method

2019 ◽  
Vol 97 (8) ◽  
pp. 895-910
Author(s):  
Bashar Attiya ◽  
I-Han Liu ◽  
Muhannad Altimemy ◽  
Cosan Daskiran ◽  
Alparslan Oztekin
Keyword(s):  
Turbulent Flow ◽  
Turbulent Flows ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Spatial Location ◽  
High Fidelity ◽  
Vortex Identification ◽  
Finite Time Lyapunov Exponent ◽  
Large Eddy ◽  
Spatial And Temporal Characteristics

Vortex identifications in turbulent flows past arrays of tandem plates are performed by employing the velocity field obtained by high-fidelity large eddy simulations. Lagrangian coherent structures (LCSs) are extracted to examine the evolution and the nonlinear interaction of vortices and to characterize the spatial and temporal characteristics of the flow. LCSs’ identification method is based on the finite-time Lyapunov exponent (FTLE), which is evaluated using the instantaneous velocity data. The simulations are performed in three-dimensional geometries to understand the physics of fluid motion and the vortex dynamics in the vicinity of plates and surfaces at Reynolds number of 50 000. The instantaneous vorticity fields, Eulerian Q-criterion, and LCSs are presented to interpret and understand complex turbulent flow structures. The three-dimensional FTLE fields provide valuable information about the vortex generation, spatial location, evolution, shedding, decaying, and dissipation of vortices. It is demonstrated here that FTLE can be used together with Eulerian vortex identifiers to characterize the turbulent flow field effectively.

Three-dimensional Lagrangian transport phenomena in unsteady laminar flows driven by a rotating sphere

2013 ◽  
Vol 25 (9) ◽  
pp. 093602 ◽  
Author(s):  
N. R. Moharana ◽  
M. F. M. Speetjens ◽  
R. R. Trieling ◽  
H. J. H. Clercx
Keyword(s):  
Transport Phenomena ◽  
Three Dimensional ◽  
Laminar Flows ◽  
Lagrangian Transport ◽  
Rotating Sphere

scholarly journals Evaluating variability in coseismic slips of paleoearthquakes from an incomplete slip history: an example from displaced terrace flights across the Kamishiro fault, central Japan

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Naoya Takahashi ◽  
Shinji Toda
Keyword(s):  
Monte Carlo ◽  
Three Dimensional ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Reverse Fault ◽  
Central Japan ◽  
Systematic Analysis ◽  
Fluvial Terraces ◽  
Rupture Length ◽  
Slip History

AbstractExamining the regularity in slip over seismic cycles leads to an understanding of earthquake recurrence and provides the basis for probabilistic seismic hazard assessment. Systematic analysis of three-dimensional paleoseismic trenches and analysis of offset markers along faults reveal slip history. Flights of displaced terraces have also been used to study slips of paleoearthquakes when the number of earthquakes contributing to the observed displacement of a terrace is known. This study presents a Monte Carlo-based approach to estimating slip variability using displaced terraces when a detailed paleoseismic record is not available. First, we mapped fluvial terraces across the Kamishiro fault, which is an intra-plate reverse fault in central Japan, and systematically measured the cumulative dip slip of the mapped terraces. By combining these measurements with the age of the paleoearthquakes, we estimated the amount of dip slip for the penultimate event (PE) and antepenultimate event (APE) to be 1.6 and 3.4 m, respectively. The APE slip was nearly three times larger than the most recent event of 2014 (Mw 6.2): 1.2 m. This suggests that the rupture length of the APE was much longer than that of the 2014 event and the entire Kamishiro fault ruptured with adjacent faults during the APE. Thereafter, we performed the Monte Carlo simulations to explore the possible range of the coefficient of variation for slip per event (COVs). The simulation considered all the possible rupture histories in terms of the number of events and their slip amounts. The resulting COVs typically ranged between 0.3 and 0.54, indicating a large variation in the slip per event of the Kamishiro fault during the last few thousand years. To test the accuracy of our approach, we performed the same simulation to a fault whose slip per event was well constrained. The result showed that the error in the COVs estimate was less than 0.15 in 86% of realizations, which was comparable to the uncertainty in COVs derived from a paleoseismic trenching. Based on the accuracy test, we conclude that the Monte Carlo-based approach should help assess the regularity of earthquakes using an incomplete paleoseismic record.

scholarly journals Numerical Study of Three-Dimensional Surface Jets Emerging from a Fishway Entrance Slot

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1079
Author(s):  
Lena Mahl ◽  
Patrick Heneka ◽  
Martin Henning ◽  
Roman B. Weichert
Keyword(s):  
Boundary Conditions ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Three Dimensional ◽  
Free Water ◽  
Lateral Wall ◽  
Lateral Spreading ◽  
Propagation Length ◽  
Vertical Slot ◽  
Surface Jets

The efficiency of a fishway is determined by the ability of immigrating fish to follow its attraction flow (i.e., its jet) to locate and enter the fishway entrance. The hydraulic characteristics of fishway entrance jets can be simplified using findings from widely investigated surface jets produced by shaped nozzles. However, the effect of the different boundary conditions of fishway entrance jets (characterized by vertical entrance slots) compared to nozzle jets must be considered. We investigate the downstream propagation of attraction jets from the vertical slot of a fishway entrance into a quiescent tailrace, considering the following boundary conditions not considered for nozzle jets: (1) slot geometry, (2) turbulence characteristics of the approach flow to the slot, and (3) presence of a lateral wall downstream of the slot. We quantify the effect of these boundary conditions using three-dimensional hydrodynamic-numeric flow simulations with DES and RANS turbulence models and a volume-of-fluid method (VoF) to simulate the free water surface. In addition, we compare jet propagation with existing analytical methods for describing jet propagations from nozzles. We show that a turbulent and inhomogeneous approach flow towards a vertical slot reduces the propagation length of the slot jet in the tailrace due to increased lateral spreading compared to that of a jet produced by a shaped nozzle. An additional lateral wall in the tailrace reduces lateral spreading and significantly increases the propagation length. For highly turbulent flows at fishway entrances, the RANS model tends to overestimate the jet propagation compared to the transient DES model.

The Analysis and Design of a Fire Engine Safety Cab Using Finite Element Methods

1977 ◽  
Vol 191 (1) ◽  
pp. 187-193 ◽  
Author(s):  
J. C. Miles ◽  
G. A. Wardill
Keyword(s):  
Finite Element ◽  
Computer Program ◽  
Three Dimensional ◽  
Analysis And Design ◽  
Vehicle Structure ◽  
Collapse Analysis ◽  
Incremental Formulation ◽  
Analysis Computer ◽  
Fire Engine ◽  
Analysis Computer Program

A three dimensional structural collapse analysis computer program is described, and illustrated by reference to a safety vehicle structure analysed and designed using the program. The particular problems of large displacements and material non-linearity are accounted for, and a method of estimating the permanent set which results after impact is described. Based on an incremental formulation of the conventional finite-element method, the computer program is capable of tracing the complete load deflection characteristics of a structure up to and beyond the point of collapse.

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