Lock-Exchange Flows in Non-Rectangular Cross-Section Channels

2004 ◽  
Vol 126 (2) ◽  
pp. 290-292 ◽  
Author(s):  
Luis Thomas and ◽  
Beatriz Marino
Keyword(s):  
Analytical Model ◽  
Cross Section ◽  
Laboratory Experiments ◽  
Rectangular Cross Section ◽  
Hydraulic Engineering ◽  
Stratified Flows ◽  
Straight Channel ◽  
Simple Analytical Model ◽  
Engineering Structures ◽  
Exchange Flows

Lock-exchange flows driven by density differences in non-rectangular cross-section channels are investigated in situations that resemble estuaries, navigation canals and hydraulic engineering structures. A simple analytical model considering stratified flows suggests practical relationships corroborated by results of laboratory experiments carried out in a straight channel of triangular cross-section.

Pseudo-analytical model for calculation of flat circular inductors with rectangular cross-section

2018 ◽  
Vol 78 ◽  
pp. 46-53 ◽  
Author(s):  
Pedro Luis Ferrer Penalver ◽  
Carmen Leticia Crespillo Torriente ◽  
Edmundo da Silva Braga ◽  
Marco Antonio Robert Alves ◽  
Paulo Henrique Roesler ◽  
...  
Keyword(s):  
Analytical Model ◽  
Cross Section ◽  
Rectangular Cross Section

Symmetric Holmboe instabilities in a laboratory exchange flow

2009 ◽  
Vol 636 ◽  
pp. 137-153 ◽  
Author(s):  
EDMUND W. TEDFORD ◽  
R. PIETERS ◽  
G. A. LAWRENCE
Keyword(s):  
Cross Section ◽  
Laboratory Experiments ◽  
Rectangular Cross Section ◽  
Flow Direction ◽  
Phase Speed ◽  
Exchange Flow ◽  
Subcritical Region ◽  
Average Wavelength

Laboratory experiments have been conducted that test the predictions of Holmboe (Geofys. Publ., vol. 24, 1962, pp. 67–112). Symmetric Holmboe instabilities are observed during steady, maximal two-layer exchange flow in a long laboratory channel of rectangular cross-section. Internal hydraulic controls at each end of the channel isolate the subcritical region within the channel from disturbances in the reservoirs. Inside the channel, the instabilities form cusp-like waves that propagate in both directions. The phase speed of the instabilities is consistent with Holmboe's theory and increases along the length of the channel as a result of the gradual acceleration of each layer. This acceleration causes the wavelength of any given instability to increase in the flow direction until it is approximately twice the most amplified wavelength. At this point new waves develop with the result that the average wavelength is almost constant along the length of the channel.

Joining by Forming of Tubes to Sheets with Counterbored Holes

2018 ◽  
Vol 767 ◽  
pp. 421-428 ◽  
Author(s):  
Luis M. Alves ◽  
Rafael M. Afonso ◽  
Carlos M.A. Silva ◽  
Paulo A.F. Martins
Keyword(s):  
Analytical Model ◽  
Cross Section ◽  
Room Temperature ◽  
Tube Wall ◽  
Rectangular Cross Section ◽  
Dissimilar Materials ◽  
Forming Process ◽  
Element Analysis ◽  
Joining By Forming ◽  
Tube Wall Thickness

This paper presents a new joining by forming process for connecting tubes to sheets. The process consists of forming an annular flange with rectangular cross section by partial sheet-bulk of the tube wall thickness and performing the mechanical interlock by upsetting the free tube end against a flat-bottomed (counterbored) sheet hole. The presentation identifies the variables and the workability limits of the process and includes an analytical model to assist readers in the design of the new joints. The new proposed joining by forming process and the corresponding analytical model are validated by experimentation and numerical simulation using finite element analysis. The process allows connecting tubes to sheets made from dissimilar materials at room temperature, avoids the utilization of addition materials or adhesives and produces joints that are easy to disassembly at the end of live, allowing recyclability of the tubes and sheets.

FE-PML MODELING OF 3D SCATTERING OF TRANSIENT ELASTIC WAVES IN CRACKED PLATE WITH RECTANGULAR CROSS SECTION

2010 ◽  
Vol 10 (05) ◽  
pp. 1123-1139 ◽  
Author(s):  
ABDEL-RAHMAN MAHMOUD ◽  
NIPON RATTANAWANGCHAROEN ◽  
YUNHUA LUO ◽  
QUAN WANG
Keyword(s):  
Nondestructive Evaluation ◽  
Cross Section ◽  
Elastic Waves ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Infinite Plate ◽  
Mean Square ◽  
Engineering Structures ◽  
Practical Applications ◽  
Proposed Model

This paper proposes a finite-element (FE) and perfectly matched layer (PML)modeling of three-dimensional (3D) scattering of transient elastic waves in a cracked infinite plate with rectangular cross-section. The FE predictions are validated against 3D semi-analytical literature results. The effects of PML parameters on a root-mean-square error estimate are measured against the reference FE predictions computed using extended meshes. The proposed model is shown, through the numerical examples, to offer huge saving in real run-time at a slight degradation in accuracy. Practical applications indicate its potential in modeling elastic-wave-based nondestructive evaluation of engineering structures.

Front Condition for Gravity Currents in Channels of Nonrectangular Symmetric Cross-Section Shapes

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
B. M. Marino ◽  
L. P. Thomas
Keyword(s):  
Froude Number ◽  
Cross Section ◽  
Laboratory Experiments ◽  
Rectangular Cross Section ◽  
Theoretical Models ◽  
Gravity Currents ◽  
Cross Section Shape ◽  
Section Shape ◽  
Front Condition ◽  
Upper Boundary

We study the variation of the Froude number at the front of gravity currents developed in uniform channels whose cross-section shape depends on a parameter usually used in many numerical and theoretical models. The thickness and front velocity of the dense currents running on the bottom are greater for all the cases studied, resulting in a Froude number greater than that corresponding to the rectangular cross-section shape. The light currents developing along the upper boundary show the opposite trend. It is found that the results are not related to the depth and width of the channel. The relationships obtained agree with the results of laboratory experiments in which open and closed channels of different cross-section shapes are used.

The effect of aspect ratio on longitudinal diffusivity in rectangular channels

1982 ◽  
Vol 120 ◽  
pp. 347-358 ◽  
Author(s):  
P. C. Chatwin ◽  
Paul J. Sullivan
Keyword(s):  
Laminar Flow ◽  
Aspect Ratio ◽  
Cross Section ◽  
Laboratory Experiments ◽  
Rectangular Cross Section ◽  
Independent Method ◽  
Surprising Result ◽  
Large Aspect Ratio ◽  
Rectangular Channels ◽  
Side Walls

In a recent paper Doshi, Daiya & Gill (1978) showed that the value of Taylor's longitudinal diffusivity D for laminar flow in a channel of rectangular cross-section of breadth u and height b is about 8D0, for large values of the aspect ratio a/b, where Do is the value of the longitudinal diffusivity obtained by ignoring all variation across the channel. This superficially surprising result is confirmed by an independent method, and is shown to be caused by the boundary layers on the side walls of the channel. The primary purpose of the paper, however, is to consider the value of D in turbulent flow in a flat-bottomed channel of large aspect ratio, for which arguments based on physics are adduced in support of the formula D≈[1 + B][1 - λ(b/u)], where B and λ are positive constants independent of b. It is shown that this result is consistent with laboratory experiments by Fischer (1966). The paper concludes with a discussion of the practical effects of aspect ratio on longitudinal dispersion in channels whose cross-section is approximately rectangular.

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