On flow simplification occurring in viscous three-dimensional water flows with constant non-vanishing vorticity

2021 ◽  
pp. 107690
Author(s):  
Calin I. Martin
Keyword(s):  
Three Dimensional ◽  
Water Flows

Quasi-two-layer finite-volume scheme for modelling shallow water flows over an arbitrary bed in the presence of external force. II. Algorithm applications and numerical results

2014 ◽  
Vol 29 (3) ◽  
Author(s):  
Kirill V. Karelsky ◽  
Arakel S. Petrosyan ◽  
Alexander G. Slavin
Keyword(s):  
Shallow Water ◽  
Finite Volume ◽  
External Force ◽  
Large Scale ◽  
Lower Layer ◽  
Three Dimensional ◽  
Finite Volume Scheme ◽  
Water Flows ◽  
Shallow Water Flows ◽  
Scale Motion

AbstractA finite-volume numerical method for studying shallow water flows over an arbitrary bed profile in the presence of external force has been proposed in [33]. This method uses the quasi-two-layer model of hydrodynamic flows over a stepwise boundary with advanced consideration of the flow features near the step. A distinctive feature of the suggested model is a separation of the studied flow into two layers in calculating the flow quantities near each step, and improving by this means the approximation of depth-averaged solutions of the initial three-dimensional Euler equations. We are solving the shallow-water equations for one layer, introducing the fictitious lower layer only as an auxiliary structure in setting up the appropriate Riemann problems for the upper layer. Besides, the quasi-two-layer approach leads to the appearance of additional terms in the one-layer finite-difference representation of balance equations. Numerical simulations are performed based on the proposed in [33] algorithm of various physical phenomena, such as breakdown of the rectangular fluid column over an inclined plane, large-scale motion of fluid in the gravity field in the presence of Coriolis force over amounted obstacle on the underlying surface. Computations are made for the two-dimensional dam-break problem on a slope precisely conform to laboratory experiments. The interaction of the Tsunami wave with the shore line including an obstacle has been simulated to demonstrate the efficiency of the developed algorithm in domains, including partly flooded and dry regions.

scholarly journals In vivo intraoral waterflow quantification reveals hidden mechanisms of suction feeding in fish

2021 ◽  
Author(s):  
Pauline Provini ◽  
Alexandre Brunet ◽  
Andréa Filippo ◽  
Sam Van Wassenbergh
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
New Technique ◽  
Fish Feed ◽  
Suction Feeding ◽  
Apparent Paradox ◽  
X Ray ◽  
Water Flows ◽  
Food Transport

Virtually all fish rely on flows of water to transport food to the back of their pharynx. While external flows that draw food into the mouth are well described, how intra-oral water flows manage to deposit food at the esophagus entrance remains unknown. In theory, the posteriorly moving water must, at some point, curve laterally and/or ventrally to exit through the gill slits. Such flows would eventually carry food away from the esophagus instead of towards it. This apparent paradox calls for a filtration mechanism to deviate food from the suction-feeding streamlines. To study this gap in our fundamental understanding of how fish feed, we developed and applied a new technique to quantify three-dimensional patterns of intra-oral water flows in vivo. We combined stereoscopic high-speed x-ray videos to quantify skeletal motion (XROMM) with 3D x-ray particle tracking (XPT) of approximately neutrally buoyant spheres of 1.4 mm in diameter. We showed, for carp (Cyprinus carpio) and tilapia (Oreochromis niloticus), that water tracers displayed higher curvatures than food tracers, indicating an inertia-driven filtration. In addition, tilapia also exhibited a 'central jet' flow pattern, which aids in quickly carrying food to the pharyngeal jaw region. When the food was trapped at the branchial basket, it was resuspended and carried more centrally by periodical bidirectional waterflows, synchronized with head-bone motions. By providing a complete picture of the suction-feeding process and revealing fundamental differences in food transport mechanisms among species, this new technique opens a new area of investigation to fully understand how most aquatic vertebrates feed.

A numerical model for three-dimensional shallow water flows with sharp gradients over mobile topography

2017 ◽  
Vol 154 ◽  
pp. 1-11
Author(s):  
Xin Liu ◽  
Abdolmajid Mohammadian ◽  
Julio Ángel Infante Sedano
Keyword(s):  
Numerical Model ◽  
Shallow Water ◽  
Three Dimensional ◽  
Water Flows ◽  
Shallow Water Flows

scholarly journals Vortex Valve – Principle, Design and Application

2018 ◽  
Vol 11 (2) ◽  
pp. 9
Author(s):  
Karel Adámek ◽  
Jan Kolář ◽  
Pavel Peukert
Keyword(s):  
Numerical Simulation ◽  
Flow Characteristic ◽  
Three Dimensional ◽  
Flow Fields ◽  
Water Levels ◽  
Three Dimensional Flow ◽  
One Dimensional ◽  
Transitional Area ◽  
Water Flows ◽  
High Flows

The paper contains the overview of so-called vortex valve, used as outlet device on retention reservoirs for retention of rainstorms and later slow outflow into drainage etc. Simple one-dimensional equations are well known, but for complex three-dimensional flow fields inside the valve the method of flow numerical simulation is used. Particular paragraphs contain the theory of flow fields inside, explanation of branched flow characteristic, separated by transitional area, basics of designing and influence of both inlet/outlet opening sizes on the form of characteristic, valve adaptation for high flows at low water levels etc. Results are used for designing of new model series of valves for various water flows and levels.

scholarly journals Simulation of the Thermal Hydraulic Processes in the Horizontal Steam Generator with the Use of the Different Interfacial Friction Correlations

2011 ◽  
Vol 2011 ◽  
pp. 1-9
Author(s):  
Vladimir Melikhov ◽  
Oleg Melikhov ◽  
Yury Parfenov ◽  
Alexey Nerovnov
Keyword(s):  
Steam Generator ◽  
Three Dimensional ◽  
Test Facility ◽  
Interfacial Friction ◽  
Water Mixture ◽  
Pressurized Water ◽  
Design And Optimization ◽  
Water Flows ◽  
Horizontal Steam Generator ◽  
Water Reactors

The horizontal steam generator (SG) is one of specific features of Russian-type pressurized water reactors (VVERs). The main advantages of horizontal steam generator are connected with low steam loads on evaporation surface, simple separation scheme and high circulation ratio. The complex three-dimensional steam-water flows in the steam generator vessel influence significantly the processes of the steam separation, distribution, and deposition of the soluble and nonsoluble impurities and determine the efficiency and reliability of the steam generator operation. The 3D code for simulation of the three-dimensional steam-water flows in the steam generator could be effective tool for design and optimization of the horizontal steam generator. The results of the code calculations are determined mainly by the set of the correlations describing interaction of the steam-water mixture with the inner constructions of the SG and interfacial friction. The results obtained by 3D code STEG with the usage of the different interfacial friction correlations are presented and discussed in the paper. These results are compared with the experimental ones obtained at the experimental test facility PGV-1500 constructed for investigation of the processes in the horizontal steam generator.

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