Effects of Water Temperature on Clinging Flow of Rectangular Sharp-Crested Weir

2012 ◽  
Vol 212-213 ◽  
pp. 1151-1154
Author(s):  
Yan Jun Ji ◽  
Xin Zhang ◽  
Hai Feng Zhai ◽  
Dong Yang Ren ◽  
Ling Hua
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Numerical Model ◽  
Water Temperature ◽  
Discharge Capacity ◽  
Flow Rate ◽  
Two Dimensional ◽  
Effect Of Water ◽  
Low Head ◽  
Temperature Levels

Surface tension associated with temperature is usually considered non-negligible to affect discharge capacity of sharp-crested weir when head is low. In the study, a two-dimensional numerical model verified by experiments was applied to simulate the effect of water temperature on discharge capacity of clinging flow for a rectangular sharp-crested weir at low head levels. The results showed that with a same flow rate, differences in the elevation of free surface were minimal between different temperature levels despite a slightly higher elevation of free surface at lower water temperature. The head-discharge relationships were very similar for different temperature levels. This study concluded that the effect of water temperature on head-discharge relationships and the discharge capacity of clinging flow for a rectangular sharp-crested weir was negligible at low heads.

scholarly journals Nonlinear two-dimensional free surface solutions of flow exiting a pipe and impacting a wedge

2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Alex Doak ◽  
Jean-Marc Vanden-Broeck
Keyword(s):  
Surface Tension ◽  
Integral Equation ◽  
Free Surface ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Two Dimensional ◽  
Numerical Schemes ◽  
Additional Advantage ◽  
Infinite Wedge ◽  
Good Agreement

AbstractThis paper concerns the flow of fluid exiting a two-dimensional pipe and impacting an infinite wedge. Where the flow leaves the pipe there is a free surface between the fluid and a passive gas. The model is a generalisation of both plane bubbles and flow impacting a flat plate. In the absence of gravity and surface tension, an exact free streamline solution is derived. We also construct two numerical schemes to compute solutions with the inclusion of surface tension and gravity. The first method involves mapping the flow to the lower half-plane, where an integral equation concerning only boundary values is derived. This integral equation is solved numerically. The second method involves conformally mapping the flow domain onto a unit disc in the s-plane. The unknowns are then expressed as a power series in s. The series is truncated, and the coefficients are solved numerically. The boundary integral method has the additional advantage that it allows for solutions with waves in the far-field, as discussed later. Good agreement between the two numerical methods and the exact free streamline solution provides a check on the numerical schemes.

Simulation and Optimization of Homogeneous Decomposition of Sulfur Trioxide Gas on a Catalytic Surface

2005 ◽  
Author(s):  
Kiran K. Muramalla ◽  
Yitung Chen ◽  
Anthony E. Hechanova
Keyword(s):  
Heat Exchanger ◽  
Numerical Model ◽  
Surface Temperature ◽  
Flow Rate ◽  
Sulfur Trioxide ◽  
Tube Length ◽  
Two Dimensional ◽  
Wall Surface ◽  
Wall Surface Temperature ◽  
Homogeneous Decomposition

This paper deals with the development of a two-dimensional numerical model to predict the wall-catalyzed homogeneous decomposition of sulfur trioxide in a tubular component geometry for the production of hydrogen by the sulfur-iodine thermochemical water splitting cycle, a candidate cycle in the U.S. Department of Energy Nuclear Hydrogen Initiative. The reacting fluid is a mixture of sulfur trioxide gas and water vapor inside the tubes of a heat exchanger. The heat exchanger is made of Incoloy alloy 800H with ALFA-4 coated on the inner walls which acts as a catalyst. Decomposition of sulfur trioxide depends on many different parameters such as wall surface temperature, mole flow rate of the reacting mixture, diameter of the reactor tube, length of the reactor tube, operating pressure and inlet temperature of the reacting mixture. The effects of wall surface temperature, diameter of the reactor tube and mole flow rate on the decomposition of sulfur trioxide were investigated using a two-dimensional numerical model using Computational Fluid Dynamics (CFD) techniques. The preprocessor GAMBIT was used to create a computational mesh and the CFD software package FLUENT 6.2.16 [1] which is based on finite volume methods was used to simulate the problem. Both FLUENT 6.2.16 and Tecplot 10.0 are used to post process the problem.

A Numerical Model for the Evaporation of a Nanoliter Droplet on a Solid, Heated Substrate

2007 ◽  
Author(s):  
Rajneesh Bhardwaj ◽  
Daniel Attinger
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Evaporation Time ◽  
Flat Substrate ◽  
Lagrangian Framework ◽  
Thermodynamic Conditions ◽  
Isothermal Case ◽  
Evaporative Flux ◽  
Temperature Levels ◽  
Made In

A finite-element numerical model is developed to study the evaporation of a sessile nanoliter droplet on a flat substrate in the isothermal and non-isothermal case. All equations are expressed in a Lagrangian framework, which provides accurate modeling of the free surface motion and the associated Laplace stresses. The evaporative flux at the free surface is defined as a function of the drop geometry and thermodynamic conditions. The boundary conditions at free surface are the mass and energy jump conditions. Results for fluid dynamics, evaporation time and evaporative flux are described for substrate temperature levels of 27°C (ambient), 82°C and 122°C. Comparisons with experiments are made, in terms of the evolution of volume, wetting angle and wetted radius.

scholarly journals Numerical modeling of fluid resonance in narrow gaps of fixed rectangular structures

2019 ◽  
Vol 11 (8) ◽  
pp. 168781401987230
Author(s):  
Ming-ming Liu ◽  
Rui-jia Jin ◽  
Zhen-dong Cui
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Stokes Equations ◽  
Theoretical Data ◽  
Numerical Results ◽  
Two Dimensional ◽  
Arbitrary Lagrangian Eulerian ◽  
Fluid Resonance ◽  
Resonance Wave ◽  
Narrow Gaps

A two-dimensional numerical model is developed to investigate the phenomenon of resonance in narrow gaps. Instead of using commonly used Volume of Fluid method to capture the free surface which is sometimes difficult to capture the geometric properties of the geometrically complicated interface, the free surface is traced by using Arbitrary Lagrangian–Eulerian method. The numerical model is based on the two-dimensional Reynolds-Averaged Navier–Stokes equations. The numerical model is validated against wave propagation in wave flume. Comparisons between the numerical results and available theoretical data show satisfactory agreements. Fluid resonance in narrow gaps of fixed rectangular structures are simulated. Numerical results show that resonance wave height and wave frequency for rectangle boxes with sphenoid corners is larger than for rectangle boxes.

On the Disturbance of a Thin Layer of Liquid by a Moving Obstruction

1990 ◽  
Vol 57 (4) ◽  
pp. 1066-1072
Author(s):  
Roger F. Gans ◽  
Chung-Hai Wang
Keyword(s):  
Surface Tension ◽  
Reynolds Number ◽  
Free Surface ◽  
Thin Layer ◽  
Viscous Flow ◽  
Length Scale ◽  
Two Dimensional ◽  
Thin Liquid Layer ◽  
Horizontal Length ◽  
Small Ratio

We calculate the free surface shapes upstream and downstream of an obstacle obstructing a thin liquid layer on a moving surface, taking into account gravity and surface tension. We assume low Reynolds number viscous flow, a two-dimensional layer, and small ratio of vertical to horizontal length scale. The upstream and downstream shapes are very different. The upstream liquid piles up against the obstacle to provide an overpressure sufficient to drive the Poiseuille component of the lubrication flow under the obstacle. The downstream liquid is disturbed only by surface tension.

scholarly journals On periodic Stokesian Hele-Shaw flows with surface tension

2008 ◽  
Vol 19 (6) ◽  
pp. 717-734 ◽  
Author(s):  
J. ESCHER ◽  
B.-V. MATIOC
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Incompressible Fluid ◽  
Classical Solution ◽  
Small Perturbation ◽  
Darcy’S Law ◽  
Viscous Incompressible Fluid ◽  
Darcy's Law ◽  
Two Dimensional ◽  
Unique Classical Solution

In this paper we consider a 2π-periodic and two-dimensional Hele-Shaw flow describing the motion of a viscous, incompressible fluid. The free surface is moving under the influence of surface tension and gravity. The motion of the fluid is modelled using a modified version of Darcy's law for Stokesian fluids. The bottom of the cell is assumed to be impermeable. We prove the existence of a unique classical solution for a domain which is a small perturbation of a cylinder. Moreover, we identify the equilibria of the flow and study their stability.

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