scholarly journals Introducing the T-shaped weir: a new nonlinear weir

2021 ◽  
Author(s):  
Behzad Noroozi ◽  
Jalal Bazargan ◽  
Akbar Safarzadeh
Keyword(s):  
Discharge Coefficient ◽  
Vertical Wall ◽  
Hydraulic Performance ◽  
Height Ratio ◽  
Maximum Increase ◽  
Labyrinth Weir ◽  
Numerical Tests ◽  
Vertical Walls ◽  
Piano Key Weir ◽  
3D Software

Abstract In the present study, a new nonlinear weir called the T-Shaped Weir (TSW), which is a combination of the Labyrinth Weir (LW) and the Piano Key Weir (PKW), was introduced, and its hydraulic performance was compared with the PKW. Based on the presence of the vertical walls at the inlet key, outlet key, or both keys, the TSW weirs were classified as type A, B, and C weirs, respectively. The flow pattern of different TSW cases was analyzed, and the discharge coefficient curves were provided. Furthermore, to accurately study the hydrodynamics of the tested weirs, the 3D numerical simulations were performed using the FLOW-3D software. The results showed that inserting a vertical wall at the upstream of the outlet keys (C-TSW type) has a negligible effect on the hydraulic performance of the PKW. A maximum increase of 16% occurred in the discharge coefficient of the B-TSW in comparison to the PKW, and up to a head to height ratio (Ht/p) of 0.45, effect of the vertical wall on increasing the performance of the B-TSW was maintained. Based on the experimental and numerical tests, the optimal height ratio of the vertical wall (Pd/P) in B-TSW with highest discharge capacity was determined equal to 0.4.

scholarly journals Parametric CFD Thermal Performance Analysis of Full, Medium, Half and Short Length Dimple Solar Air Tube

2021 ◽  
Vol 13 (11) ◽  
pp. 6462
Author(s):  
Mir Waqas Alam ◽  
Basma Souayeh
Keyword(s):  
Thermal Performance ◽  
Energy Transport ◽  
Hydraulic Performance ◽  
Short Length ◽  
Working Fluid ◽  
Solar Air Heater ◽  
Hydraulic Characteristics ◽  
Height Ratio ◽  
Pitch Ratio ◽  
Full Medium

In the present decade, research regarding solar thermal air heaters (SAHs) has noticed a continuous progression in thermo-hydraulic performance augmentation approaches. There now exists a wide variety of thermo-hydraulic performance augmentation approaches and researchers have designated various structures. Nevertheless, there seems to be no generalization to any of the approaches employed. The present numerical investigation reports on the thermo-hydraulic characteristics and thermal performance for flow through a varied length (full, medium, half, and short length) dimple solar air heater (SAH) tube. The study highlights recent developments on enhanced tubes to augment heat transfer in SAH. The influence of different length ratio, dimple height ratio (H), and pitch ratio (s) on thermo-hydraulic characteristics have been investigated in the Reynolds number (Re) range from 5000 to 25,000. Air is used as the working fluid. The commercial software ANSYS Fluent is used for simulation. The shear stress transport (SST) model is used as the turbulence model. Thermal energy transport coefficient is increased in the full-length dimple tube (FLDT), compared to the medium-length dimple tube (MLDT), half-length dimple tube (HLDT) and short-length dimple tube (SLDT). Similarly, the pitch ratio (s) has more influence on Nusselt number (Nu) compared to the dimple height ratio (H). The friction factor decreases with an increase in pitch ratio. Nu increases and f decreases with increasing Re for all combinations of H and s. Low s and higher H yields high enhancement of HT and PD. Integration of artificial roughness on the tube increases the values of Nu and f by 5.12 times and 77.23 times for H = 0.07, s = 1.0 at Re value of 5000 and 25,000, respectively, in regard to the plain tube. For all the tested cases, the thermo-hydraulic performances (η) are greater than unity.

Discharge coefficient of a rectangular labyrinth weir

2013 ◽  
Vol 166 (8) ◽  
pp. 443-451 ◽  
Author(s):  
Abdorreza Kabiri-Samani ◽  
Amir Javaheri ◽  
Seyed Mahmood Borghei
Keyword(s):  
Discharge Coefficient ◽  
Labyrinth Weir

scholarly journals Slit-type Breakwater; Box-type Wave Absorber

1976 ◽  
Vol 1 (15) ◽  
pp. 154 ◽  
Author(s):  
Shoshichiro Nagai ◽  
Shohachi Kakuno
Keyword(s):  
Cross Section ◽  
Water Depth ◽  
Vertical Wall ◽  
Bottom Wall ◽  
Front Wall ◽  
Type Wave ◽  
Composite Type ◽  
New Type ◽  
Vertical Walls ◽  
Horizontal Bottom

A box-type wave absorber, which is composed of a perforated vertical front-wall and a perforated, horizontal bottom-wall, has been proved by a number of experiments to show lower coefficients of reflection and more distinguished reduction of wave pressures than the perforated vertical- wall breakwater. A breakwater of composite-type, which is 1500 m long and to be built at a water depth of 10 to 11 m below the Datum Line in the Port of Osaka, is being designed to set this new type of wave absorber in the concrete caissons of the vertical-walls which is named "a slit-type breakwater". The typical cross-section of the breakwater and the advantages of the slit-type breakwater are presented herein.

The Effect of the Top Wall Temperature on the Laminar Natural Convection in Rectangular Cavities With Different Aspect Ratios

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Wenjiang Wu ◽  
Chan Y. Ching
Keyword(s):  
Natural Convection ◽  
Aspect Ratio ◽  
Wall Temperature ◽  
Vertical Wall ◽  
Flow Region ◽  
Temperature Profiles ◽  
Aspect Ratios ◽  
Vertical Walls ◽  
C And N ◽  
Laminar Natural Convection

The effect of the top wall temperature on the laminar natural convection in air-filled rectangular cavities driven by a temperature difference across the vertical walls was investigated for three different aspect ratios of 0.5, 1.0, and 2.0. The temperature distributions along the heated vertical wall were measured, and the flow patterns in the cavities were visualized. The experiments were performed for a global Grashof number of approximately 1.8×108 and nondimensional top wall temperatures from 0.52 (insulated) to 1.42. As the top wall was heated, the flow separated from the top wall with an undulating flow region in the corner of the cavity, which resulted in a nonuniformity in the temperature profiles in this region. The location and extent of the undulation in the flow are primarily determined by the top wall temperature and nearly independent of the aspect ratio of the cavity. The local Nusselt number was correlated with the local Rayleigh number for all three cavities in the form of Nu=C⋅Ran, but the values of the constants C and n changed with the aspect ratio.

Application of Gaussian Process Regression Model to Predict Discharge Coefficient of Gated Piano Key Weir

2019 ◽  
Vol 33 (11) ◽  
pp. 3929-3947 ◽  
Author(s):  
Masood Akbari ◽  
Farzin Salmasi ◽  
Hadi Arvanaghi ◽  
Masoud Karbasi ◽  
Davood Farsadizadeh
Keyword(s):  
Regression Model ◽  
Gaussian Process ◽  
Discharge Coefficient ◽  
Gaussian Process Regression ◽  
Piano Key Weir

scholarly journals A new solution approach to the Serre equations

2020 ◽  
Author(s):  
T S Jang
Keyword(s):  
Solitary Wave ◽  
Vertical Wall ◽  
High Amplitude ◽  
Solution Procedure ◽  
Linear Wave ◽  
Linear Interaction ◽  
Solution Approach ◽  
Non Linear ◽  
Vertical Walls ◽  
Wave Phenomena

Abstract This paper concerns constructing a semi-analytic solution procedure for integrating the fully non-linear Serre equations (or 1D Green–Naghdi equations for constant water depth). The validity of the solution procedure is checked by investigating a moving solitary wave for which the analytical solution is known. The semi-analytic procedure constructed in this study is confirmed to be good at observing non-linear wave phenomena of the collision of a sufficiently high-amplitude solitary wave with a vertical wall. The simulated results are in a good agreement with data of other authors. Further, the procedure simulates the non-linear interaction of four solitary waves, which enables us to investigate the repeated reflection of a single solitary wave between two vertical walls.

NUMERICAL STUDY OF LAMINAR CONVECTION AND THERMOSOLUTAL CONVECTION IN A TWO-DIMENSIONAL TRAPEZOIDAL CAVITY

1994 ◽  
Vol 18 (3) ◽  
pp. 207-224 ◽  
Author(s):  
M. Lacroix
Keyword(s):  
Schmidt Number ◽  
Numerical Study ◽  
Temperature Gradients ◽  
Thermosolutal Convection ◽  
Governing Equations ◽  
Concentration Gradients ◽  
Height Ratio ◽  
Vertical Walls ◽  
Laminar Convection ◽  
Rayleigh Numbers

Heat transfer driven by temperature gradients and simultaneous temperature and concentration gradients has been studied numerically for horizontal prismatic cavities of trapezoidal section having a hot horizontal base, a cool inclined top and insulated vertical walls. Results are presented for a cavity with width-to-mean height ratio of 4, thermal and concentration Rayleigh numbers up to 106 and 5.105 respectively, and top surface inclinations from 0 to 15 deg to the horizontal. The Prandtl and the Schmidt number used are 0.71 and 0.6 respectively. The governing equations are expressed in terms of stream function and vorticity and body-fitted coordinates are used for mapping the sloping top wall. As the inclination of the top surface is increased, the Nusselt and Sherwood numbers decrease. The effect of opposing thermal and concentration gradients on the Nusselt and Sherwood numbers is however more important than the effect of the inclination of the top surface. Theoretical Nusselt and Sherwood numbers are compared with available experimental data.

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