Numerical Modeling of Flow Over a Rectangular Broad-Crested Weir with a Sloped Upstream Face

The objective of this study was to evaluate the effect of the upstream angle on flow over a trapezoidal broad-crested weir based on numerical simulations using the open-source toolbox OpenFOAM. Eight trapezoidal broad-crested weir configurations with different upstream face angles (θ = 10°, 15°, 22.5°, 30°, 45°, 60°, 75°, 90°) were investigated under free-flow conditions. The volume-of-fluid (VOF) method and two turbulence models (the standard k-ε model and the SST k-w model) were employed in the numerical simulations. The numerical results were compared with the experimental results obtained from published papers. The root mean square error (RMSE) and the mean absolute percent error (MAPE) were used to evaluate the accuracy of the numerical results. The statistical results show that RMSE and MAPE values of the standard k-ε model are 0.35–0.67% and 0.50–1.48%, respectively; the RMSE and MAPE values of the SST k-w model are 0.25–0.66% and 0.55–1.41%, respectively. Additionally, the effects of the upstream face angle on the flow features, including the discharge coefficient and the flow separation zone, were also discussed in the present study.

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Numerical Research of Flows into Gullies with Different Outlet Locations

Water ◽

10.3390/w11040794 ◽

2019 ◽

Vol 11 (4) ◽

pp. 794 ◽

Cited By ~ 2

Author(s):

Rita F. Carvalho ◽

Pedro Lopes ◽

Jorge Leandro ◽

Luis M. David

Keyword(s):

Surface Runoff ◽

Discharge Coefficient ◽

Drainage System ◽

Flow Conditions ◽

Hydraulic Behavior ◽

Discharge Coefficients ◽

Wide Range ◽

Flow Features ◽

Numerical Research ◽

Estimation Of Uncertainty

Gullies are sewer inlets placed in pavements usually covered by bar grates. They are the most common linking-element used to drain a wide range of flows from surface runoff into the buried drainage system. Their hydraulic behavior and their overall hydraulic performance is dependent on the flow conditions, the gully dimension, geometry, and location of the outlet device. Herein a numerical research based on Volume Of Fluid ( V O F ) to detect the interface, and on the Shear Stress Transport S S T k - ω turbulence model was conducted to study the importance of the outlet location and characterize flows through them in drainage conditions. Results provided detailed information about flow features, discharge coefficients, and efficiencies for different outlet locations. The authors identified three different regimes, R 1 , R 2 , and R 3 , and concluded that the outlet location influences the velocity field along the gully, the discharge coefficient, and the drainage efficiency. This allows for the estimation of uncertainty and its variation for different outlet positions.

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An Assessment of Five Turbulence Models in Predicting Turbulent Separation

Volume 2, Parts A and B ◽

10.1115/ht-fed2004-56813 ◽

2004 ◽

Cited By ~ 1

Author(s):

Robert E. Spall ◽

Warren F. Phillips ◽

Nick Alley

Keyword(s):

Reynolds Number ◽

Shear Stress ◽

Mach Number ◽

Turbulence Models ◽

Streamwise Velocity ◽

Numerical Results ◽

Flow Conditions ◽

Turbulent Separation ◽

Controlled Flow ◽

Flow Case

Four different turbulence models were employed to predict the flow over a wall-mounted Glauert-Goldschmied body. The models evaluated include: 1) two-layer k–ε, 2) shear stress transport, 3) low-Reynolds number k–ω, 4) Spalart-Allmaras, and 5) v2−f. Calculations were performed for both an uncontrolled case, and a controlled-flow case which used steady suction through a slot located at the 65% chord station. The flow conditions include a freestream Mach number of approximately 0.1, and a chord Reynolds number of just under 1 million. For each model, the numerical results over predicted the experimentally determined re-attachment length. An examination of streamwise velocity profiles at several stations downstream of the trailing edge revealed considerable variation in the predictions of the five turbulence models.

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Effect of Turbulence on Orifice Meter Performance

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.2920136 ◽

1994 ◽

Vol 116 (2) ◽

pp. 77-85 ◽

Cited By ~ 4

Author(s):

U. Karnik ◽

W. M. Jungowski ◽

K. K. Botros

Keyword(s):

Discharge Coefficient ◽

Tube Bundle ◽

Orifice Plate ◽

The Other ◽

Turbulent Velocity ◽

Atmospheric Conditions ◽

Flow Conditions ◽

The Mean ◽

Turbulent Velocity Field ◽

Good Flow

Mean and turbulent velocity profiles downstream of a 19-tube bundle are presented. Experiments have been carried out in 101.6-mm-dia piping configuration at prevalent atmospheric conditions with air as the fluid. The two cases considered are: one with the tube bundle placed in good flow conditions and the other with the tube bundle used as a sliding vane downstream of a single 90-deg elbow. In both cases, for various positions of the tube bundle with respect to an orifice plate, the discharge coefficient for the orifice plate has been compared to a baseline value. The results indicate that it is possible to correlate the deviations in the discharge coefficient to the mean and turbulent velocity field upstream of the orifice.

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Aerodynamic Performance Evaluation of 3D Aircraft Configurations by Turbulence Models

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-15014 ◽

2011 ◽

Author(s):

Einkeun Kwak ◽

Sang-il Park ◽

Namhun Lee ◽

Seungsoo Lee

Keyword(s):

Numerical Simulations ◽

Turbulent Flows ◽

Turbulence Model ◽

Turbulence Models ◽

Aerodynamic Characteristics ◽

Computational Results ◽

Flow Features ◽

Sst Turbulence Model ◽

Drag Prediction ◽

Aircraft Configurations

Numerical simulations of 3D aircraft configurations are performed in order to understand the effects that turbulence models have on the aerodynamic characteristics of an aircraft. An in-house CFD code that solves 3D RANS equations and 2-equation turbulence model equations is used for the study. The code applies Roe’s approximated Riemann solver and an AF-ADI scheme. Furthermore van Leer’s MUSCL extrapolation with van Albada’s limiter is adopted. Various versions of Menter’s k-omega SST turbulence models as well as Coakley’s q-omega model are incorporated into the CFD code. Menter’s k-omega SST models include the standard model, the 2003 model, the model incorporating the vorticity source term, and the model containing controlled decay. Turbulent flows over a wing are simulated in order to validate the turbulence models contained in the CFD code. The results from these simulations are then compared to computational results of the 3rd AIAA CFD Drag Prediction Workshop. Moreover, numerical simulations of the DLR-F6 wing-body and wing-body-nacelle-pylon configurations are conducted and compared to computational results of the 2nd AIAA CFD Drag Prediction Workshop. Especially, the aerodynamic characteristics as well as flow features with respect to the turbulence models are scrutinized. The results obtained from each simulation incorporating Menter’s k-omega SST turbulence model variations are compared with one another.

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Using Ansys for Design and Numerical Study of a Specific Fixed Wing UAV

Materiale Plastice ◽

10.37358/mp.18.4.5095 ◽

2018 ◽

Vol 55 (4) ◽

pp. 652-657 ◽

Cited By ~ 1

Author(s):

Gabriel Murariu ◽

Razvan Adrian Mahu ◽

Adrian Gabriel Murariu ◽

Mihai Daniel Dragu ◽

Lucian P. Georgescu ◽

...

Keyword(s):

Numerical Simulations ◽

Unmanned Aerial Vehicle ◽

Numerical Study ◽

Flight Time ◽

Cluster System ◽

Numerical Results ◽

Operational Performance ◽

Gliding Flight ◽

Aerial Vehicle ◽

Constant Altitude

This article presents the design of a specific unmanned aerial vehicle UAV prototype own building. Our UAV is a flying wing type and is able to take off with a little boost. This system happily combines some major advantages taken from planes namely the ability to fly horizontal, at a constant altitude and of course, the great advantage of a long flight-time. The aerodynamic models presented in this paper are optimized to improve the operational performance of this aerial vehicle, especially in terms of stability and the possibility of a long gliding flight-time. Both aspects are very important for the increasing of the goals� efficiency and for the getting work jobs. The presented simulations were obtained using ANSYS 13 installed on our university� cluster system. In a next step the numerical results will be compared with those during experimental flights. This paper presents the main results obtained from numerical simulations and the obtained magnitudes of the main flight coefficients.

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Forensic Investigation of Four Monitored Green Infrastructure Inlets

Water ◽

10.3390/w13131787 ◽

2021 ◽

Vol 13 (13) ◽

pp. 1787

Author(s):

Leena J. Shevade ◽

Franco A. Montalto

Keyword(s):

Measurement Uncertainty ◽

Green Infrastructure ◽

Stormwater Management ◽

Catchment Area ◽

Low Flow ◽

Inflow Rate ◽

Forensic Investigation ◽

Flow Conditions ◽

The Mean

Green infrastructure (GI) is viewed as a sustainable approach to stormwater management that is being rapidly implemented, outpacing the ability of researchers to compare the effectiveness of alternate design configurations. This paper investigated inflow data collected at four GI inlets. The performance of these four GI inlets, all of which were engineered with the same inlet lengths and shapes, was evaluated through field monitoring. A forensic interpretation of the observed inlet performance was conducted using conclusions regarding the role of inlet clogging and inflow rate as described in the previously published work. The mean inlet efficiency (meanPE), which represents the percentage of tributary area runoff that enters the inlet was 65% for the Nashville inlet, while at Happyland the NW inlet averaged 30%, the SW inlet 25%, and the SE inlet 10%, considering all recorded events during the monitoring periods. The analysis suggests that inlet clogging was the main reason for lower inlet efficiency at the SW and NW inlets, while for the SE inlet, performance was compromised by a reverse cross slope of the street. Spatial variability of rainfall, measurement uncertainty, uncertain tributary catchment area, and inlet depression characteristics are also correlated with inlet PE. The research suggests that placement of monitoring sensors should consider low flow conditions and a strategy to measure them. Additional research on the role of various maintenance protocols in inlet hydraulics is recommended.

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Quantifying the Effects of Wave—Current Interactions on Tidal Energy Resource at Sites in the English Channel Using Coupled Numerical Simulations

Energies ◽

10.3390/en14123625 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3625

Author(s):

Jon Hardwick ◽

Ed B. L. Mackay ◽

Ian G. C. Ashton ◽

Helen C. M. Smith ◽

Philipp R. Thies

Keyword(s):

Wave Model ◽

Tidal Energy ◽

English Channel ◽

Flow Conditions ◽

Mean Flow ◽

Radiation Stress ◽

Large Wave ◽

Stress Gradients ◽

The Mean ◽

Flow Power

Numerical modeling of currents and waves is used throughout the marine energy industry for resource assessment. This study compared the output of numerical flow simulations run both as a standalone model and as a two-way coupled wave–current simulation. A regional coupled flow-wave model was established covering the English Channel using the Delft D-Flow 2D model coupled with a SWAN spectral wave model. Outputs were analyzed at three tidal energy sites: Alderney Race, Big Roussel (Guernsey), and PTEC (Isle of Wight). The difference in the power in the tidal flow between coupled and standalone model runs was strongly correlated to the relative direction of the waves and currents. The net difference between the coupled and standalone runs was less than 2.5%. However, when wave and current directions were aligned, the mean flow power was increased by up to 7%, whereas, when the directions were opposed, the mean flow power was reduced by as much as 9.6%. The D-Flow Flexible Mesh model incorporates the effects of waves into the flow calculations in three areas: Stokes drift, forcing by radiation stress gradients, and enhancement of the bed shear stress. Each of these mechanisms is discussed. Forcing from radiation stress gradients is shown to be the dominant mechanism affecting the flow conditions at the sites considered, primarily caused by dissipation of wave energy due to white-capping. Wave action is an important consideration at tidal energy sites. Although the net impact on the flow power was found to be small for the present sites, the effect is site specific and may be significant at sites with large wave exposure or strong asymmetry in the flow conditions and should thus be considered for detailed resource and engineering assessments.

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A Review of Numerical Simulations of Secondary Flows in River Bends

Water ◽

10.3390/w13070884 ◽

2021 ◽

Vol 13 (7) ◽

pp. 884

Author(s):

Rawaa Shaheed ◽

Abdolmajid Mohammadian ◽

Xiaohui Yan

Keyword(s):

Numerical Modeling ◽

Numerical Simulations ◽

Secondary Flow ◽

Cross Section ◽

Turbulence Models ◽

Main Flow ◽

Secondary Flows ◽

River Bends ◽

River Cross Section ◽

River Bend

River bends are one of the common elements in most natural rivers, and secondary flow is one of the most important flow features in the bends. The secondary flow is perpendicular to the main flow and has a helical path moving towards the outer bank at the upper part of the river cross-section, and towards the inner bank at the lower part of the river cross-section. The secondary flow causes a redistribution in the main flow. Accordingly, this redistribution and sediment transport by the secondary flow may lead to the formation of a typical pattern of river bend profile. It is important to study and understand the flow pattern in order to predict the profile and the position of the bend in the river. However, there are a lack of comprehensive reviews on the advances in numerical modeling of bend secondary flow in the literature. Therefore, this study comprehensively reviews the fundamentals of secondary flow, the governing equations and boundary conditions for numerical simulations, and previous numerical studies on river bend flows. Most importantly, it reviews various numerical simulation strategies and performance of various turbulence models in simulating the flow in river bends and concludes that the main problem is finding the appropriate model for each case of turbulent flow. The present review summarizes the recent advances in numerical modeling of secondary flow and points out the key challenges, which can provide useful information for future studies.

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Experimental and numerical investigations on a high-density polyethylene (HDPE) blown film cooling with a new design of the counter-flow/radial jet air-ring

Journal of Plastic Film & Sheeting ◽

10.1177/87560879211026010 ◽

2021 ◽

pp. 875608792110260

Author(s):

ME Ismail ◽

MM Awad ◽

AM Hamed ◽

MY Abdelaal ◽

EB Zeidan

Keyword(s):

Heat Transfer ◽

Numerical Simulations ◽

Film Cooling ◽

Radiation Heat Transfer ◽

Absolute Error ◽

Numerical Results ◽

Upper Lip ◽

Original Design ◽

Blown Film ◽

Set Up

This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD [Formula: see text] turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design.

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The Estimation of Discharge in an Experimental Open Channel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.905.369 ◽

2014 ◽

Vol 905 ◽

pp. 369-373

Author(s):

Choo Tai Ho ◽

Yoon Hyeon Cheol ◽

Yun Gwan Seon ◽

Noh Hyun Suk ◽

Bae Chang Yeon

Keyword(s):

Unsteady Flow ◽

River Discharge ◽

Open Channel ◽

Flow Conditions ◽

Mean Velocity ◽

Velocity Equation ◽

The Mean ◽

Loop Form

The estimation of a river discharge by using a mean velocity equation is very convenient and rational. Nevertheless, a research on an equation calculating a mean velocity in a river was not entirely satisfactory after the development of Chezy and Mannings formulas which are uniform equations. In this paper, accordingly, the mean velocity in unsteady flow conditions which are shown loop form properties was estimated by using a new mean velocity formula derived from Chius 2-D velocity formula. The results showed that the proposed method was more accurate in estimating discharge, when compared with the conventional formulas.

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