Numerical study of flow pattern around lateral intake in a curved channel

2019 ◽  
Vol 30 (11) ◽  
pp. 1950083 ◽  
Author(s):  
Hossien Montaseri ◽  
Hossein Asiaei ◽  
Abdolhossein Baghlani ◽  
Pourya Omidvar
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Flow Pattern ◽  
Numerical Study ◽  
Numerical Models ◽  
Three Dimensional ◽  
Curved Channel ◽  
Channel Bend ◽  
Outer Bank ◽  
Center Region

This paper deals with numerical study of flow field in a channel bend in presence of a lateral intake using three-dimensional numerical model SSIIM2. The effects of bend on the structure of the flow around the intake are investigated and compared with the experimental data. The tests are carried out in a U-shaped channel bend with a lateral intake. The intake is located at the outer bank of an 180∘ bend at position 115∘ with 45∘ diversion angle and the experimental data can be used to calibrate and validate numerical models. The results show that both the center-region and outer-bank cross-stream circulations are observed in the experiments while only the former is captured by the numerical model due to the limitations of the turbulence model. In the curved channel after the intake, both experimental and numerical results show another type of bi-cellular circulations in which clockwise center-region circulations and counterclockwise circulations near the inner bank and the free surface (inner-bank circulations) are captured. The study shows that the numerical model very satisfactorily predicts streamlines, velocity field and flow pattern in the channel and in vicinity of the intake. Investigation of flow pattern around lateral intake in channel bends shows that contrary to the case of flow diversion in straight channels, the width of the dividing stream surface near water surface level is greater than that of near bed level. Finally, the effects of position and diversion angle of the lateral intake, discharge ratio and upstream Froude number on the flow pattern are investigated.

Combined Experimental and Numerical Study for Multiple Microchannel Heat Transfer System

2010 ◽  
Author(s):  
Jingru Zhang ◽  
Yogesh Jaluria ◽  
Tiantian Zhang ◽  
Li Jia
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Steady State ◽  
Numerical Model ◽  
Initial Conditions ◽  
Numerical Study ◽  
Numerical Models ◽  
Three Dimensional ◽  
Variation Versus ◽  
Heat Transfer System

Multiple microchannel heat sinks for potential use for electronic chip cooling are studied experimentally and numerically to characterize their thermal performance. The numerical simulation is driven by experimental data, which are obtained concurrently, to obtain realistic, accurate and validated numerical models. The ultimate goal is to design and optimize thermal systems. The experimental setup was established and liquid flow in the multiple microchannels was studied under different flow rates and heat influx. The temperature variation versus time was recorded by thermocouples, from which the time needed to reach steady state was determined. Temperature variations under steady state conditions were compared with three-dimensional steady state numerical simulation for the same boundary and initial conditions. The experimental data served as input parameters for the validation of the numerical model. In case of discrepancy, the numerical model was improved. A fairly good agreement between the experimental and simulation results was obtained. The numerical model also served to provide input that could be employed to improve and modify the experimental arrangement.

"Barbs" for river bend bank protection: application of a three-dimensional numerical model

2007 ◽  
Vol 34 (9) ◽  
pp. 1087-1095 ◽  
Author(s):  
B Minor ◽  
C D Rennie ◽  
R D Townsend
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Flow Field ◽  
Numerical Models ◽  
Laboratory Data ◽  
Three Dimensional ◽  
Channel Bend ◽  
Bank Protection ◽  
Three Dimensional Models ◽  
Movable Bed

A three-dimensional numerical model was used to examine the turbulent flow field and associated sediment transport due to a series of barbs (submerged groynes) in a channel bend. Model results were in good agreement with measured laboratory data and adequately simulated the important features of sediment transport. Statistical comparison of the predicted and measured equilibrium bed geometry found average regression coefficients of determination of 0.77 and 0.72 for the 90° and 135° channels, respectively. The predicted velocity data followed expected trends. The capability of a three-dimensional numerical model to simulate sediment transport through bend sections of a channel containing barbs was verified. This included the simulation of the effects of different arrangements of barb groups and an analysis of the data to determine the relation of the flow field to associated scour and deposition in a complex fluvial environment. These novel results are useful for improved analyses of the bank-protection capabilities of these structures and for the development and improvement of design guidelines.Key words: three-dimensional models, numerical models, movable bed models, channel bends, turbulence, secondary flow, scour, barbs, groynes.

Experimental and Numerical Study of Mixing in a Hot-Water Storage Tank

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
A. Aviv ◽  
Y. Blyakhman ◽  
O. Beeri ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Numerical Model ◽  
Storage Tank ◽  
Numerical Study ◽  
Tap Water ◽  
Three Dimensional ◽  
Hot Water ◽  
Software Validation ◽  
Water Storage Tank ◽  
Thermal Mixing ◽  
Numerical Investigations

Thermal mixing and stratification are explored numerically and experimentally in a cylindrical tank, which simulates a storage of water heated by a solar collector. The tank is 70cm in height and 24cm in diameter. The inlet and outlet are vertical and located off the centerline of the tank. The study is conducted in a transient mode, namely, the tank is filled with hot water, and as the hot water is being withdrawn, the tap water replaces it in a stratified way or by mixing. The flowrates of 2l∕min, 3l∕min, 5l∕min and 7l∕min, which correspond to superficial velocities of 4.35cm∕min, 6.52cm∕min, 10.87cm∕min, and 15.2cm∕min, are explored. Temperature of hot water ranges within 40–50°C, while the tap water is about 25–27°C. Installation of one and two horizontal baffles above the inlet is examined. Simultaneous experimental and numerical investigations are performed. In the experiment, both flow visualization and temperature measurements are used. Three-dimensional transient numerical simulations are done using the FLUENT 6 software. Validation of the numerical model is achieved by comparison with the experimental results. Then, the numerical model is applied to a study of various possible changes in the system. The results show that at low flowrates, up to a superficial velocity of about 11cm∕min through the tank, the baffles have no effect on tap water mixing with the stored hot water. At higher flowrates, a single horizontal baffle prevents the mixing and preserves the desired stratified temperature distribution in the storage tank.

scholarly journals Comparison of Local and Global Optimization Methods for Calibration of a 3D Morphodynamic Model of a Curved Channel

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1333
Author(s):  
Vahid Shoarinezhad ◽  
Silke Wieprecht ◽  
Stefan Haun
Keyword(s):  
Global Optimization ◽  
Sediment Transport ◽  
Numerical Model ◽  
Numerical Models ◽  
Optimization Algorithms ◽  
Flow Characteristics ◽  
Optimization Methods ◽  
Computational Time ◽  
Curved Channel ◽  
Time Model

In curved channels, the flow characteristics, sediment transport mechanisms, and bed evolution are more complex than in straight channels, owing to the interaction between the centrifugal force and the pressure gradient, which results in the formation of secondary currents. Therefore, using an appropriate numerical model that considers this fully three-dimensional effect, and subsequently, the model calibration are substantial tasks for achieving reliable simulation results. The calibration of numerical models as a subjective approach can become challenging and highly time-consuming, especially for inexperienced modelers, due to dealing with a large number of input parameters with respect to hydraulics and sediment transport. Using optimization methods can notably facilitate and expedite the calibration procedure by reducing the user intervention, which results in a more objective selection of parameters. This study focuses on the application of four different optimization algorithms for calibration of a 3D morphodynamic numerical model of a curved channel. The performance of a local gradient-based method is compared with three global optimization algorithms in terms of accuracy and computational time (model runs). The outputs of the optimization methods demonstrate similar sets of calibrated parameters and almost the same degree of accuracy according to the achieved minimum of the objective function. Accordingly, the most efficient method concerning the number of model runs (i.e., local optimization method) is selected for further investigation by setting up additional numerical models using different sediment transport formulae and various discharge rates. The comparisons of bed topography changes in several longitudinal and cross-sections between the measured data and the results of the calibrated numerical models are presented. The outcomes show an acceptable degree of accuracy for the automatically calibrated models.

Results of the IES Cleanroom Flow Modeling Exercise

1992 ◽  
Vol 35 (2) ◽  
pp. 37-48
Author(s):  
Thomas Kuehn ◽  
David Pui ◽  
James Gratzek
Keyword(s):  
Experimental Data ◽  
Flow Pattern ◽  
Working Group ◽  
Particle Concentration ◽  
Numerical Models ◽  
Computer Applications ◽  
Flow Modeling ◽  
Airflow Velocity ◽  
Velocity Magnitude ◽  
Good Agreement

Six contributed solutions to the Cleanroom Flow Modeling Exercise sponsored by the IES Computer Applications/ Cleanroom Modeling and Evaluation Working Group are compared with each other and with experimental data obtained in a cleanroom configuration similar to that defined in the exercise. Quantitative comparisons are given for time-averaged airflow velocity magnitude and direction and particle concentration. The good agreement between the measured and computed velocity results shows that numerical models can accurately predict the flow pattern in this configuration. However, the particle concentration agreement is not as good.

Study on Three-Dimensional Turbulence Characteristics of Curved Channel Flow

2011 ◽  
Vol 94-96 ◽  
pp. 989-994
Author(s):  
Ri Sheng Wang ◽  
Kai Shi
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Channel Flow ◽  
Average Velocity ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Curved Channel ◽  
Turbulence Characteristics ◽  
Time Average ◽  
Curved Channel Flow

The paper presents an experimental study on three-dimensional turbulence characteristics of curved channel flow by Doppler meter .Measured the time-average velocity and fluctuating intensity and so on. Analysised turbulence characteristics of curved channel flow by the experimental data,and also compared the flow distribution of vertical、horizontal fluctuating intensity,get the conclusion.

A Numerical Study of the Thermal Behaviour of Calibrators for Polymer Extrusion

2006 ◽  
Author(s):  
P. A. M. Lobarinhas ◽  
J. C. F. Teixeira ◽  
S. F. C. F. Teixeira
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Thermal Behavior ◽  
Numerical Study ◽  
Thermal Contact ◽  
Computer Code ◽  
Polymer Processing ◽  
Relevant Variables ◽  
Transient Case ◽  
Great Relevance

In polymer processing by extrusion, the thermal behavior of the components downstream of the extruder dye is of great relevance to the final characteristics of the product. In fact, the process productivity, the product dimensional quality and the physical/mechanical properties are strongly dependent upon the cooling process. In the present work, a numerical model adequate to describe the thermal behavior of the calibrator and the polymer profile is developed and implemented as a computer code. The model is fully 3D, transient and includes a formulation for the polymer movement inside the calibrator based upon the VOF method [1]. Although for practical purposes, a steady solution is desired, the model was implemented as a transient case, to enable its accurate validation with experimental data. The interface between the extrudate and the calibrator is described through a coefficient for the thermal contact resistance. The equations were discretized in a finite volume formulation [2] and the code implemented in Fortran. The good agreement between the model and the experimental data has vindicated the accuracy of the computer model and its subsequent application in the analysis and optimization of complete calibration units. A parametric analysis for the most relevant variables, such as polymer velocity and calibrator length, demonstrated the consistency of the numerical model.

scholarly journals Fire Resistance of Axially Loaded Slender Concrete Filled Steel Tubular Columns – Development of a Three-Dimensional Numerical Model and Comparison with Eurocode 4

10.14311/1089 ◽  
2009 ◽  
Vol 49 (1) ◽  
Author(s):  
A. Espinós ◽  
A. Hospitaler ◽  
M. L. Romero
Keyword(s):  
Numerical Model ◽  
Fire Resistance ◽  
Numerical Models ◽  
Three Dimensional ◽  
Calculation Model ◽  
Construction Technology ◽  
Tubular Columns ◽  
Highly Nonlinear ◽  
Structural Engineers ◽  
Simplified Calculation

In recent years, concrete filled tubular (CFT) columns have become popular among designers and structural engineers, due to a series of highly appreciated advantages: high load-bearing capacity, high seismic resistance, attractive appearance, reduced column footing, fast construction technology and high fire resistance without external protection. In a fire, the degradation of the material properties will cause CFT columns to become highly nonlinear and inelastic, which makes it quite difficult to predict their failure. In fact, it is still not possible for analytical methods to predict with enough accuracy the behaviour of columns of this kind when exposed to fire. Numerical models are therefore widely sought. Many numerical simulations have been carried out worldwide, without obtaining satisfactory results. This work proposes a three-dimensional numerical model for studying the actual fire behaviour of columns of this kind. This model was validated by comparing the simulation results with fire resistance tests carried out by other researchers, as well as with the predictions of the Eurocode 4 simplified calculation model. 

scholarly journals Investigation of the effects of opening size and location on punching shear resistance of flat slabs using Abaqus

2021 ◽  
Vol 15 (4) ◽  
pp. 136-147
Author(s):  
Nguyen Tuan Trung ◽  
Pham Thanh Tung
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Numerical Study ◽  
Shear Resistance ◽  
Design Principles ◽  
Numerical Results ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Flat Slabs ◽  
Abaqus Model

The paper presents a numerical study on the effects of opening size and location on punching shear resistance of flat slabs without drop panels and shear reinforcement using ABAQUS. The study proposes an ABAQUS model that is enable to predict the punching shear resistance of flat slabs with openings. The model is validated well with the experimental data in literature. Using the validated numerical model, the effects of opening size and location on the punching shear resistance of flat slabs are then investigated, and the numerical results are compared with those predicted by ACI 318-19 and TCVN 5574:2018. The comparison between experimental and numerical results shows that the ABAQUS model is reliable. The punching shear resistances calculated by ACI 318-19 and TCVN 5574:2018 with different opening sizes and locations are agreed well to each other, since the design principles between two codes now are similar.

Two Numerical Models for Prediction of an Industrial Concasting Process

2003 ◽  
Author(s):  
Frantisek Kavicka ◽  
Josef Stetina ◽  
Karel Stransky ◽  
Jana Dobrovska ◽  
Vera Dobrovska ◽  
...  
Keyword(s):  
Temperature Field ◽  
Numerical Model ◽  
Numerical Models ◽  
Three Dimensional ◽  
Crystallization Rate ◽  
Dendritic Segregation ◽  
Distribution Of Elements ◽  
Technological Impact ◽  
The Mean ◽  
Constituent Elements

This paper introduces the application of two three-dimensional (3D) numerical models of the temperature field of a caster. The first model simulates the temperature field of a caster—either as a whole, or any of its parts. Experimental research and data acquisition take place simultaneously with the numerical computation in order to enhance the numerical model and to perfect it in the course of the process. In order to apply the second original numerical model—a model of dendritic segregation of elements—it is necessary to analyze the heterogeneity of samples of the constituent elements and impurities in characteristic places of the solidifying slab. The samples are taken from places, which provide information on the distribution of elements under both standard and extreme conditions for solidification, where the mean solidification (crystallization) rate is known for points between the solidus and liquidus curves. Using this method, it is possible to forecast the occurrence of the critical points of a slab from the viewpoint of its susceptibility to crack and fissure. Verification of the technological impact of optimization, resulting from both models, is conducted on a real industrial caster.

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