This page has only limited features, please log in for full access.
Anchored Large Woody Debris (LWD) is increasingly being used as one of several nature-based coastal protection strategies along the north-western coasts of Canada and the US. As an alternative to conventional hard armoring (e.g., seawalls), its usage is widely considered to be less harmful to the coastal ecosystem while maintaining the ability to protect the beaches against wave attack and erosion. The effects of seawalls on beaches have been extensively studied; however, the performance and efficacy of LWD and its potential as a suitable alternative to seawalls (and other shoreline protection structures) are still understudied in current research. This paper presents and compares the effects of a conventional vertical seawall with two different LWD structures on beach morphology and wave reflection through large-scale physical modeling in a wave flume at a 1:5 scale. An assessment of techniques used to measure beach morphology and an assessment of model effects were included in the study. It was found that the wave reflection could be reduced by using a single log instead of a wall structure, while changes in the beach morphology response largely depended on the type of the LWD structure. A stacked log wall showed near-identical behavior as a conventional seawall. Visible model effects from the experiments, including the effect of the flume sidewalls on the beach morphology, were quantified and analyzed to inform future research.
Pauline Falkenrich; Jessica Wilson; Ioan Nistor; Nils Goseberg; Andrew Cornett; Abdolmajid Mohammadian. Nature-Based Coastal Protection by Large Woody Debris as Compared to Seawalls: A Physical Model Study of Beach Morphology and Wave Reflection. Water 2021, 13, 2020 .
AMA StylePauline Falkenrich, Jessica Wilson, Ioan Nistor, Nils Goseberg, Andrew Cornett, Abdolmajid Mohammadian. Nature-Based Coastal Protection by Large Woody Debris as Compared to Seawalls: A Physical Model Study of Beach Morphology and Wave Reflection. Water. 2021; 13 (15):2020.
Chicago/Turabian StylePauline Falkenrich; Jessica Wilson; Ioan Nistor; Nils Goseberg; Andrew Cornett; Abdolmajid Mohammadian. 2021. "Nature-Based Coastal Protection by Large Woody Debris as Compared to Seawalls: A Physical Model Study of Beach Morphology and Wave Reflection." Water 13, no. 15: 2020.
River confluences are a common feature in natural water resources. The flow characteristics in confluences are complicated, especially at junction areas between tributaries and the main river. One of the typical characteristics of confluences is secondary flow, which plays an important role in mixing, velocity, sediment transport, and pollutant dispersion. In addition to the experimental and field studies that have been conducted in this area, the development of computational fluid dynamics has allowed researchers in this field to use different numerical models to simulate turbulence properties in rivers, especially secondary flows. Nowadays, the hydrodynamics of flows in confluences are widely simulated by using three-dimensional models in order to fully capture the flow structures, as the flow characteristics are considered to be turbulent and three-dimensional at river junctions. Several numerical models have been recommended for this purpose, and various turbulence models have been used to simulate the flows at confluences. To assess the accuracy of turbulence models, flows have been predicted by applying different turbulence models in the numerical model and the results have been compared with other data, such as field, laboratory, and experimental data. The purpose behind these investigations was to find the suitable model for each case of turbulent flow and for different types of confluences. In this study, the performances of turbulence models for confluences are reviewed for different numerical simulation strategies.
Rawaa Shaheed; Xiaohui Yan; Abdolmajid Mohammadian. Review and Comparison of Numerical Simulations of Secondary Flow in River Confluences. Water 2021, 13, 1917 .
AMA StyleRawaa Shaheed, Xiaohui Yan, Abdolmajid Mohammadian. Review and Comparison of Numerical Simulations of Secondary Flow in River Confluences. Water. 2021; 13 (14):1917.
Chicago/Turabian StyleRawaa Shaheed; Xiaohui Yan; Abdolmajid Mohammadian. 2021. "Review and Comparison of Numerical Simulations of Secondary Flow in River Confluences." Water 13, no. 14: 1917.
Herein, the free surface flow over a broad-crested weir under different hydraulic heads was investigated. A series of experiments were conducted in a 5-m-long-flume to measure the 3D velocity profile around a rectangular weir using Acoustic Doppler Velocimetry (ADV). The efforts were undertaken to simulate the hydrodynamic field over the weir using open-source toolbox OpenFOAM with five turbulence models including standard k-ε, RNG k-ε, realizable k-ε, k-ω SST and LRR. The numerical results were compared to the experimental data obtained from laboratory measurements. It demonstrated that the k-ω SST and LRR models had the best performance in cases dealing with vortices. Then, separation zone patterns at three locations: behind, over and in front of the weir under different head ratios were examined. It was found that changing the head ratio does not have a notable effect on the relative dimension of separation flow over the weir, whereas the separation zone located behind and in front of the weir grew linearly. After raising the head ratio, the downstream separation zone was split into two significant vortices rotating oppositely. Discharge coefficients are calculated for a wide range of head ratios. It was concluded that Cd equaled 0.85 for head ratios up to 0.3 and then grew to 1.0 by increasing the head ratio.
Hanifeh Imanian; Abdolmajid Mohammadian; Pouneh Hoshyar. Experimental and numerical study of flow over a broad-crested weir under different hydraulic head ratios. Flow Measurement and Instrumentation 2021, 80, 102004 .
AMA StyleHanifeh Imanian, Abdolmajid Mohammadian, Pouneh Hoshyar. Experimental and numerical study of flow over a broad-crested weir under different hydraulic head ratios. Flow Measurement and Instrumentation. 2021; 80 ():102004.
Chicago/Turabian StyleHanifeh Imanian; Abdolmajid Mohammadian; Pouneh Hoshyar. 2021. "Experimental and numerical study of flow over a broad-crested weir under different hydraulic head ratios." Flow Measurement and Instrumentation 80, no. : 102004.
Modeling spatial distribution of flow depth in fluvial systems is crucial for flow mitigation, river rehabilitation, and design of water resources infrastructure. Flow depth in fluvial systems can be typically estimated using hydrological or physics-based hydraulic models. However, hydrological models may not be able to provide satisfactory predictions for catchments with limited data because they normally ignored the strict conservation of momentum. Traditional fully physics-based hydraulic models are often very computationally expensive, limiting their wide usage in practical applications. In this study, a novel method, based on a hybrid two-dimensional (2D) hydraulic-multigene genetic programming (MGGP) approach, is proposed and employed to model the spatial distribution of flow depth in fluvial systems. A 2D hydraulic model was constructed using the TELEMAC-2D software and validated against field measurements. The validated model was then assumed to reflect the real physical processes and utilized to carry out additional computations to obtain spatial distribution of flow depth under different discharge scenarios, which provided a sufficient synthetic dataset for training machine learning models based on the MGGP technique. The study area (a segment of the Ottawa River near the island named Île Kettle) was divided into 34 sub-regions to further reduce the computational costs of the training processes and the complexity of the evolved models. The numerical data were distributed to the corresponding sub-regions, and an MGGP-based model was trained for each sub-region. These models are compact explicit arithmetic equations that can be readily transferable and can immediately output the flow depth at any point in the corresponding sub-region as functions of the flow rate, longitudinal, and transversal coordinates. The best MGGP model for each sub-region amongst all the generated models was identified using the Pareto optimization approach. The results showed that the best MGGP models satisfactorily reproduced the training data and predicted the testing data (the root mean square errors were 0.303 m and 0.306 m, respectively), demonstrating the predictive capability of the approach. A comparison between MGGP and single-gene genetic programming (SGGP) approaches and confidence analysis were also reported, which demonstrated the good performance of the proposed approach. Furthermore, it took about 53 min for the hydraulic model to complete each simulation, but it took only about 0.56 s using the final model; the total size of the hydraulic output files for 12 different sizes was 432, 948 KB, but the total size of the script file for the final model was only about 46 KB. Therefore, the present study found that the hybrid 2D hydraulic-MGGP approach was satisfactorily accurate, fast to run, and easy to use, and thus, it is a promising tool for modeling spatial distribution of flow depth in fluvial systems.
Xiaohui Yan; Abdolmajid Mohammadian; Ali Khelifa. Modeling spatial distribution of flow depth in fluvial systems using a hybrid two-dimensional hydraulic-multigene genetic programming approach. Journal of Hydrology 2021, 600, 126517 .
AMA StyleXiaohui Yan, Abdolmajid Mohammadian, Ali Khelifa. Modeling spatial distribution of flow depth in fluvial systems using a hybrid two-dimensional hydraulic-multigene genetic programming approach. Journal of Hydrology. 2021; 600 ():126517.
Chicago/Turabian StyleXiaohui Yan; Abdolmajid Mohammadian; Ali Khelifa. 2021. "Modeling spatial distribution of flow depth in fluvial systems using a hybrid two-dimensional hydraulic-multigene genetic programming approach." Journal of Hydrology 600, no. : 126517.
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.
Rawaa Shaheed; Abdolmajid Mohammadian; Xiaohui Yan. A Review of Numerical Simulations of Secondary Flows in River Bends. Water 2021, 13, 884 .
AMA StyleRawaa Shaheed, Abdolmajid Mohammadian, Xiaohui Yan. A Review of Numerical Simulations of Secondary Flows in River Bends. Water. 2021; 13 (7):884.
Chicago/Turabian StyleRawaa Shaheed; Abdolmajid Mohammadian; Xiaohui Yan. 2021. "A Review of Numerical Simulations of Secondary Flows in River Bends." Water 13, no. 7: 884.
In order to measure flow rate in open channels, including irrigation channels, hydraulic structures are used with a relatively high degree of reliance. Venturi flumes are among the most common and efficient type, and they can measure discharge using only the water level at a specific point within the converging section and an empirical discharge relationship. There have been a limited number of attempts to simulate a venturi flume using computational fluid dynamics (CFD) tools to improve the accuracy of the readings and empirical formula. In this study, simulations on different flumes were carried out using a total of seven different models, including the standard k–ε, RNG k–ε, realizable k–ε, k–ω, and k–ω SST models. Furthermore, large-eddy simulation (LES) and detached eddy simulation (DES) were performed. Comparison of the simulated results with physical test data shows that among the turbulence models, the k–ε model provides the most accurate results, followed by the dynamic k LES model when compared to the physical experimental data. The overall margin of error was around 2–3%, meaning that the simulation model can be reliably used to estimate the discharge in the channel. In different cross-sections within the flume, the k–ε model provides the lowest percentage of error, i.e., 1.93%. This shows that the water surface data are well calculated by the model, as the water surface profiles also follow the same vertical curvilinear path as the experimental data.
Mehdi Heyrani; Abdolmajid Mohammadian; Ioan Nistor; Omerul Dursun. Numerical Modeling of Venturi Flume. Hydrology 2021, 8, 27 .
AMA StyleMehdi Heyrani, Abdolmajid Mohammadian, Ioan Nistor, Omerul Dursun. Numerical Modeling of Venturi Flume. Hydrology. 2021; 8 (1):27.
Chicago/Turabian StyleMehdi Heyrani; Abdolmajid Mohammadian; Ioan Nistor; Omerul Dursun. 2021. "Numerical Modeling of Venturi Flume." Hydrology 8, no. 1: 27.
Significant environmental effects from the use of marine outfall discharges have led to increased efforts by both regulatory bodies and research groups to minimize the negative impacts of discharges on the receiving water bodies. Understanding the characteristics of discharges under conditions representative of marine environments can enhance the management of discharges and mitigate the adverse impacts to marine biota. Thus, special attention should be given to ambient cross-flow effects on the mixing behaviors of jet discharges. A buoyant jet in cross-flow has different practical applications such as film cooling and dilution, and provide a higher mixing capability in comparison with free jets or discharges into stationary environments. The main reason for this is believed to be the existence of various complicated vortical structures including a counter-rotating vortex pair as the jet expands downstream. Although tremendous research efforts have been devoted to buoyant jets issuing into cross-flows over the past five decades, the mixing process of an effluent at the discharge point is not yet well understood because of the highly complex fluid interactions and dispersion patterns involved. Therefore, there is a need for a deeper understanding of buoyant jets in cross-flows in order to obtain better predictive methods and more accurate design guidelines. The main aims of this study were (i) to establish the background behind the subject of buoyant jets in cross-flows including the flow structures resulting from the interaction of jets and cross-flows and the impacts of current on mixing and transport behavior; (ii) to present a summary of relevant experimental and numerical research efforts; and finally, (iii) to identify and discuss research gaps and future research directions.
Mostafa Taherian; Abdolmajid Mohammadian. Buoyant Jets in Cross-Flows: Review, Developments, and Applications. Journal of Marine Science and Engineering 2021, 9, 61 .
AMA StyleMostafa Taherian, Abdolmajid Mohammadian. Buoyant Jets in Cross-Flows: Review, Developments, and Applications. Journal of Marine Science and Engineering. 2021; 9 (1):61.
Chicago/Turabian StyleMostafa Taherian; Abdolmajid Mohammadian. 2021. "Buoyant Jets in Cross-Flows: Review, Developments, and Applications." Journal of Marine Science and Engineering 9, no. 1: 61.
Liquid storage tanks subjected to base excitation can cause large impact forces on the tank roof, which can lead to structural damage as well as economic and environmental losses. The use of artificial intelligence in solving engineering problems is becoming popular in various research fields, and the Genetic Programming (GP) method is receiving more attention in recent years as a regression tool and also as an approach for finding empirical expressions between the data. In this study, an OpenFOAM numerical model that was validated by the authors in a previous study is used to simulate various tank sizes with different liquid heights. The tanks are excited in three different orientations with harmonic sinusoidal loadings. The excitation frequencies are chosen as equal to the tanks’ natural frequencies so that they would be subject to a resonance condition. The maximum pressure in each case is recorded and made dimensionless; then, using Multi-Gene Genetic Programming (MGGP) methods, a relationship between the dimensionless maximum pressure and dimensionless liquid height is acquired. Finally, some error measurements are calculated, and the sensitivity and uncertainty of the proposed equation are analyzed.
Iman Bahreini Toussi; Abdolmajid Mohammadian; Reza Kianoush. Prediction of Maximum Pressure at the Roofs of Rectangular Water Tanks Subjected to Harmonic Base Excitation Using the Multi-Gene Genetic Programming Method. Mathematical and Computational Applications 2021, 26, 6 .
AMA StyleIman Bahreini Toussi, Abdolmajid Mohammadian, Reza Kianoush. Prediction of Maximum Pressure at the Roofs of Rectangular Water Tanks Subjected to Harmonic Base Excitation Using the Multi-Gene Genetic Programming Method. Mathematical and Computational Applications. 2021; 26 (1):6.
Chicago/Turabian StyleIman Bahreini Toussi; Abdolmajid Mohammadian; Reza Kianoush. 2021. "Prediction of Maximum Pressure at the Roofs of Rectangular Water Tanks Subjected to Harmonic Base Excitation Using the Multi-Gene Genetic Programming Method." Mathematical and Computational Applications 26, no. 1: 6.
Liquid-containing structures are used for various municipal and industrial applications. The functionality of these structures in seismic regions is crucial. The main purpose of this study is to investigate the behavior of liquid under seismic excitations using numerical modelling. For this purpose, experimental and numerical studies are conducted. In the experimental tests, a ground-supported rectangular tank is excited on a shaking table. The tests are videotaped from two directions and subsequently analyzed frame-by-frame. Four different orientations are tested to investigate the effect of bilateral excitation. In the numerical simulations, the same tank is modeled in OpenFOAM—a computational fluid dynamics program—and the same excitations are applied. The results from the numerical and the experimental studies are compared, and reliability of the numerical model is discussed. Furthermore, using the numerical model, the pressure on the roof of the tank is obtained at various locations and examined for different excitations.
Iman Bahreini Toussi; Reza Kianoush; Abdolmajid Mohammadian. Numerical and Experimental Investigation of Rectangular Liquid-Containing Structures under Seismic Excitation. Infrastructures 2020, 6, 1 .
AMA StyleIman Bahreini Toussi, Reza Kianoush, Abdolmajid Mohammadian. Numerical and Experimental Investigation of Rectangular Liquid-Containing Structures under Seismic Excitation. Infrastructures. 2020; 6 (1):1.
Chicago/Turabian StyleIman Bahreini Toussi; Reza Kianoush; Abdolmajid Mohammadian. 2020. "Numerical and Experimental Investigation of Rectangular Liquid-Containing Structures under Seismic Excitation." Infrastructures 6, no. 1: 1.
Combining multiple modules into one framework is a key step in modelling a complex system. In this study, rather than focusing on modifying a specific model, we studied the performance of different calculation structures in a multi-objective optimization framework. The Hydraulic and Risk Combined Model (HRCM) combines hydraulic performance and pipe breaking risk in a drainage system to provide optimal rehabilitation strategies. We evaluated different framework structures for the HRCM model. The results showed that the conventional framework structure used in engineering optimization research, which includes (1) constraint functions; (2) objective functions; and (3) multi-objective optimization, is inefficient for drainage rehabilitation problem. It was shown that the conventional framework can be significantly improved in terms of calculation speed and cost-effectiveness by removing the constraint function and adding more objective functions. The results indicated that the model performance improved remarkably, while the calculation speed was not changed substantially. In addition, we found that the mixed-integer optimization can decrease the optimization performance compared to using continuous variables and adding a post-processing module at the last stage to remove the unsatisfying results. This study (i) highlights the importance of the framework structure inefficiently solving engineering problems, and (ii) provides a simplified efficient framework for engineering optimization problems.
Xiatong Cai; Abdolmajid Mohammadian; Hamidreza Shirkhani. An Efficient Framework for Multi-Objective Risk-Informed Decision Support Systems for Drainage Rehabilitation. Mathematical and Computational Applications 2020, 25, 73 .
AMA StyleXiatong Cai, Abdolmajid Mohammadian, Hamidreza Shirkhani. An Efficient Framework for Multi-Objective Risk-Informed Decision Support Systems for Drainage Rehabilitation. Mathematical and Computational Applications. 2020; 25 (4):73.
Chicago/Turabian StyleXiatong Cai; Abdolmajid Mohammadian; Hamidreza Shirkhani. 2020. "An Efficient Framework for Multi-Objective Risk-Informed Decision Support Systems for Drainage Rehabilitation." Mathematical and Computational Applications 25, no. 4: 73.
Evaporation plays a significant role in the hydrologic cycle, and thus the estimation of evaporative demand is crucial for water resources management and irrigation scheduling. Evaporation is subjected to the effects of global climate change, which can be quantified by the representative concentration pathway (RCP) scenarios. However, forecasts of future daily pan evaporation under RCP climate change scenarios using a temperature-based pan evaporation model and downscaled temperature forecasts for an arid region (e.g., Qatar) have rarely been reported in the literature. The present study provides estimations of future daily pan evaporation in Qatar under four RCP climate change scenarios for the period January 1, 2018 to December 31, 2050. Modelled maximum and minimum daily temperature data from a general circulation model (GCM) within the Coupled Model Intercomparison Project Phase 5 (CMIP5) experimental framework are extracted and downscaled using the Quantiles-matching approach. A pan evaporation model coupling the Hargreaves potential evapotranspiration model and a Class A pan coefficient model is calibrated against observed pan evaporation data and utilized to estimate future daily pan evaporation in the study area using downscaled daily temperature. Various measures of fit are employed to evaluate the performance of the downscaling approach and pan evaporation model, and the results show that the performance of the downscaling approach and pan evaporation method are both satisfactory. The study also finds that the pan evaporation increased fastest under the RCP60 scenario, and the average increase in pan evaporation was roughly 0.01095 mm/day per year. The study provides datasets for future pan evaporation for the period between 2018 and 2050 that can be useful for the development of numerical hydrologic models, management of water resources, and irrigation scheduling.
Xiaohui Yan; Abdolmajid Mohammadian. Estimating future daily pan evaporation for Qatar using the Hargreaves model and statistically downscaled global climate model projections under RCP climate change scenarios. Arabian Journal of Geosciences 2020, 13, 1 -15.
AMA StyleXiaohui Yan, Abdolmajid Mohammadian. Estimating future daily pan evaporation for Qatar using the Hargreaves model and statistically downscaled global climate model projections under RCP climate change scenarios. Arabian Journal of Geosciences. 2020; 13 (18):1-15.
Chicago/Turabian StyleXiaohui Yan; Abdolmajid Mohammadian. 2020. "Estimating future daily pan evaporation for Qatar using the Hargreaves model and statistically downscaled global climate model projections under RCP climate change scenarios." Arabian Journal of Geosciences 13, no. 18: 1-15.
In this paper, a type of pile breakwater is studied in a configuration that can provide an effective shore protection structure. While, the rubble mound breakwaters are the most common type, but they suffer from a number of shortcomings including the interruption of water that may lead to deterioration of water quality and corresponding environmental problems. The breakwater of this study with rows of piles can be used against sea waves, as an alternative. Its hydraulic performance, including wave reflection and transmission, shear stresses, pressure measurements, drag and inertia coefficients are investigated. In the first step, the hydrodynamics around the mono-piles with square cross-sections are inspected. The parametric equations are developed to measure the optimal orientation of the piles. As evidenced in the literature, relatively limited works have been carried out on this kind of piles. Also, the performance of the considered pile breakwaters are evaluated. To do this, the numerical results are calibrated and validated by experimentation. It is observed that the group piles with the square cross-section in optimum conditions, could have a higher value of reflection almost between 7 even to almost 30 percent, than other considered conditions with mild and short waves. It can be related to the effect of the square piles edges on the separation process of the flow.
Alireza Mojtahedi; Mehrdad Shokatian Beiragh; Ismail Farajpour; Majid Mohammadian. Investigation on hydrodynamic performance of an environmentally friendly pile breakwater. Ocean Engineering 2020, 217, 107942 .
AMA StyleAlireza Mojtahedi, Mehrdad Shokatian Beiragh, Ismail Farajpour, Majid Mohammadian. Investigation on hydrodynamic performance of an environmentally friendly pile breakwater. Ocean Engineering. 2020; 217 ():107942.
Chicago/Turabian StyleAlireza Mojtahedi; Mehrdad Shokatian Beiragh; Ismail Farajpour; Majid Mohammadian. 2020. "Investigation on hydrodynamic performance of an environmentally friendly pile breakwater." Ocean Engineering 217, no. : 107942.
This paper presents a model for local scour at submerged weirs with downstream slopes that uses a coupled moving-mesh and masked-element approach. In the developed model, the fluid-sediment interface is tracked using a moving-mesh technique, and the effects of the structure on the hydrodynamics and bed morphology are resolved using a masked-element technique. Compared to traditional sediment scour models, based on the moving-mesh technique, the present model has the advantage of allowing for a simpler setup of the computational grids and a larger-amplitude deformation. Laboratory experiments on local scour at a submerged weir with a downstream slope were conducted, which provided bed profiles at different time instants. The results obtained by the present model are compared to the experimental data. The comparisons demonstrate the performance of the model in satisfactorily predicting local scour at a submerged weir with a downstream slope. The model was further modified and employed to carry out additional computations to investigate the influence of various parameters and sub-models.
Xiaohui Yan; Colin David Rennie; Abdolmajid Mohammadian. Numerical modeling of local scour at a submerged weir with a downstream slope using a coupled moving-mesh and masked-element approach. International Journal of Sediment Research 2020, 36, 279 -290.
AMA StyleXiaohui Yan, Colin David Rennie, Abdolmajid Mohammadian. Numerical modeling of local scour at a submerged weir with a downstream slope using a coupled moving-mesh and masked-element approach. International Journal of Sediment Research. 2020; 36 (2):279-290.
Chicago/Turabian StyleXiaohui Yan; Colin David Rennie; Abdolmajid Mohammadian. 2020. "Numerical modeling of local scour at a submerged weir with a downstream slope using a coupled moving-mesh and masked-element approach." International Journal of Sediment Research 36, no. 2: 279-290.
We present an adaptive well-balanced positivity preserving central-upwind scheme on quadtree grids for shallow water equations. The use of quadtree grids results in a robust, efficient and highly accurate numerical method. The quadtree model is developed based on the well-balanced positivity preserving central-upwind scheme proposed in [A. Kurganov and G. Petrova, Commun. Math. Sci., 5 (2007), pp. 133–160]. The designed scheme is well-balanced in the sense that it is capable of exactly preserving “lake-at-rest” steady states. In order to achieve this as well as to preserve positivity of water depth, a continuous piecewise bilinear interpolation of the bottom topography function is utilized. This makes the proposed scheme capable of modelling flows over discontinuous bottom topography. Local gradients are examined to determine new seeding points in grid refinement for the next timestep. Numerical examples demonstrate the promising performance of the central-upwind quadtree scheme.
Mohammad A. Ghazizadeh; Abdolmajid Mohammadian; Alexander Kurganov. An adaptive well-balanced positivity preserving central-upwind scheme on quadtree grids for shallow water equations. Computers & Fluids 2020, 208, 104633 .
AMA StyleMohammad A. Ghazizadeh, Abdolmajid Mohammadian, Alexander Kurganov. An adaptive well-balanced positivity preserving central-upwind scheme on quadtree grids for shallow water equations. Computers & Fluids. 2020; 208 ():104633.
Chicago/Turabian StyleMohammad A. Ghazizadeh; Abdolmajid Mohammadian; Alexander Kurganov. 2020. "An adaptive well-balanced positivity preserving central-upwind scheme on quadtree grids for shallow water equations." Computers & Fluids 208, no. : 104633.
The influence of channel side slope on flow in strongly curved channel bends is studied numerically. The performances of five different turbulence models are investigated. Comparison to experimental measurements demonstrates that the fully 3D numerical model can reliably simulate a channel bend flow field. Among the tested turbulence models, the realizable k − ε model performed best. The present study also demonstrates that the realizable k − ε model can satisfactorily predict smaller flow features in bend flow, such as the outer-bank circulation cell. The validated model is employed to carry out additional computations for channel bends with different side slopes. It is found that the number, position, and strength of secondary flow cells varies with the channel side slope, with corresponding influence on flow distribution and flow vorticity.
Xiaohui Yan; Colin D. Rennie; Abdolmajid Mohammadian. A three-dimensional numerical study of flow characteristics in strongly curved channel bends with different side slopes. Environmental Fluid Mechanics 2020, 20, 1491 -1510.
AMA StyleXiaohui Yan, Colin D. Rennie, Abdolmajid Mohammadian. A three-dimensional numerical study of flow characteristics in strongly curved channel bends with different side slopes. Environmental Fluid Mechanics. 2020; 20 (6):1491-1510.
Chicago/Turabian StyleXiaohui Yan; Colin D. Rennie; Abdolmajid Mohammadian. 2020. "A three-dimensional numerical study of flow characteristics in strongly curved channel bends with different side slopes." Environmental Fluid Mechanics 20, no. 6: 1491-1510.
Wastewater discharges are widespread in industrial and natural environments, and since these discharges may cause serious impacts on the environment and ecological systems, it is important to investigate their mixing processes. The receiving fluids in many practical simulations are often stratified, and the stratification may significantly affect the mixing processes of the wastewater jets, so the mechanisms of wastewater discharges in stratified fluids are quite different from those in a homogeneous environment, and thus well-established theories and models cannot be used for predicting jets in a stratified environment. In this study, a numerical model with the re-normalization group (RNG) k-ε turbulence closure is used to model inclined plane jets in a linearly stratified environment. The characteristic parameters obtained from the experiments and simulations are compared, and the good match demonstrates the capability of the model in modeling inclined plane jets in a linearly stratified environment. The study also proposes new empirical functions, based on a dimensional analysis, for the characteristic parameters, and the proposed functions can be employed for a quick estimation of the important parameters of inclined plane jets in a linearly stratified environment.
Xiaohui Yan; Abdolmajid Mohammadian; Xin Chen. Numerical modeling of inclined plane jets in a linearly stratified environment. Alexandria Engineering Journal 2020, 59, 1857 -1867.
AMA StyleXiaohui Yan, Abdolmajid Mohammadian, Xin Chen. Numerical modeling of inclined plane jets in a linearly stratified environment. Alexandria Engineering Journal. 2020; 59 (3):1857-1867.
Chicago/Turabian StyleXiaohui Yan; Abdolmajid Mohammadian; Xin Chen. 2020. "Numerical modeling of inclined plane jets in a linearly stratified environment." Alexandria Engineering Journal 59, no. 3: 1857-1867.
The forecasting performance for daily reference evapotranspiration (ET0) at six weather stations in Canada using the Penman–Monteith (P–M) model and statistically downscaled global climate model (GCM) projections was evaluated and quantified. The observational daily weather data for ET0 calculations, including the daily air temperature (Ta), solar radiation (Rs), wind speed (Uw), and relative humidity (RH), were collected. The GCM data obtained by the ESM2M model for the same variables, period, and stations were extracted and downscaled using the Quantiles–matching approach. The forecasting performance for the weather variables was quantified, and the results showed that the raw GCM data for Rs and Ta over Canada matched the observations very well, but the GCM performed relatively worse in forecasting Uw and RH. The Quantiles–matching downscaling approach can significantly improve the forecast accuracy of the meteorological variables. The ET0 calculated using the raw GCM or downscaled GCM data were then compared with those computed with the observational data. The results demonstrated that the daily ET0 over Canada can be satisfactorily forecasted using the P–M model and statistically downscaled GCM projections.
Xiaohui Yan; Abdolmajid Mohammadian. Forecasting daily reference evapotranspiration for Canada using the Penman–Monteith model and statistically downscaled global climate model projections. Alexandria Engineering Journal 2020, 59, 883 -891.
AMA StyleXiaohui Yan, Abdolmajid Mohammadian. Forecasting daily reference evapotranspiration for Canada using the Penman–Monteith model and statistically downscaled global climate model projections. Alexandria Engineering Journal. 2020; 59 (2):883-891.
Chicago/Turabian StyleXiaohui Yan; Abdolmajid Mohammadian. 2020. "Forecasting daily reference evapotranspiration for Canada using the Penman–Monteith model and statistically downscaled global climate model projections." Alexandria Engineering Journal 59, no. 2: 883-891.
Effluent discharge mixing and dispersion have been studied for many decades. Studies began with experimental investigations of geometrical and concentration characteristics of the jets in the near-field zone. More robust experiments were performed using Laser-Induced Fluorescence (LIF) and Particle Image Velocimetry (PIV) systems starting in the 20th century, which led to more accurate measurement and analysis of jet behavior. The advancement of computing systems over the past two decades has led to the development of various numerical methods, which have been implemented in Computational Fluid Dynamics (CFD) codes to predict fluid motion and characteristics. Numerical modeling of mixing and dispersion is increasingly preferred over laboratory experiments of effluent discharges in both academia and industry. More computational resources and efficient numerical schemes have helped increase the popularity of using CFD models in jet and plume modeling. Numerous models have been developed over time, each with different capabilities to facilitate the investigation of all aspects of effluent discharges. Among these, Reynolds-averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES) are at present the most popular CFD models employing effluent discharge modeling. This paper reviews state-of-the-art numerical modeling studies for different types and configurations of discharges, including positively and negatively buoyant discharges, which have mostly been completed over the past two decades. The numerical results of these studies are summarized and critically discussed in this review. Various aspects related to the impact of turbulence models, such as k-ε and Launder-Reece-Rodi (LRR) models, are reviewed herein. RANS and LES models are reviewed, and implications for the simulation of jet and plume mixing are discussed to develop a reference for future researchers performing numerical investigations on jet mixing and dispersion.
Abdolmajid Mohammadian; Hossein Kheirkhah Gildeh; Ioan Nistor. CFD Modeling of Effluent Discharges: A Review of Past Numerical Studies. Water 2020, 12, 856 .
AMA StyleAbdolmajid Mohammadian, Hossein Kheirkhah Gildeh, Ioan Nistor. CFD Modeling of Effluent Discharges: A Review of Past Numerical Studies. Water. 2020; 12 (3):856.
Chicago/Turabian StyleAbdolmajid Mohammadian; Hossein Kheirkhah Gildeh; Ioan Nistor. 2020. "CFD Modeling of Effluent Discharges: A Review of Past Numerical Studies." Water 12, no. 3: 856.
In some outfall systems, wastewaters are discharged into ambient water bodies using rosette-type diffusers in the form of multiple buoyant jets, and it is essential to simulate their mixing characteristics for practical applications and optimal design purposes. The mixing processes of a rosette jet group are more complicated than single jets and multiple horizontal or vertical jets, and thus the existing methods cannot be effectively used to simulate their mixing and dilution properties. With the recent advancements in numerical modeling approaches, numerical simulation of wastewater jets as three-dimensional phenomena can be feasible. The present study deals with a fully three-dimensional numerical simulation for buoyant jets discharged from a rosette-type multiport diffuser, with the standard and re-normalization group (RNG) k-ε turbulence models. The simulated results are compared with experimental data, and the results show a good agreement with the experimental data, demonstrating that the numerical model is an efficient and effective tool for simulating rosette jet groups. It was also concluded that the RNG k-ε model leads to better results than the standard k-ε model with a comparable computational cost. The validated model was further utilized to investigate the influences of port inclinations on the mixing behaviors.
Xiaohui Yan; Abdolmajid Mohammadian; Xin Chen. Three-Dimensional Numerical Simulations of Buoyant Jets Discharged from a Rosette-Type Multiport Diffuser. Journal of Marine Science and Engineering 2019, 7, 409 .
AMA StyleXiaohui Yan, Abdolmajid Mohammadian, Xin Chen. Three-Dimensional Numerical Simulations of Buoyant Jets Discharged from a Rosette-Type Multiport Diffuser. Journal of Marine Science and Engineering. 2019; 7 (11):409.
Chicago/Turabian StyleXiaohui Yan; Abdolmajid Mohammadian; Xin Chen. 2019. "Three-Dimensional Numerical Simulations of Buoyant Jets Discharged from a Rosette-Type Multiport Diffuser." Journal of Marine Science and Engineering 7, no. 11: 409.
Wastewaters are often discharged into water bodies from multiport diffusers in the form of inclined dense jets, and it is important to predict their mixing characteristics for a sound sustainable design for seawater desalination. Compared with single jets and multiple horizontal or vertical jets, the mixing processes of multiple inclined dense jets are more complicated, and thus the existing theoretical, analytical, or simplified numerical methods cannot effectively predict their dilution properties. Recent advances in numerical modeling techniques have provided a new avenue of simulating wastewater jets as three-dimensional phenomena, but their application to multiple inclined dense jets has rarely been reported. In this study, a fully three-dimensional numerical model is employed to simulate multiple inclined brine discharges from diffusers with moderately spaced ports, with the standard and re-normalization group (RNG) k-ε turbulence closures being tested. The simulated characteristic variables are compared to experimental data, and the results show that the simulations match very well with the experiments, demonstrating that the numerical model is a promising tool for simulating inclined dense jets discharged from multiport diffusers. The study also found that the RNG k-ε model performs better than the standard k-ε model without significantly increasing the computational costs.
Xiaohui Yan; Abdolmajid Mohammadian; Yan. Numerical Modeling of Multiple Inclined Dense Jets Discharged from Moderately Spaced Ports. Water 2019, 11, 2077 .
AMA StyleXiaohui Yan, Abdolmajid Mohammadian, Yan. Numerical Modeling of Multiple Inclined Dense Jets Discharged from Moderately Spaced Ports. Water. 2019; 11 (10):2077.
Chicago/Turabian StyleXiaohui Yan; Abdolmajid Mohammadian; Yan. 2019. "Numerical Modeling of Multiple Inclined Dense Jets Discharged from Moderately Spaced Ports." Water 11, no. 10: 2077.