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This study presents the development of a thermal energy storing cementitious composite that incorporates phase change material (PCM) microencapsulated in biosourced polymer shell (m-PCM). The biodegradability of the encapsulated PCM was assessed using Nuclear Magnetic Resonance (NMR), which confirmed the high biodegradability of the m-PCM shell under specific environmental conditions. To examine the thermophysical properties of the m-PCM, Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA) were performed. The DSC results revealed exothermic enthalpies of 84.7 J/g and 140.2 J/g, with associated peak temperatures of − 3.2 °C and − 22.9 °C, respectively. Subsequently, the m-PCM was incorporated into cement-based mortar at proportions of 5%, 10%, and 15% by weight of binder. Uniaxial compression tests were conducted to evaluate the effect of the m-PCM on the mechanical properties of the mortar. The results indicated a significant decrease in mechanical strength upon incorporating the m-PCM. However, this reduction in strength was mitigated by the addition of silica fume (SF) and multiwalled carbon nanotubes (MWCNTs) in combination. Furthermore, a thermal cycling test was performed to examine the behavior of the nanomodified m-PCM incorporated mortar under varying ambient conditions. The results showed that the addition of MWCNTs improved both the mechanical performance and thermal performance of the composite.

Soil is a heterogeneous medium, the characteristics that determine soil slope stability are highly variable, making the analysis a difficult task. The present research approach is switching from deterministic to probabilistic in order to account for the variability in soil properties. This research presents the use of three soft-computing techniques to evaluate reinforced soil slope reliability based on slope stability: Genetic Algorithm based Adaptive Network based Fuzzy Inference System (GA-ANFIS), Random Forests Classifier (RFC), and Group Method of Data Handling (GMDH). Shear strength parameters c (cohesion), ϕ (angle of shearing resistance) and ϒ (unit weight) are used as input variables, while Factor of Safety of Reinforced Soil Slope (F) is used as an output variable to determine the stability of a soil slope of a certain height. The Models were also evaluated using various assessment parameters and GA-ANFIS outperformed having some testing outputs as NS= 0.997, RMSE= 0.017, VAF= 99.731 %, Bias Factor= 1.002, PI= 1.998, R2 = 0.997, GPI= 6.6E-08, U95 = 0.627, tstat= 0.247 and β = 1.543. The GA-ANFIS model outperformed the GMDH and RFC models, according to the findings of the analyses using Taylor diagram and ROC curve. As a result, the GA-ANFIS model can be utilized as a reliable soft computing technique to analyze reinforced soil slope stability.

In this study, a new empirical equation was established to predict the sedimentation volume resulting from the construction of a multi-purpose weir or low-head dam using experimental approaches. Applying the 1-D numerical model (STAFF), which is based on Exner’s equation, 2545 cases were simulated and laboratory experiments were conducted with various sediment particle sizes, channel slopes, inlet discharge, and outlet water elevation. Short-term predictions were conducted through laboratory experiments with movable bed, and the results indicated that dimensionless unit stream power and the Shields parameter exhibited the most significant correlation with dimensionless deposition volume. In particular, we analyzed the phenomenon in which the backwater effect and reservoir delta. Using a multiple regression approach, the developed empirical equation was validated for predicting sedimentation in the upstream reservoir of the weir.

Because of multifunctional weirs installed as part of large river regulation works in Korea, water quality problems have arisen from environmental changes in tandem with decreased flow rates. However, there has been limited research into the green algae removal effect, water quality improvement in congested waters, dam and weir operations, and consequential riverbed changes. Studies regarding outflow in a basin, the application and development of sediment load output analysis methods, feasibility of related dam operations, and riverbed patterns have been separately performed. However, basins and rivers should be analyzed by an integrated method instead of an individual one. Therefore, in the present study, the effect of congestion on a river connected to a dam/weir and estuary bank was analyzed based on climate change scenarios HadGEM3-RA RCP 4.5 and 8.5, with the aim of integrating individual studies using watershed and river models. Flow was controlled by dam- and weir-related discharge simulations. Variations in the riverbed caused by the transfer of suspended load in the downstream region were analyzed for both long and short durations. The results of this analysis suggest that given future climate change scenarios, the width of the river and riverbed variations in the riverbed are expected to rise. HIGHLIGHTS Impact of long-term geometric variation in rivers.; Analysis of climate change scenarios.; Integrate watershed and river.; Variations in the riverbed for both long and short durations.; Analysis of both watershed runoff and sediment transport in a river.;

The main goal of this study was comparing the performance of an open-source code OpenFOAM and a commercial software Ansys Fluent in simulating the turbulent flow through a scour hole developed in a sand bed channel, which helps to give a hint in choosing the appropriate calculating tool. Both models were set with the same mesh and as similar as possible numerical settings, with RANS turbulence modeling, applying the k-ωSST model, in transient simulations. The results of flow pattern, velocity, and turbulence properties were collected and compared with laboratory experimental data. The analyzed results showed that, although both of the two models cannot perfectly reproduce the values from a laboratory experiment, they can quite well capture the flow in scour hole near the wall, with a bit higher performance coming from the OpenFOAM model application.

Water scarcity can mean scarcity in availability due to physical shortage, or scarcity in access due to the failure of institutions to ensure a continuously regular supply or due to a lack of adequate infrastructure. Water scarcity will be exacerbated as rapidly growing urban areas place heavy pressure on water resources. To solve these problems, various solutions have been applied, but a fundamental solution has not been applied. Recently, a researched and developed infiltration rainwater drainage (IRD) system is being applied with consideration of its applicability. In this study, features of surface runoff and infiltration according to various flow patterns were analyzed using a three-dimensional CFD (Computational Fluid Dynamics) model for calculating water flow in the IRD system. To estimate the optimal setup, a permeability test and scaled model simulation were performed. The runoff characteristics of the IRD system with respect to rainfall intensity and duration were analyzed with dimensionless variables. With the prototype model, the drainage characteristics of the IRD system were analyzed over time using the hydrological curves. From the simulated results, it was found that the IRD system analyzed in this study was appropriate in the field by comparative analysis with the existing system based on peak runoff, internal storage, and lag time. Therefore, by applying the IRD system in the future, it is expected that the IRD has benefits, such as delayed lag time, surface runoff decrease, and an attenuation of the peak runoff.

Flow simulation over a dune requires the proper input of roughness coefficients. This study analyzed a numerical simulation of open-channel turbulent flow over two-dimensional fixed dunes to reveal the effect of roughness on the dune bottom, and to determine the optimized combination of the turbulence scheme and the roughness height formula. The most appropriate roughness values and turbulence models were applied using Reynolds-averaged Navier–Stokes models. Seven methods were chosen to estimate the bed roughness properties at the inlet boundary section. The results of all cases calculated with the OpenFOAM toolbox were compared with laboratory experimental data for model validation. The performances of all bed roughness variations were evaluated according to the stream-wise and depth-wise directions with nondimensional values. Consequently, it was revealed that the combination of bottom roughness length scale at the inlet boundary and the k-ω shear-stress transport (SST) model was the most suitable for the flow separation zone and turbulent properties near the channel bottom.

Local scour at the downstream of the river bed protection is one of the most important parameters for the design criteria and sustainable management of the hydraulic structures. Previously, various researches on its process in the equilibrium state have been suggested with experimental and numerical approaches. In this study, relatively long-term laboratory experiments of local scouring at the downstream of fixed bed in an open channel were conducted with mono-granular sediment bed and analyzed about maximum scour depth and its temporal development. In particular, we conducted experiments with relatively low Froude number (less than 0.5) and their duration of tests was exceeded over 700 hours. We modified the relationship between the dimensionless time and length scales of the maximum scour depth of the local scour hole based on the turbulent shear layer thickness. A new functional relationship between dominant factors and the maximum scour depth in the equilibrium state were suggested and compared with previously suggested formula. Also, from the results by nonlinear regression, Froude number was founded as a dominant factor on the prediction of equilibrium maximum scour depth.

Local scour occurs around hydraulic structures such as piers, bed protections, and dikes. In this study, the turbulent flow around a scour hole downstream of a fixed bed protection was investigated. Numerical modeling with OpenFOAM was applied to compute the flow velocity and turbulent kinetic energy with respect to flow conditions by changing water depth. A proper computational grid size and time step for simulations are suggested. Three typical turbulent models, k − ε , k − ω , and k − ω S S T , were considered for simulating the flow around a scour hole. The performances of the three models were evaluated by comparing them with numerical and laboratory experimental results. Mean flow velocity profiles computed by the three turbulent schemes are generally in good agreement with laboratory measurements. However, k − ω has a limitation in simulating reversal flow in the scour hole, and the k − ε model does not predict turbulent kinetic energy well near the bottom. Thus, this study found that the most suitable turbulent model for simulating flow around a scour hole downstream of a fixed bed protection is the k − ω S S T model.

Currently, the waterfront facility was constructed in New Songdo City, South Korea. It has the various water leisure areas and especially an artificial urban canal with filtered seawater by re-circulating flow system. However, due to excessive amount of nutrients from seawater combined with complicated geometry, it is highly vulnerable to deterioration of water quality. In this study, flow characteristics and pollutant transport were analyzed with comprehensive numerical models, MIKE 3 FM and ECO-lab. Based on these numerical results, notable sampling points were selected for field measurements and comparison between modeling and measured results were conducted. In addition, the integrated water quality evaluation index, Water Quality Index was applied to analyze various water quality issues. We also set up scenarios to control the two kinds of water quality factors, dissolved oxygen (DO), and total phosphorus (TP). As a result, the effect of 20% reduction of TP was less than 10% and it was almost ineffective for a year but it was reduced by up to 40% in case of scenario which DO is increased by 20%. Therefore, it was recommended to control the DO concentration, usually by applying re-aeration facility, rather than TP in artificial urban canal with seawater. [ABSTRACT FROM AUTHOR]

The Soil andWater Assessment Tool 2012 (SWAT2012) offers four sediment routing methods as optional alternatives to the default simplified Bagnold method. Previous studies compared only one of these alternative sediment routing methods with the default method. The proposed study evaluated the impacts of all four alternative sediment transport methods on sediment predictions: the modified Bagnold equation, the Kodoatie equation, the Molinas and Wu equation, and the Yang equation. The Arroyo Colorado Watershed, Texas, USA, was first calibrated for daily flow. The sediment parameters were then calibrated to monthly sediment loads, using each of the four sediment routing equations. An automatic calibration tool--Integrated Parameter Estimation and Uncertainty Analysis Tool (IPEAT)--was used to fit model parameters. The four sediment routing equations yielded substantially different sediment sources and sinks. The Yang equation performed best, followed by Kodoatie, Bagnold, and Molinas and Wu equations, according to greater model goodness-of-fit (represented by higher Nash-Sutcliffe Efficiency coefficient and percent bias closer to 0) as well as lower model uncertainty (represented by inclusion of observed data within 95% confidence interval). Since the default method (Bagnold) does not guarantee the best results, modelers should carefully evaluate the selection of alternative methods before conducting relevant studies or engineering projects. [ABSTRACT FROM AUTHOR]