Hydraulic Analysis Research Articles

Flood Modeling for the Cisanggarung River in the Cilengkrang Village using the HEC-RAS Software

This research aims to model the flood overflow of the Cisanggarung River in Cilengkrang Village using HEC-RAS software. A quantitative method was used with a focus on hydrological and hydraulic analysis. The hydrological analysis includes rainfall calculation, Thiessen Polygon method, frequency analysis, rainfall intensity, Nakayasu method, and planned discharge calculation. Hydraulic analysis was performed using HEC-RAS to model flood overflow. The research results show that the annual rainfall in the study area varies significantly, with the highest recorded rainfall of 1290 mm in 2020. The planned discharge of the Cisanggarung River was calculated at 2137 m³/second. HEC-RAS modeling revealed that the river cross-section capacity is inadequate to contain flood discharge, especially in the upper part near the settlement. Flood distribution occurs at several points along the river with varying levels of elevation. This research provides important information for flood disaster mitigation planning in the Cilengkrang Village area and its surroundings and demonstrates the effectiveness of using HEC-RAS in river flood modeling.

Core design and neutronics analysis of lead liquid metal-based heat pipe cooled reactor for undersea purpose

Abstract Various heat pipe-cooled reactors have been conceptualized and designed in recent years, ranging from kilowatts to megawatts, suitable for remote and extreme environments. However, existing designs employ monolith cores, which are saddled with heat transfer deteriorations due to thermal expansion and subsequent deformations are some of the key challenges facing monolith heat pipe reactors. Addressing this, a novel 300 kW heat pipe has been designed by introducing lead liquid instead of the monolith. A comprehensive Monte Carlo neutronics analysis of the designed core has been conducted including its thermal analysis. The core design comes with the following parameters: fresh core excess reactivity of 2.9914 $ that can support a 10-year life cycle, and a negative temperature coefficient of −0.1648 pcm/K. The axial and radial peak power factors at critical states were calculated to be 1.67 and 1.35 respectively. Preliminary thermal hydraulics analysis shows maximum temperatures of 1044 K under normal operation and worst-case accident scenarios (3 heat-pipe failures) of 1,149.9 K. These temperatures are lower than the melting point of uranium nitride fuel and lower than the possible heat pipe boiling failure limit at 1,300 K. Thus, the possibility of fuel melting/heat pipe boiling accidents is avoided. A hypothetical criticality accident was simulated, assuming the core was flooded with water, leading to an increased fission rate. However, the implementation of three emergency rods in the core ensures the subcritical of the reactor.

Vibration response analysis of hydraulic pipeline based on finite element method

The oil pipeline is a critical component that influences the vibration and noise levels of the hydraulic system. Inadequate design may result in resonance or leakage issues, rendering it susceptible to external vibration excitation. To enhance the reliability of the hydraulic pipeline, simulations and analyses were conducted on its modal, harmonic response, and fatigue characteristics. Based on the results of harmonic response analysis and strength analysis, an effective reinforcement scheme was proposed and validated. By inputting the acceleration load to the pipeline system for frequency response analysis, the influence of different excitation forces on the pipeline stress can be determined. The findings indicate that pipeline vibration primarily occurs in the outlet pipe of the transmission, with significant stress and vibration displacement observed at the thermostat valve support. Following structural improvements, there was a notable reduction in stress levels at the transmission outlet pipe, along with a shift in maximum stress position due to additional support. This enhancement has improved both structural stiffness of the outlet pipe and overall stability of the pipeline system.

Nature-Based Solutions for Flood Mitigation in Metropolitan Areas

Flooding is a globally common problem in metropolitan areas including Jakarta, Indonesia. The increased intensity and frequency of rainfall caused by climate change and rapid urbanization have raised the risk of flooding in urban areas. One solution is to implement polders to mitigate flooding in coastal metropolitan areas. Regrettably, the current polder system is inadequate for managing flooding due to rapid land-use changes and regional expansion. This study analyzes flood control in the Jakarta region using the East Sunter Polder System, which experienced flooding in both 1990 and 2020 despite the implementation of the polder system. The polder system, consisting of four catchment areas—Petukangan, KBN 1/Sukapura, KBN 2, and Kebantenan—faces drainage challenges exacerbated by rainfall. To mitigate flood risks, Nature-Based Solutions (NBSs) have been implemented, including retention ponds and long storage systems. Hydrological and hydraulic analyses were conducted using HEC-HMS and HEC-RAS, and ArcGIS was employed for floodplain integration. This study underscores the significance of incorporating NBSs in urban flood management, demonstrating how they enhance resilience and mitigate flood risks. By integrating NBSs into the urban planning framework, the findings suggest that flood risk management can be significantly improved, leading to better preparation and long-term sustainability for managing natural hazards.

Coupled simulation for pin-wise reactor core analysis using subchannel analysis code CUPID and fuel performance code GIFT

Recent efforts to develop high-fidelity, multi-physics safety analysis methodologies aim to assess realistic safety margins. However, they remain conservative using initial conditions based on the hot rod with maximum power for the whole reactor core. This study presents the development and verification of a coupled code for pin-wise reactor core analysis using the subchannel analysis code CUPID and the fuel performance code GIFT. The goal was to generate accurate pin-wise fuel rod conditions during normal operation for safety analysis. CUPID was applied for thermal–hydraulic analysis considering fuel behavior, and GIFT was extended to multiple fuel rods. The coupled code was verified for a single assembly to examine subchannel geometry deformation, followed by a practical simulation for a quarter reactor core during the first cycle. Key parameters for safety analysis were examined, revealing that maximum stored energy occurred in a specific fuel rod rather than the hot rod with maximum power.

Normalization of Suak Ujong Kalak estuary as a flood reduction effort for Meulaboh city

Abstract Meulaboh City frequently experiences flooding, with runoff flowing into the Suak Ujong Kalak Estuary, a natural outlet for the city’s drainage system. Currently, the estuary is unable to effectively accommodate the runoff, exacerbating the flood risk. This study aims to evaluate the existing condition of the Suak Ujong Kalak Estuary and propose a normalization plan to improve flood control. The research employs a descriptive-quantitative methodology, involving field surveys, data collection, and hydrological and hydraulic analyses. The hydrological analysis includes rainfall frequency analysis, chi-square testing, and rainfall intensity calculation using the Mononobe method. Flood discharge estimation is based on the Rational method for a 25-year return period. Hydraulic analysis is conducted using HEC-RAS 6.3.1 software. The results show that the estuary receives an inflow of 79.33 m3/second, which exceeds its current capacity. Hydraulic analysis reveals that the estuary cannot accommodate the discharge, causing overflow with an average height of 0.6 meters and a storage capacity of 40,798.43 m3. To address this, the study recommends a normalization effort, involving excavation with an average depth of 1 meter, to improve the estuary’s capacity and reduce flooding in Meulaboh City.

Hydraulic dissipation analysis in reversible pump with a novel double-bend impeller for small pumped hydro storage based on entropy generation theory

Hydraulic dissipation analysis in reversible pump with a novel double-bend impeller for small pumped hydro storage based on entropy generation theory

Enhanced support vector machine-based moving regression strategy for response prediction and reliability estimation of complex structure

For predicting response property and estimating reliability level of complex structure, enhanced support vector machine-based moving regression (MR-ESVM) strategy is proposed based on support vector machine (SVM), heuristic algorithm and moving least square (MLS) technique. Under this strategy, we develop four different SVM models including SVM-based moving regression (MR-SVM), SVM-based improved moving regression (IMR-SVM), improved SVM-based moving regression (MR-ISVM) and bi-optimized SVM-based moving regression (BiOMR-SVM) methods. In these developed MR-ESVM approaches, the MR-SVM method is explored by introducing the MLS technique into the SVM model; the IMR-SVM method is discussed by fusing the MR-SVM method and artificial rabbits optimization (ARO), and the ARO is used to search the optimal radius of compact region; the MR-ISVM method is raised by integrating the ARO into the MR-SVM, and the ARO is applied to find the optimal values in the SVM model; The BiOMR-SVM method is emerged by merging the IMR-SVM and MR-ISVM methods. To verify the effectiveness of these developed MR-ESVM strategies, a multivariate nonlinear function approximation is implemented to illustrate the advantages from the mathematics perspective, an aeroengine turbine blisk radial deformation reliability analysis and an aircraft hydraulic system low pressure reliability analysis are derived to demonstrate the applicability in engineering practice. The analytical results show that these four MR-ESVM approaches hold excellent merits in modeling features and simulation characteristics. The efforts of this work provide a novel idea for the response prediction of complex structure, and enrich the reliability estimation principle of surrogate models of complex structure.

Operating Reliability of In-Grid HTS Power Cables Based on Electromagnetic–Thermal–Hydraulic Analysis

Operating Reliability of In-Grid HTS Power Cables Based on Electromagnetic–Thermal–Hydraulic Analysis

Thermoeconomic Evaluation of the Triple Pressure-Swing Distillation Process

Objective: Investigate distillation as a separation process based on the difference in volatility of components, focusing on the separation of azeotropic mixtures using Pressure-Swing Distillation (PSD). The study was applied to the ternary mixture water-acetonitrile-isopropanol (Water-ACN-IPA). Theoretical Framework: Based on previous studies that demonstrated the feasibility of PSD for separating this mixture using three columns operating at different pressures. However, challenges related to high energy consumption persist due to system irreversibilities. Method: Hydraulic analysis of the columns is proposed, including the implementation of variable diameter and thermal integration as optimization strategies. Results and Discussion: Results show a 47.5% reduction in the total annual cost (TAC), demonstrating greater economic efficiency and process viability. Research Implications: The study contributes to improving energy efficiency in azeotropic separation processes using PSD, providing practical solutions to minimize costs and environmental impacts. Originality/Value: This work introduces technical innovations in azeotropic distillation using PSD, offering an economically optimized and viable approach for the chemical, petrochemical, and pharmaceutical industries.

Application of risk informed safety margin characterization to the analysis of a pressurized water reactor

The sequence Core Damage Frequency of a pressurized water reactor has been quantified in three initiating events that are Medium Break Loss of Coolant Accident, Small Break Loss of Coolant Accident and Steam Generator Tube Rupture, following a realistic methodology called risk informed safety margin characteristic. The surrogate plant analyzed in the study is a typical pressurized water reactor. The plant adopted two Westinghouse Three-Loop Pressurized Water Reactors with rated thermal power of 2,830 MWt. The phenomenon identification and ranking table is applied for uncertainty analysis. The mitigation actions as described in plant specific Probabilistic Risk Assessment include cooldown and depressurization, emergency cooldown and depressurization, high head safety injection, high head safety recirculation, low head safety recirculation and Refueling Water Storage Tank replenishment. These mitigation actions are analyzed by thermal hydraulic system analysis code RELAP5-3D to determine the successfulness of the actions. The uncertainties of input parameters of the plant conditions are included, and the time of mitigation action executed is treated as one of the input uncertainties. The results of realistic methodology show a decrease in Core Damage Frequency for all three analyzed events in comparison with conventional methodology. The differences between three initiating events are also discussed.

Transient analysis of megawatt-level space gas-cooled reactor coupled with He-Xe Brayton cycle system

The development of the aerospace industry and advancements in aerospace technology have created an urgent need for space power supply. A self-developed thermal hydraulic system analysis program is utilized to examine the transient response safety of gas-cooled reactors and investigate the performance of the coupled Brayton cycle overall system. The typical transient accident conditions were simulated, including positive reactivity insertion, turbine-alternator-compressor shaft speed drop, and loop coolant flow rate reduction. By considering cladding integrity as the safety criterion, it is determined that the reactor studied in this work has a safety margin of 0.152$ when introducing reactivity. The introduction of positive reactivity enhances reactor power output and heat generation. As more heat is carried away by He-Xe gas into the turbine, both operating temperature and heat transfer efficiency within the thermal cycle system are further improved. With an introduction of 0.13 % positive reactivity into the core, reactor thermal power can be stabilized at 110 % of its rated value while increasing system thermoelectric conversion efficiency by 2.7 %. During a continuous turbine-alternator-compressor shaft speed drop incident (from 100 % to 80 % rated speed), the total electrical power drops to 580 kWe along with reductions in temperature ratio and pressure ratio for both turbine and compressor. System cycle efficiency shows a positive correlation with turbine-alternator-compressor shaft speed within an appropriate range. In a sudden coolant flow rate drop incident, when the loop flow rate decreases to 60 % of its rated value, both reactor power and turbine-alternator-compressor shaft power decline significantly: the total electrical power drops from 1096 kWe to 216 kWe while the system’s cycle efficiency decreases from 32.1 % to 12.13 %. This work provides valuable insights into conceptual design considerations as well as safety assessment aspects pertaining to megawatt-class space.

Hydraulic performance analysis of new versus commercial nozzle design for pressurised porous media filters

AbstractRapid water filtration with pressurised porous media filters is extensively applied in drip irrigation systems. In double-chamber filters, the underdrains are fixed to the base of the inner plate to sustain the media above while draining water. Here, a new underdrain design intended to reduce the filter energy consumption is presented. The main difference with commercial underdrain units corresponds to the distribution of the slots, being in a horizontal plate to uniformise the flow trajectories inside the porous media. Both commercial and new underdrain designs have been tested in laboratory in both filtration and backwashing modes with three media types, two media heights, and superficial velocities ranging from 20 to 120 m h−1. In filtration mode, results indicate that the new design reduces the filter pressure drop by 31% at 60 m h−1 in comparison with the commercial one. The exploration with an analytical model that correctly reproduces the filter pressure drop, reveals that its value at 60 m h−1 is only 15% higher than the ideal scenario (uniform flow throughout the porous media bed). In backwashing mode, the pressure drop in comparison with the commercial design is reduced by 65% at 80 m h−1, while having the same trend for the bed expansion, which is also predicted by a simple analytical expression. Thus, the new underdrain design produces a more homogeneous fluidised regime than the commercial one at low-moderate superficial velocities.

Combining machine learning and physics modeling to determine the geostress of reservoirs in real-time

Real-time updating of geological properties in reservoirs through monitoring data is critical for optimizing hydraulic fracturing. In this work, the ML-Physics method, which inherits the advantages of machine learning (ML) and physical modeling, has been developed to determine the geological parameters with limited computational time, including far-field geostress, geostress in the vicinity of faults and rock material properties. The ML-Physics method consists of two stages: the preparation stage and the operation stage. During the preparation stage, which occurs before the in situ operation and is not constrained by computational time limitation, a surrogate artificial neural network (ANN) model is established. This ANN model captures the implicit relationship between geological parameters and monitoring data. During the operational stage, which is constrained by real-time requirements for the convenience of engineers in field work, inverse analysis with physical modeling and the surrogate ANN model is employed to determine geological parameters. In the context of ML-Physics method, the initial values of inverse iteration are chosen based on surrogate ANN results. The obtained geological parameters can be used for hydraulic fracturing analysis. This ML-Physics method demonstrates superior performance in terms of both accuracy and computational efficiency.

Flood Mapping using HEC-RAS and GIS: A Case Study of Palembang Watersheds

Flooding is a significant issue in Palembang City, affecting areas such as Gandus, Lambidaro, Boang, Sekanak, Bendung, Kidul, Buah, Juaro, Selinca, Nyiur, Aur, Sriguna, Kedukan, Keramasan, Kertapati and Jakabaring watershed. This research contributes to flood control measures by providing flood mapping and modelling for decision-makers and local authorities. The main objective of this paper is to perform a steady flow analysis to study the hydraulic characteristics of flow; velocity and water surface profile of the adjacent research areas. There are three processes involved in the data analysis: hydrological, hydraulic and spatial. The calculation of average rainfall is performed using the Isohyet method with the assistance of the IDW 3D Analyst tool in ArcGIS and the design discharge is calculated using the HSS Nakayasu method. The hydraulic analyses involve river morphology extraction using RAS Mapper tools in HEC-RAS. Steady flow simulations are conducted for normal water depth conditions and the highest tidal conditions. The simulation result is then reclassified and the flood location points are verified with observed data. For normal water depth conditions, the maximum water level in the Lambidaro watershed reaches 2,09 meters, which covers a flood area of 721,53 ha. Meanwhile, based on the highest tidal simulations, the maximum water level in the Selinca watershed reaches 3,21 meters, covering a flood area of 209,36 ha.

DeepPipe: A multi-stage knowledge-enhanced physics-informed neural network for hydraulic transient simulation of multi-product pipeline

In the chemical pipelining industry, owing to the high-pressure transportation process, an accurate hydraulic transient simulation tool plays a central role in preventing the slack line flow and overpressure from causing pipeline operation treacherous. Nevertheless, the current model-driven method often faces challenges in balancing computational efficiency with accuracy, and the existing data-driven models struggle to produce explainable results from the physics perspectives since insufficient theoretical principles are incorporated into the model training. Additionally, the existing physics-informed learning architecture fails to achieve a gradient-balanced training, resulting from the significant magnitude difference in outputs and multiple loss terms. Consequently, a Multi-Stage Knowledge-Enhanced Physics-Informed Neural Network (MS-KE-PINN) is proposed for the hydraulic transient simulation of multi-product pipelines. To enforce the neural network producing simulation results with high consistency to physical laws, the governing equations, boundary, and initial condition are incorporated into the training process for an efficient mesh-free simulation. Then, considering that the significant magnitude difference between outputs can easily lead to deficient performance in the gradient descent, the magnitude conversion on the outputs and the equivalent conversion of the governing equations are implemented to enhance the training effect of the neural network. Subsequently, to tackle the imbalanced gradient of multiple loss terms with fixed weights, a multi-stage hierarchical training strategy is designed to improve the approximation capacity of the neural network. Numerical simulation cases demonstrate a better approximation function of the proposed model than the state-of-art models, while the mean absolute percentage errors yielded by MS-KE-PINN are reduced by 77.4 %, 88.7 %, and 87.8 % in three simulation operation conditions for pressure prediction. Furthermore, experimental investigations from a real-world multi-product pipeline suggest that the proposed model can still draw accurate simulation results even under complex and dynamic hydraulic transient scenarios in practice, with root mean squared errors reduced by 94.8 % and 80 % than that of the physics-informed neural network. To this end, the proposed model can conduct accurate and effective hydraulic transient analysis, thus ensuring the safe operation of the pipeline.

Thermal hydraulic and material analysis of upgraded flat-type Graphite divertor mock-up for Pakistan Spherical Tokamak (PST)

The design of a divertor is critically dependent on managing power deposition, erosion effects, and plasma configuration. An upgraded double-null divertor configuration has been developed for the Pakistan Spherical Tokamak (PST), featuring graphite targets that are actively cooled and designed to withstand a peak heat flux of 0.3 MW/m² at a pressure of 0.1 MPa. This paper presents a comprehensive thermal-hydraulic and material analysis for the upgraded flat-type divertor mock-up system, covering aspects such as material surface heat load, peak temperature rise (∆T °C) on the mock-up, and surface temperature increase in the cooling channel. The analysis includes total deformation (mm) and equivalent strain for the inner vertical target (IVT), outer vertical target (OVT), and dome structure, along with material comparison. The recommended SST K-ω turbulence model is utilized in the pressure-based transient analysis, with an inlet velocity of 1.5 m s-1 and an inlet temperature of 16.8 °C. A comparative study of the material and thermal-hydraulic analyses was performed using CFD and RELAP5. The findings reveal that graphite is more suitable than tungsten for the PST's upgraded divertor system, demonstrating its effectiveness as the preferred surface material to address heat enhancement challenges in the PST.

PREDIKSI DAMPAK PERUBAHAN TATAGUNA LAHAN TERHADAP DEBIT LIMPASAN, STUDI KASUS: GEREJA RANCASARI

Flooding is one of the most frequent natural disasters in Indonesia. Based on data, as of 2024, there have been 137 cases of flooding incidents. One of the causes of flooding, particularly in urban areas, is due to land use change. This study examines the impact of land use changes on runoff discharge in a Church area in the Bandung City. Additionally, this study investigates the effect of the development of this area on flood water levels in the Riung channel, which serves as an outlet channel. In this study, modeling is conducted using the SWMM model. The study utilizes data from the BMKG Bandung and GPM satellite rainfall data from 2001 to 2022 for rainfall analysis. The results indicate that in the study area, the duration of extreme rainfall producing maximum discharge is rainfall lasting for 7 hours. As a result of the church development, runoff discharge increases by 26.3 – 34.4% across various return periods. For time to peak, there is no significant change in conditions before and after the area is developed. This is due to area is relatively small, resulting in a relatively shorter concentration time. Based on the hydraulic analysis, the Riung channel is still able to accommodate additional runoff generated due to development, leaving a freeboard height of 4.5 cm for a 10-year return period. However, based on observations, special attention is needed regarding the issue of sedimentation and trash, which often causes backflow in several segments of the trenches.Keywords:runoff, land use change, urban drainage, SWMM, Bandung

Engineering and Modeling of Water Flow via Computational Fluid Dynamics (CFD) and Modern Hydraulic Analysis Methods

The manuscripts presented in this Special Issue will both present engineering analyses of problems of contemporary importance in fluid mechanics and hydrodynamics and describe historical water systems and the technologies used to design and operate them by ancient Old and New World water engineers [...]

Field study on proactive pipe condition assessment using hydroacoustic noise

Condition assessment of water transmission pipelines is of important necessity for prioritizing rehabilitation and preventing catastrophic pipe failure. Hydraulic transient analysis has been investigated for three decades for this purpose and applied to many field studies. However, the significant pipe vibrations caused by the transient generation process and the limited energy and bandwidth of conventional discrete transient pressure waves (e.g., step and pulse waves) limit the accuracy and resolution of the analysis. This paper reports a pilot field study of noninvasive and nondestructive pipe condition assessment using small amplitude and persistent hydroacoustic noise instead of conventional large and discrete hydraulic transient waves. By opening a discharge valve installed at an existing access point, such as an air valve, on the field pipe, hydroacoustic noise was generated at the valve due to the turbulence of the discharge. The hydroacoustic noise was measured by pressure transducers at this access point as well as some other access points along the field pipe. A signal deconvolution process was then applied to the measured hydraulic pressures to transfer them to a compositional impulse response function (IRF), which is composed of IRFs of different pipe sections. A mathematical model was derived to interpret the anomaly-induced spikes on the deconvolution trace. A time-shifting process on the compositional IRFs was proposed to find the locations with pipe condition changes from a specific direction of the pipe. The field study has shown that small-amplitude persistent hydroacoustic noise can replace conventional large hydraulic transient waves for pipe condition assessment.