Maximum Water Velocity Research Articles

Research on the technical improvement of the turbine runner of a power station based on improving stability

AbstractIn view of problems such as the narrow efficiency area, large hydraulic vibration area, pressure pulsation, and serious sediment wear of turbines at the Futang hydropower station, the technical transformation of turbine runners was carried out by modifying the blade shape and increasing the blade thickness, and a combination of numerical simulations based on shear stress transport k–ω turbulence model and tests was adopted to improve the operational stability of power station units. Calculation and testing demonstrate an enlargement of the high‐efficiency zone. Specifically, the optimal efficiency of the runner increases by 0.37%, while the rated efficiency rises by 0.19%. Significant reductions are observed in pressure pulsation within the draft tube and vaneless area decrease of approximately 50%. There is a high‐frequency pressure pulsation in the vaneless zone and the runner under low‐load conditions, and the influence of dynamic and static interference gradually weakens with the increase of opening. The draft tube is prone to eccentric vortex bands under partial working conditions, which causes the unit to be affected by low‐frequency pulsation. This optimization also leads to a notable decrease in runner blade wear, with the maximum sand and water velocity reduced from 45 to 40 m/s, resulting in a 30% reduction in sand wear. Moreover, there is a substantial enhancement in the runner's stiffness, with the thickness of the blade near the high stress area of the upper crown and lower ring increasing by over 50%, and the weight of each individual blade increasing by more than 50%. These research findings validate that modifying the runner blade effectively improves flow patterns, reduces eddy current generation, minimizes pressure pulsation, widens the high‐efficiency zone, decreases wear, and enhances the operational stability of the unit. The technical transformation method and research results of this study have important guiding significance for similar technical transformation of other power stations

Tsunami propagation and flooding maps: An application for the Island of Lampedusa, Sicily Channel, Italy

AbstractThe Mediterranean coastlines are densely populated zones which host key socio‐economic and commercial activities. For this reason, coastal areas are vulnerable sites in case of natural disasters as tsunamis that can strike coasts causing widespread damage to the population and facilities. For these reasons, several studies were performed over the last decade to study the impact of tsunami waves on the coasts. This research assessed the inundation risk due to a tsunami wave which can hit the southeastern coast of Lampedusa Island. The coastal low‐lying geomorphological setting of the southeastern part of the island led to significant socio‐economic growth, but Lampedusa falls within the Mediterranean Sea, a high‐tsunamigenic area, therefore, the need to investigate tsunami propagation and coastal flooding of this sensitive site emerged. For this scope, a calculation chain model was implemented incorporating three steps: the DELFT‐3D software for earthquake effects modelling, MIKE 21 Flow Model FM for nearshore propagation and HEC‐RAS for onshore tsunami inundation modelling. The simulations illustrate the impact of three tsunami scenarios with different magnitudes (Mw 8.5, 7.5, 6.5) generated by hypothetical earthquakes in the Hellenic Arc. In the Mw 8.5 magnitude scenario, significant flooding occurs in the harbour region, with maximum water depths reaching approximately 3.5 m. The maximum water velocity in this scenario reaches about 15 m/s in the eastern portion, adjacent to cliffs impacted by the tsunami wave. In contrast, the Mw 7.5 magnitude scenario demonstrates reduced flooded areas, with the cliffs containing the waves and preventing further flooding. Water depths and velocities in the Mw 7.5 scenario remain minimal. Changes in both propagation and flooding are not significant between scenarios Mw 7.5 and Mw 6.5. This methodology can be employed for more accurate tsunami wave simulations not only in the Mediterranean region but also in various case studies.

Swimming Performance Assessments of Fish Species of Greatest Conservation Need to Inform Future Stream Crossing Designs in Texas

Conventional structures associated with stream crossings such as bridges and culverts can lead to zones of high-velocity water flow that impede fish passage. Such obstacles are likely to harm native fish populations by impacting migrations critical to their life history strategies, causing habitat fragmentation and extirpation, thereby limiting population growth and distribution. Due to the high rates of human population growth and development occurring in Texas, this is an issue of particular concern for fish designated as species of greatest conservation need (SGCN). This project focused on four SGCN fishes native to the Edwards Plateau Ecoregion, namely the Guadalupe Bass, Guadalupe Roundnose Minnow, Guadalupe Darter, and Plateau Shiner, at both adult (all species) and juvenile (Guadalupe Bass only) life stages. Our primary aim was to aid in the design of future culverts associated with stream crossings (or the modification of existing culverts) so that the water velocities through these structures do not exceed the swimming capacities of our target SGCN fishes. To this end, we assessed their maximum sustained swimming speeds (Ucrit) under a typical range of Edwards Plateau stream temperatures (15, 22.5, and 30 °C) to be used in site-specific calculations of the maximum allowable culvert water velocities (Vf). A secondary objective was to collect physiological endpoints of relevance to the overall swimming performance including the maximum burst swimming speeds (Umax), metabolic rate measurements (i.e., standard metabolic rate (SMR), maximum metabolic rate (MMR), and aerobic scope (AS)), cost of transport (COT), and optimal swimming speed (Uopt). Temperature-related effects were observed that can be used to inform site-specific culvert designs. In general, the highest Ucrit values for the tested species were near, or possibly between, 22.5 and 30 °C, while Umax stayed relatively consistent among treatments.

Variables influencing stream‐type juvenile Chinook Salmon density within floodplain habitat in the Skagit River basin, Washington

AbstractObjectiveDespite decades of restoration work, Chinook Salmon Oncorhynchus tshawytscha in the Pacific Northwest remain under the protection of the U.S. Endangered Species Act (ESA). Chinook Salmon in the Skagit River basin play a vital role in the abundance and recovery of the Puget Sound Chinook Salmon Evolutionarily Significant Unit, which is currently listed as threatened under the ESA. The stream‐type juvenile (STJ) life history pattern of Chinook Salmon in the Skagit River has higher ocean survival to the adult stage (i.e., productivity) than that of parr or fry out‐migrants, and improvement in STJ Chinook Salmon habitat could increase abundance and diversity in the Skagit River basin. Our objective was to provide recommended ranges of variables shown to influence habitat selection in floodplains by STJ Chinook Salmon.MethodsUsing field observations from 70 sites within the Skagit River basin, we developed generalized linear mixed‐effects models across three seasons in floodplain habitats to correlate variable ranges with densities of STJ Chinook Salmon.ResultModel accuracy varied by season (summer: R2 = 0.24; winter: R2 = 0.56; spring: R2 = 0.54), and significant parameters included velocity, substrate, depth range, and distance to the closest connection with the main stem. Additional significant factors included wood cover, maximum water temperature, velocity range, and interaction of the ranges of velocity and depth. Recommended ranges for habitat variables associated with the highest densities of STJ Chinook Salmon include depths of 40–68 cm, velocities of 0.06–0.33 m/s, substrate sizes of 3–36 mm, and distances of 33–119 m to the main‐stem connection. Water temperatures associated with high juvenile densities varied by season (winter: 4–6°C; summer: 9–14°C).ConclusionOur recommended ranges for habitat variables can be used to refine designs for river restoration projects intended to improve habitat for juvenile Chinook Salmon and other salmonids in the Pacific Northwest.

Open channel velocity field investigation for hydrokinetic power generation

The paper presents an experimental study of a velocity field in an open channel. The study of water flow in an open channel is complicated due to the influence of various factors and different variables. Some of the variables affecting the flow parameters include the height of the water column, the width of the channel, the length of the channel, the slope of the channel, and the conditions of the channel bed. The investigated open channel is used for experimental research of kinetic turbines, and the flow speed in the channel is in the range of 0.1-0.3 m/s. The low velocity values in the channel are driven by the operation of the kinetic water turbines in real-world conditions. When describing the test channel, the influence of several boundary conditions has been taken into account, such as protrusions between the measurement sections, the water level, and disturbing effects. Results for the velocity fields determined in five sections of the test open channel are given. A turbine and an electromagnetic probe were used for the experiments. A comparison between the results obtained with the two measuring instruments under the same flow conditions in the test channel is made. The results for the velocity variation in the test sections for the maximum velocity in the channel are presented. At this maximum water velocity, the test channel maintains a water level of approximately 150 mm. The experimental data is also illustrated graphically, along with the velocity fluctuations along the channel centreline. The results obtained provide an idea of the expected velocity fields in the measurement open channel and the relative magnitude of the fluctuations in the different measurement sections.

Efficiency of cavity dissolution in rock salt by water submerged jets

To create cavities when dissolving rock salt, it is most expedient to supply the solvent through the nozzles of a perforated pipe in the form of submerged jets. This article examines the physical dissolution of a cavity with water from a stationary nozzle with a diameter of 0.004 m at two constant velocities at the nozzle cross-section. The efficiency of cavity dissolution, which has an almost cylindrical shape with a semi-cylindrical bottom, was analyzed at a nozzle cross-section speed of 8.85 m/s. The obtained results are explained on the basis of the fact that the formed cavity is a short dead-end channel where longitudinal compression acts. The flow in such a channel is caused by the back pressure exerted by its end. And the back pressure, in turn, hinders the development of the jet that flows out of the stationary nozzle, limiting its range. The cessation of significant expansion of the jet is indirectly confirmed by the use of an empirical formula for the distribution of the maximum water velocity along the axis of the jet. Its value at the end of the section of the most intense dissolution of the cavity becomes 8.85 times smaller compared to the speed at the nozzle cross-section. The boundaries of the area of the most intense dissolution of the cavity are determined by the relationship between the depth of the cavity, the diameter of the nozzle, the velocity at its cross-section, and the time of dissolution, which can be used to model the dissolution of cavities at different values of the velocity at the cross-section of the nozzle at its constant diameter. It was found that the relationship between the radius and depth of the cavity is linear. The angle between the boundary of the cavity size change and the axis of the nozzle is 20°23'. These results show that the dissolution of cavities is effective in a limited range of their dissolution time, the limits of which depend on the velocity of the solvent at the nozzle section. To confirm the obtained results, it is necessary to investigate the geometric characteristics of the cavities for other values of the nozzle diameters.

Numerical study of the effect of a V‐shaped weir on turbulence characteristics and velocity in V‐weir fishways

AbstractFishways are used to allow fish to migrate around water infrastructure, whether movements are in the upstream or downstream direction. Hydrodynamic conditions within various fishways, including turbulence levels, are important for successful fish passage. A numerical hydrodynamic study was conducted for V‐weir fishways, which assist species migrating upstream. The variables investigated included, fishway slopes of 4%, 7%, and 10%, relative spacing between weirs of 1.3, 2.6, and 4 (D/L, ratio of distance between weirs to pool width), and weir angles of 22.5°, 40°, and 60°. Turbulence characteristics, including turbulent kinetic energy (TKE), Reynolds shear stress (RSS), turbulent intensity (TI), turbulent dissipation (TD), as well as maximum water velocity, were examined by CFD (computational fluid dynamics) simulation using a re‐normalized group or RNG turbulence model. The CFD was calibrated with flow measurements made in a physical model of the V‐weir fishway in laboratory control experiments. Based on inferences from fish passage literature, the results showed that, in the range of parameters studied, a weir angle of 22.5°, a slope of 10% and relative spacing between weirs of 1.3 and 2.6 were assessed as offering the best potential performance for several species and sizes of fish, while the latter has lower cost as it requires fewer weirs. The V‐weir fishway may be adaptable for smaller fish.

Assessment of and Solutions to the Stormwater Management System of Auburn University Campus in Auburn, Alabama

Stormwater management needs attention as it causes surface flooding and pollution of nearby waterbodies. Parkerson Mill Creek in Auburn University, which gets polluted through surface runoff, is an example of this. In this study, a Personal Computer Stormwater Management Model (PCSWMM) was used to determine the susceptibility of the existing stormwater network to flooding on the Auburn University campus. Maximum water velocity mapping was used to identify areas associated with 3 categories of velocity (high, medium, and low) to find areas of potential erosion. Among the various sustainable stormwater management initiatives, it was found through a literature review that bioretention cells had the greatest potential to improve stormwater quality by screening pollutants from runoff water as well as minimizing erosion by reducing surface water velocity. Suitability analysis for bioretention cells identified 8 areas on the campus where bioretention cell could be installed for the most effective stormwater management. This study highlights the usability of PCSWMM models and techniques in increasing the efficiency of the stormwater system in any locality.

PTAD: A web-based climate service for building design adaptation

Projections Tool for Architectural Design (PTAD) is a web-based climate service product available at www.ptad.mju.ac.th. Targeted at building owners and designers, it is intended to support these decision makers in building design to reduce the impacts of climate change. This study presents the technical environment of PTAD and provides a conceptual basis for linking academic information on climate change to building-related data with the cooperation of the relevant authorities. The PTAD development concept was divided into three parts: climate change impact assessment in small areas (i.e., at a construction site scale), building damage analysis of the impacts, and climate-resilient recommendations for building design. Tools such as GIS, HEC-RAS, and ERDAS and the existing outputs of regional climate models were used as the baseline data for analyzing the impacts that may occur at the study site. The impacts in small areas and design strategies to reduce the potential damage were analyzed with the Delphi technique using existing standards and guidelines. A 3-tier architecture was employed for the production and development environments by modularizing the user interface, service object, and data storage layers. The impact data values, namely, the highest annual surface temperatures and flood characteristics, including the maximum flood level, flood duration, and water velocity from 1998 to 2047, were displayed as markers on the satellite maps, tables, and figures. The impacts can be linked to architectural design guidelines to help design buildings that mitigate some of the impacts of climate change.

Computational Fluid Dynamics Analysis of Gravitational Filter Based on Origami Concept (G-Filtro) Acted as Water Filtration Device in Water Tank

Water is the most demanding resource in the world especially in the era of the rapid growth of population and development. Therefore, delivering good quality water to consumers is important for their security of lives. Gravitational Filter Based on Origami Concept (G-Filtro) is a water filtration device that will be placed in a water tank at the residential area before people consumed it for everyday used. The specialty of this device, it does not necessarily attach to any power source. The objective of this project is to design and develop 3D G-Filtro using 3D CAD software and CFD analysis is used to determine the efficiency of the G-Filtro by simulating and model the pressure, velocity and streamline. Based on the result, the maximum water velocity for simulation without the filter is 0.266 m/s and the maximum velocity for first and second designed filter are 0.254 m/s and 0.243 m/s respectively. From the CFD simulation, the G-Filtro can remove the contaminants in water tank efficiently. Hence, it is proven that G-Filtro can be added as a new water filtration device.

Swimming capability of zebrafish is governed by water temperature, caudal fin length and genetic background

Several zebrafish strains such as AB, Tübingen (TU), Wild India Kolkata (WIK) and Tupfel long fin (TL) have been established for genetic study. Each strain has its morphological and behavioral traits. Motor traits, however, have not been explored in zebrafish strains. We here applied a treadmill for fish (swimmill) and measured swimming capability of adult zebrafish by critical swimming speed, which is the maximum water velocity in which fish can keep swimming. First, we confirmed that swimming capability does not vary between female and male. Second, we found that the appropriate water temperature for swimming was between 16 and 30 °C. Third, our fin clip experiments using long-finned zebrafish revealed that they can exhibit high swimming capability when the caudal fin length was set between 3 and 10 mm, implying that long-finned zebrafish are unfavorable for fast swimming. Finally, we compared swimming capability of several zebrafish strains and demonstrated that WIK fish was significantly less capable of swimming despite that they have short caudal fin (~9 mm). The offspring of WIK fish were less capable of swimming, while hybrids of WIK and TU showed high swimming performance comparable to TU. Thus, lower swimming capability of WIK strain is inheritable as a motor trait.

A Classification Method for Fish Swimming Behaviors under Incremental Water Velocity for Fishway Hydraulic Design

In fishway design, the combination of fish swimming behaviors and suitable fishway hydraulic characteristics increases the fish passage efficiency. In this study, the most representative grass carp among the “four major Chinese carps” was selected. Under conditions similar to the time period for feeding migration, juvenile grass carps were targeted to study the swimming characteristic indicators (i.e., critical and burst swimming speeds) and swimming behaviors that were closely associated with fishway hydraulic design using the incremental water velocity method in a homemade test water tank. (1) The study results reveal that both the absolute critical (Ucrit) and burst (Uburst) swimming speeds increased linearly with increasing body length and both the relative critical (U’crit) and burst (U’burst) swimming speeds decreased linearly with increasing body length. There existed a quantitative relationship between Uburst and Ucrit, which could facilitate the fishway hydraulic design. (2) This study analyzed the effects of water velocity changes on fish swimming behaviors and proposed a classification method for four fish swimming behaviors—swimming freely, staying, dashing at a long distance, and dashing at a short distance—of tested fish during the process of adapting to water velocity changes interspersed with one another. The entire swimming process under the incremental water velocity was divided into four stages. (3) This study suggests that the maximum water velocity of the mainstream in a fishway using grass carp as the major passage fish should not exceed 52–60% Uburst at stage 1. For the high-water velocity areas of a fishway, such as vertical slots and orifices, the optimal water velocity should not be higher than 76–79% Uburst at stage 2 and should absolutely not exceed 90–96% Uburst at stage 3.

Water quality safety prediction model for drinking water source areas in Three Gorges Reservoir and its application

In recent years, water pollution accidents have become major ecological environmental pollution ones in China, and bring potential risk to urban drinking water safety. The research aimed to develop a water quality safety prediction model for drinking water source areas in Three Gorges Reservoir and simulate pollutant distribution in water bodies under pollution accident conditions. In this study, a new algorithm of two-dimensional water quantity model was proposed, which incorporated Digital Elevation Model as a computational grid into the Geographic Information System. By comparing the water quality observed values with the predicted values of the study area in 2014, the relative error was less than 6%, the model can be applied in a reasonable range. Furthermore, this study assumed a pollution accident that the Huangjuedu drinking water source area was polluted by TP pollution (level V) of 0.4 mg/L. Based on the statistical annual date of Zhutuo hydrological station in 2016 (as blank group), dispatching test that was conducted by increasing discharge flow of Xiangjia Dam Reservoir. The results shows that the water velocity of intake increased with discharge flow of Xiangjia Dam Reservoir, and that the maximum water velocity was 2.051 m/s. The pollutant concentration of HDWSA intake decreased rapidly with the increase of the discharge flow. When the discharge flow was 0 m3/s, the concentration of intake reached the level III water quality standard after 127.8 min. When the discharge flow was 12,000 m3/s, the concentration of intake reached the level III water quality standard after 116.7 min. In the dispatching test, the rate of migration and diffusion of the pollutant to the lower reaches was greatly affected by the discharge flow of Xiangjia Dam Reservoir. The model could predict the water velocity and pollutant concentrations at the intake, as well as temporal-spatial distributions of pollutants in the whole water source area. Prediction results of the model were helpful for management departments to predict grasp the change of pollutions timely and accurately, and make corresponding plans under accident conditions.

A rapid flood inundation model for hazard mapping based on least squares support vector machine regression

Two‐dimensional shallow water models are widely used tools for flood inundation mapping. However, even if High Performance Computing techniques have greatly decreased the computational time needed to run a 2D inundation model, this approach remains unsuitable for applications that require results in a very short time or a large number of model runs. In this paper we test a non‐parametric regression model based on least squares support vector machines as a computationally efficient surrogate of the 2D shallow water equations for flood inundation mapping. The methodology is initially applied to a synthetic case study consisting of a straight river reach flowing towards the sea. A coastal urban area is then used as a real test case. Discharge in three streams and tide levels are used as predictor variables to estimate the spatial distribution of maximum water depth and velocity in the study area. The suitability of this regression model for the spatial prediction of flood hazard is evaluated. The results show the potential of the proposed regression technique for fast and accurate computation of flood extent and hazard maps.

A Fiscally Based Scale for Tropical Cyclone Storm Surge

AbstractCategorization of storm surge with the Saffir–Simpson hurricane scale has been a useful means of communicating potential impacts for decades. However, storm surge was removed from this scale following Hurricane Katrina (2005), leaving no scale-based method for storm surge risk communication despite its significant impacts on life and property. This study seeks to create a new, theoretical storm surge scale based on fiscal damage for effective risk analysis. Advanced Circulation model simulation output data of maximum water height and velocity were obtained for four storms: Hurricane Katrina, Hurricane Gustav, Hurricane Ike, and Superstorm Sandy. Four countywide fiscal loss methods were then considered. The first three use National Centers for Environmental Information Storm Events Database (SED) property damages and Bureau of Economic Analysis (BEA) population, per capita personal income, or total income. The fourth uses National Flood Insurance Program total insured coverage and paid claims. Initial correlations indicated the statistical mode of storm surge data above the 90th percentile was most skillful; this metric was therefore chosen to represent countywide storm surge. Multiple linear regression assessed the most skillful combination of storm surge variables (height and velocity) and fiscal loss method (SED property damages and BEA population, i.e., loss per capita), and defined the proposed scale, named the Kuykendall scale. Comparison with the four storms’ actual losses shows skillful performance, notably a 20% skill increase over surge height-only approaches. The Kuykendall scale demonstrates promise for skillful future storm surge risk assessment in the analytical, academic, and operational domains.

Study on Water Pressure and Velocity in Cracks of Slab Track

The essence of slab track damage under the coupling effect of train load and water is a coupled hydro-mechanical (HM) fracture, and the core technology is the water pressure calculation. Finite element software ANSYS and CFX are used to analyze the water pressure and speed of slab track cracks under high speed train loads. The results show that, the maximum water pressure appears at the crack tip under loading, and decreases along the crack. The value of water pressure is proportional to load amplitude, square of loading frequency and inversely proportional to crack aperture. On the contrary, the maximum water velocity appears at the crack mouth, and increases along the crack. The value of velocity is proportional to load amplitude, proportional to loading frequency, and inversely proportional to crack aperture. The presented theory can be applied to the stress study of slab track water crack.

Swimming Capabilities of Arctic Grayling

A native population of arctic grayling (Thymallus arcticus) exists in the upper Missouri River drainage of Montana. While formerly abundant, agricultural practices, predation, angling pressure, barriers to mobility, and competition from other species appear to be the causes of decreased presence of artic grayling in the Northwest (Skaar 1989). The purpose of this study was to augment the information base of the swimming ability of arctic grayling and to examine the effect of repeated trials using the same fish. Forty hatchery-raised grayling were separated into two cohorts and reared in an artificial stream. The mean fork length of all fish was 290 mm (SD ± 16). Cohort 1 was tested in a swim chamber experiment once per week for three consecutive weeks. Cohort 2 was tested only once in the swim chamber sixteen weeks later. Each fish was tested by placing it in the chamber initially operating at a low water velocity (30.5 cm s-1) and then regularly increasing the velocity until the fish rested on the screen at the downstream end of the chamber. The maximum water velocity against which each fish held its position was observed, and is reported as the sprint speed (Usprint). Overall the mean Usprint observed was 5.64 BL (body length) s-1 (SD ± 0.78) equal to an absolute velocity of 1.66 m s-1 (SD ± 0.19). Cohort 1 had a mean Usprint of 5.40 BL s-1 (1.62 m s-1) and Cohort 2 had a mean Usprint of 6.33 BL s-1 (1.77 m s-1). There were significant differences, and a generally increasing trend, in Usprint between the successive trials using Cohort 1.

Development and assessment of uni- and multivariable flood loss models for Emilia-Romagna (Italy)

Abstract. Flood loss models are one important source of uncertainty in flood risk assessments. Many countries experience sparseness or absence of comprehensive high-quality flood loss data, which is often rooted in a lack of protocols and reference procedures for compiling loss datasets after flood events. Such data are an important reference for developing and validating flood loss models. We consider the Secchia River flood event of January 2014, when a sudden levee breach caused the inundation of nearly 52 km2 in northern Italy. After this event local authorities collected a comprehensive flood loss dataset of affected private households including building footprints and structures and damages to buildings and contents. The dataset was enriched with further information compiled by us, including economic building values, maximum water depths, velocities and flood durations for each building. By analyzing this dataset we tackle the problem of flood damage estimation in Emilia-Romagna (Italy) by identifying empirical uni- and multivariable loss models for residential buildings and contents. The accuracy of the proposed models is compared with that of several flood damage models reported in the literature, providing additional insights into the transferability of the models among different contexts. Our results show that (1) even simple univariable damage models based on local data are significantly more accurate than literature models derived for different contexts; (2) multivariable models that consider several explanatory variables outperform univariable models, which use only water depth. However, multivariable models can only be effectively developed and applied if sufficient and detailed information is available.

Impact of the Rainfall Duration and Temporal Rainfall Distribution Defined Using the Huff Curves on the Hydraulic Flood Modelling Results

In the case of ungauged catchments, different procedures can be used to derive the design hydrograph and design peak discharge, which are crucial input data for the design of different hydrotechnical engineering structures, or the production of flood hazard maps. One of the possible approaches involves using a hydrological model where one can calculate the design hydrograph through the design of a rainfall event. This study investigates the impact of the design rainfall on the combined one-dimensional/two-dimensional (1D/2D) hydraulic modelling results. The Glinščica Stream catchment located in Slovenia (central Europe) is used as a case study. Ten different design rainfall events were compared for 10 and 100-year return periods, where we used Huff curves for the design rainfall event definition. The results indicate that the selection of the design rainfall event should be regarded as an important step, since the hydraulic modelling results for different scenarios differ significantly. In the presented experimental case study, the maximum flooded area extent was twice as large as the minimum one, and the maximum water velocity over flooded areas was more than 10 times larger than the minimum one. This can lead to the production of very different flood hazard maps, and consequently planning very different flood protection schemes.

Experimental and numerical investigations of heat transfer and thermal efficiency of an infrared gas stove

An infrared gas stove is a low-pressure gas stove type and it has higher thermal efficiency than the other domestic cooking stoves. This study considers the computationally determine water and air temperature distributions, water and air velocity distributions and thermal efficiency of the infrared gas stove. The goal of this work is to investigate the effect of various pot diameters i.e. 220 mm, 240 mm and 260 mm on the water and air temperature distributions, water and air velocity distributions and thermal efficiency of the infrared gas stove. The time-dependent heat transfer equation involving diffusion and convection coupled with the time-dependent fluid dynamic equation is implemented and is solved by using the finite element method (FEM). The computer simulation study is validated with an experimental study, which is use standard experiment by LPG test for low-pressure gas stove in households (TIS No. 2312-2549). The findings revealed that the water and air temperature distributions increase with greater heating time, which varies with the three different pot diameters (220 mm, 240 mm and 260 mm). Similarly, the greater heating time, the water and air velocity distributions increase that vary by pot diameters (220, 240 and 260 mm). The maximum water temperature in the case of pot diameter of 220 mm is higher than the maximum water velocity in the case of pot diameters of 240 mm and 260 mm, respectively. However, the maximum air temperature in the case of pot diameter of 260 mm is higher than the maximum water velocity in the case of pot diameters of 240 mm and 220 mm, respectively. The obtained results may provide a basis for improving the energy efficiency of infrared gas stoves and other equipment, including helping to reduce energy consumption.