Hydraulic Jump Research Articles

Effect of Lateral Jets on the Characteristics of Spatial Hydraulic Jump

Effect of Lateral Jets on the Characteristics of Spatial Hydraulic Jump

The Dynamic Mechanism and Optimal Parameters of Hydraulic Jump Induced Disk Floatation

The Dynamic Mechanism and Optimal Parameters of Hydraulic Jump Induced Disk Floatation

Investigation of the Perfect Hydraulic Jump in Horizontal Rectangular Channel

Accelerating the process of transition from supercritical to subcritical flow, by formation a forced hydraulic jump at the contract section (Forced perfect hydraulic jump), is one of the most important measures, in decreasing flow velocity, water energy dissipation and alleviation the scouring problem, leading to lessening the required protection length against the erosion issues in the bed of downstream of the channel. In the current study, physical model was prepared precisely at fluid mechanics laboratory in the faculty of Engineering/Alkhums at Elmergib University. Comprehensive experiments were conducted to evaluate measured and calculated characteristics of the perfect free jump, and consequently, the existence of the perfect hydraulic jump is investigated. Eventually, equation was derived that might be used to guarantee the existence of a free perfect jump, which is the limiting condition between both repelled and drowned jumps as well as, the limiting condition between both repelled and drowned jumps was graphically found.

KAJIAN LONCATAN HIDROLIK PADA KOLAM OLAK MODEL FISIK BENDUNGAN KRUENG SABEE KABUPATEN ACEH JAYA

Hydraulic jump is a phenomenon that occurs in stilling basins from supercritical to subcritical conditions. The design of the Krueng Sabee dam aims to meet the needs of the people in the Aceh Jaya district. So this study aims to identify the behavior of hydraulic jumps that occur in energy dissipators in the form of jump height and energy dissipation to obtain an optimal design. The research method is a physical model study with an undistorted scale of 1:30. The energy dissipator used in this plan is the USBR IV stilling basin type. The discharge flowed on the physical model of the Krueng Sabee dam with return periods of Q2, Q5, Q10, Q25, Q50, Q100, and Q1000 years. Tests were carried out on 2 types of models, namely the Detail Engineering Design (DED) model series and the modified model series. In the modified model series, the addition of a 3 m high slope with a slope of 1:2, the elevation of the stilling pool was lowered to a depth of 3 m, and the addition of the length of the stilling pool was 4.8 m. The results of this study indicate that the modified series model is more optimal than the DED series model. The pattern of high jump and jump length increased against Froude numbers on the upstream jump showed a series of modified models better. The results of energy dissipation observations show that the modified model series is more competitive. The highest relative hydraulic jump ((y1-y2)/y1) that occurred in the modified model series was 19.40 (almost 3 times higher) than the highest ((y1-y2)/y1) model of the DED series model, which was 6.54. In the modified series, the farther Lj/y1 occurs the greater ∆E/y1 generated. On the other hand, there is a large decrease in relative energy dissipation (∆E/y1) with increasing relative hydraulic jump length (Lj/y1) in the DED series. The results of the analysis show a large decrease in ∆E/y1 to an increase in the ratio y1/y2 in both series of stilling basin models.

Prediction of Hydraulic Jumps on a Triangular Bed Roughness Using Numerical Modeling and Soft Computing Methods

This study investigates the characteristics of free and submerged hydraulic jumps on the triangular bed roughness in various T/I ratios (i.e., height and distance of roughness) using CFD modeling techniques. The accuracy of numerical modeling outcomes was checked and compared using artificial intelligence methods, namely Support Vector Machines (SVM), Gene Expression Programming (GEP), and Random Forest (RF). The results of the FLOW-3D® model and experimental data showed that the overall mean value of relative error is 4.1%, which confirms the numerical model’s ability to predict the characteristics of the free and submerged jumps. The SVM model with a minimum of Root Mean Square Error (RMSE) and a maximum of correlation coefficient (R2), compared with GEP and RF models in the training and testing phases for predicting the sequent depth ratio (y2/y1), submerged depth ratio (y3/y1), tailwater depth ratio (y4/y1), length ratio of jumps (Lj/y2*) and energy dissipation (ΔE/E1), was recognized as the best model. Moreover, the best result for predicting the length ratio of free jumps (Ljf/y2*) in the optimal gamma is γ = 10 and the length ratio of submerged jumps (Ljs/y2*) is γ = 0.60. Based on sensitivity analysis, the Froude number has the greatest effect on predicting the (y3/y1) compared with submergence factors (SF) and T/I. By omitting this parameter, the prediction accuracy is significantly reduced. Finally, the relationships with good correlation coefficients for the mentioned parameters in free and submerged jumps were presented based on numerical results.

Comparison of oxygen transfer efficiency using new types of baffle blocks

Oxygen is needed in water to maintain the natural ecological balance and the health of organisms. The amount of dissolved oxygen (DO) in water can be increased naturally in different ways. In particular, some hydraulic structures are designed so reoxygenation of water occurs spontaneously over a short distance and in a short time. Baffled chutes are designed to dissipate the energy of flow in irrigation systems, wastewater systems and stormwater systems. Staggered baffle blocks placed in a chute channel not only dissipate the energy of the water but also allow free oxygen transition between the water–air surface by means of hydraulic jumps. While water flows over, between and around the blocks, air bubbles are entrained into the water. The entrained air bubbles in the flow start to dissolve within the chute and the DO concentration in the water thus increases. In this study, the amount of DO was determined for baffle blocks with six different geometric shapes, different flow discharges and angle variations (10° ≤ α ≤ 56°). The oxygen transfer efficiency of the new baffle blocks designed in this study was found to be very effective. Different block types were found to have greater oxygen transfer efficiency for chutes with different slopes.

Oblique undular hydraulic jumps in turbulent free‐surface flows

AbstractSteady turbulent near‐critical free‐surface flow over a slightly inclined bottom with an oblique roughness discontinuity is considered. An asymptotic analysis for Froude numbers close to the critical value 1 and large Reynolds numbers results in an extended Korteweg–de Vries (KdV) equation describing the free‐surface elevation without the need of turbulence modeling. Two new integral relations can be derived from the extended KdV equation. For enlarged downstream bottom roughness, a new type of undular jump solutions with fully developed flow both upstream and downstream exists. Numerical solutions of the extended KdV equation show that an increasing downstream bottom roughness enhances the development of undulations.

An efficient three-dimensional non-hydrostatic model for undular bores in open channels

A three-dimensional (3D) non-hydrostatic model is presented to simulate open-channel free-surface flows involving undular bores. The 3D unsteady mass conservation and momentum equations are solved using an explicit projection method in a nonstandard staggered grid. The grid system is built from a two-dimensional horizontal structured grid by adding horizontal layers. The model is validated using four typical benchmark problems, including undular bore development, an undular bore generated by a sudden discharge, and two test cases involving undular hydraulic jumps. The proposed model results are compared with experimental data and results from other models. Overall, the agreement between the proposed model results and experimental data is generally good, demonstrating the capability of the model to resolve undular bores. In addition, the non-hydrostatic pressure field under the undular free surface is revealed, and the efficiency of the proposed model is presented. It is shown that the proposed model behaves better than a volume of fluid model in terms of efficiency, because the proposed model can use fewer computational grid cells to resolve undular bores in open channels.

Effects of Divergence Shape on the Characteristics of Hydraulic Jump in Stilling Basins Using Numerical Simulation and Neural Networks

Measures such as sudden cross-sectional divergence is among the factors affecting the characteristics of hydraulic jump. If for any reason it is not possible or cost-effective to provide the depth required for the hydraulic jump, then gradual or sudden flow cross-sectional divergence can be a good way to reduce the depth required for the jump. In this research, using the neural network and FLOW-3D numerical model, a three-dimensional (3D) model for fluid simulation, the effect of sudden divergence stilling basin on characteristics was simulated. The results of the neural network are very close to the physical model. The study revealed that 3D simulation using Flow-3D software could simulate a hydraulic jump with an average error of 2.41%. The efficiency of stilling basins divergent was calculated to be 71%, which is higher than the classic stilling basins with an efficiency of 53.3%. Depth after jumping in divergent stilling basins modeled at 27.8 and 41.4 l/s was found to be 12 and 25% less than classic basins, respectively. Compared to the classical mode in the divergent stilling basins parabolic, gradual, and sudden, the decrease in jump length was found to be 25.9%, 27.5%, and 31.8%, respectively. The results showed that the sudden divergent stilling basin has the best performance in terms of hydraulic parameters.

Turbulent thermohaline hydraulic jumps

Turbulent entrainment properties of thermohaline internal hydraulic jumps in quiescent ambient water are investigated. Underflow and overflow jumps are considered. The study is mainly concerned with thermohaline buoyancy effects on flow development. The thermohaline buoyancy is determined from a seawater equation of state, which is nonlinear in temperature and linear in salinity, and is accurate throughout the range of temperature and salinity of interest (T = 0 to 40 °C and S = 0 to 40 ppt). The results indicate that thermohaline buoyancy produces smaller less diluted underflow jumps and larger more diluted overflow jumps. These nonlinear buoyancy effects are particularly significant when buoyancy arising from temperature and salinity act in opposite directions. Hydraulic controls by vertical and/or horizontal constrictions downstream reveal, using a matching technique, unique stationary miscible jump solutions.

Numerical validation of novel scaling laws for air entrainment in water

The Froude scaling laws have been used to model a wide range of water flows at reduced size for almost a century. In such Froude scale models, significant scale effects for air–water flows (e.g. hydraulic jumps or wave breaking) are typically observed. This study introduces novel scaling laws, excluding scale effects in the modelling of air–water flows. This is achieved by deriving the conditions under which the governing equations are self-similar. The one-parameter Lie group of point-scaling transformations is applied to the Reynolds-averaged Navier–Stokes equations, including surface tension effects. The scaling relationships between variables are derived for the flow variables, fluid properties and initial and boundary conditions. Numerical simulations are conducted to validate the novel scaling laws for (i) a dam break flow interacting with an obstacle and (ii) a vertical plunging water jet. Results for flow variables, void fraction and turbulent kinetic energy are shown to be self-similar at different scales, i.e. they collapse in dimensionless form. Moreover, these results are compared with those obtained using the traditional Froude scaling laws, showing significant scale effects. The novel scaling laws are a more universal and flexible alternative with a genuine potential to improve laboratory modelling of air–water flows.

Undular Hydraulic Jumps: Critical Analysis of 2D RANS-VOF Simulations

AbstractNumerical simulation of undular hydraulic jumps, which occur at an inflow Froude number slightly above unity, remain an important and enigmatic challenge in hydraulic engineering. In this s...

Asymmetric Structures of a Squall-Line MCS over Taiwan with Significant Hydraulic Jumps

On 19 April 2019, a mature squall-line mesoscale convective system (MCS) with the characteristics of a leading convective line and trailing stratiform landed on Taiwan, resulting in strong gust wind and heavy rainfall. This squall-line MCS became asymmetric after landfall on Taiwan. Two sets of idealized numerical simulations (mountain heights and low-level vertical wind shear) using the Weather Research and Forecasting (WRF) model were conducted to examine the impacts of realistic Taiwan topography on a squall-line MCS. Results showed numerous similarities between the idealized simulations and real-case observations. The low-level Froude number which considered the terrain height (Fmt) was calculated to examine the blocking effect of the Taiwan terrain, and the cold pool (determined by − 1.5 K isotherm) was found to be completely blocked by the 500-m height contour. The northeast-southwest orientation of the Snow Mountain Range (SMR), and the north–south orientation of the Central Mountain Range (CMR) led to the upwind side asymmetry. On the other hand, the lee-side asymmetry was associated with different intensities and occurrence locations of the hydraulic jump between the SMR and southern CMR, and the cold-pool Froude number (Fcp) indicated the flow-regime transition from subcritical to supercritical.

Computational Analysis of Fluid Flow through a Sine-Curved Channel with High Reynolds Number

In this paper, we attend to investigate the steady flow of a Newtonian fluid through a sine-curved channel working with the least-square technique of Galerkin’s approach. We implement the whole simulation using Comsol Multiphysics 5.4. To study the fluid flow through this channel, we take the Reynolds numbers in the range from 1000 to 10,000 and amplitude of the sine-curved channel in the range from 10 cm to 30 cm. We examine the flow rate and pressure at the outlet. It is observed that, at the outlet, maximum speed is increasing linearly along the Reynolds number and that the maximum pressure settled a negative relationship with the Reynolds number when increased. It is also determined that due to an increase in the hydraulic jumps, when increasing the amplitude of vibration of the channel, the velocity of flow got fluctuated at the above walls, which also results in a decline in the pressure from the inlet to exit of the channel. Moreover, the several correlations keeping amplitude as constant have been developed for the maximum flow velocity magnitude at the exit of the channel relating to the Reynolds number. These correlations will be definitely used for the future production and comparison for the fluid flow for the curvy channel.

Genesis and evolution of large-scale sediment waves in submarine canyons since the Penultimate Glacial Maximum (ca. 140 ka), northern South China Sea margin

Sediment waves are common on the seafloor, but large-scale ones developed in submarine canyons are rarely reported. In this study, we document for the first time the Quaternary deep-water canyon-confined large-scale sediment waves developed on the northern South China Sea margin based on the analysis of a high-quality 3-D seismic reflection volume combined with a 2-D multichannel seismic reflection profile and three wells. Results show that the onset of these canyon-confined large-scale sediment waves can be dated back to the Penultimate Glacial Maximum (PGM)(ca.140 ka). This was the last period for the Pearl River Delta to prograde over the shelf edge. And these sediment waves have continued to develop and migrate upslope until present. The large-scale sediment waves pertaining to the PGM have a dominant down-slope asymmetrical 2-D morphology with wavelengths of 1.059–6.090 km and wave heights of 3.3–32.5 m. The present large-scale sediment waves show an up-slope asymmetrical 2-D morphology with dimensions of 0.667–5.628 km wavelength and 2.7–14.0 m wave height, which are smaller relative to those at the PGM. Grain sizes of the sediment waves at the PGM and present are interpreted to be coarse, inferred from seismic reflection data by high amplitude reflections (HARs). After a comprehensive analysis of the types of sediment-laden flows, the sediment provenances, the seafloor topography and the features of the sediment waves, these large-scale sediment waves might be interpreted as cyclic steps generated by the down-slope flowing supercritical turbidity currents and associated internal hydraulic jumps along high gradient (approximately greater than 1.28°) canyon thalwegs characterized by numerous slope breaks. The evolution of the large-scale sediment waves from partially depositional at the PGM to erosion-dominated at the present is controlled by variations of the sediment supply and the submarine slope accommodation along the canyon thalweg, which is manifested in the co-evolution of the sediment waves with the canyon. The findings of this study tell us that in addition to axial channels and mass-transport complexes, large-scale sediment waves can also develop on the canyon floor, which helps to improve our understanding of the complex canyon processes. The ‘large-scale sediment waves’ described here may be a new potential deepwater-reservoir element for the deep-water hydrocarbon exploration associated with submarine canyons.

Rates of bubble diffusion and turbulence dissipation in highly aerated hydraulic jumps

Air–water mixing associated with high turbulence is a common hydraulic phenomenon, where the transport of entrained air bubbles and the dissipation of turbulent energy are key processes affecting the air–water mass transfer. Herein hydraulic jumps were selected as a seminal case of self-air-entrainment in transitional water flow, and the air–water flow properties were investigated at high Froude numbers from 10.5 to 13.5. The analysis of air concentration distributions and bubble size spectra enabled deviation of the rates of bubble diffusion and turbulence dissipation. The study was facilitated with re-analyses of earlier experimental data for smaller Froude numbers between 3.8 and 10. The spatial evolution of the diffusion and dissipation rates suggested that the diffusion of air bubbles and dissipation of turbulent structures were not independent processes, and, at high Froude numbers, the mix of air and water was subject to re-aeration of the turbulent shear layer by the roller.

‘Isolated base‐of‐slope aprons’: An oxymoron for shallow‐marine fan‐shaped, temperate‐water, carbonate bodies along the south‐east Salento escarpment (Pleistocene, Apulia, southern Italy)

AbstractThis paper regards the lower Pleistocene temperate‐water carbonate deposits disconformably overlying an escarpment made up of faulted Cretaceous to Miocene limestones of the Apulia Foreland (southern Italy). Study deposits discontinuously crop out along the present‐day eastern Salento sea cliff, and form isolated fan‐shaped bodies, up to 1 km wide and up to 40 to 50 m thick, each of them covering an area of a few square kilometres. The internal arrangement of beds is represented by up to 25° to 30° lobate, seaward dipping clinobeds thinning and onlapping onto a rocky foreslope in the proximal sector and passing to gently inclined to sub‐horizontal strata in the distal sector. Seven facies were distinguished, mainly composed of coarse‐grained skeletal carbonates made up of a heterozoan association including coralline algae, large and small benthic foraminifera, echinoids, molluscs, bryozoans and serpulids. Since clinobeds were formed thanks to hyperconcentrated density flows (grain flows) bypassing the upper part of the inherited escarpment, these skeletal grains represent ex situ deposits whose shallow‐marine factory was located upward (landward) with respect to the bypassed zone, likely in the almost flat area on top of the Salento Peninsula. Clinobeds are often affected by tens of metres wide and long channel‐like structures interpreted as landslide scars. Inside these gullies, contorted beds (slumps) or matrix‐supported intra‐bioclastic floatstone/rudstone (massive deposits) are present. The occurrence of supercritical‐flow structures (for example, backset‐bedded beds) indicates the development of hydraulic jumps along the steep slope of gullies. Since these clinostratified, fan‐shaped carbonate bodies represent carbonate slopes, and that the latter are known as aprons, normally related to linear sourced sediments, an acceptable oxymoron for studied fan‐shaped carbonate bodies is suggested: ‘isolated base‐of‐slope aprons’.

PIV and BIV Measurements of Roller in Hydraulic Jumps

Park, M.; Kim, H.S.; Choi, S., and Ryu, Y.-U., 2021. PIV and BIV measurements of roller in hydraulic jumps. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 56–60. Coconut Creek (Florida), ISSN 0749-0208. This study performed an experimental investigation on roller in hydraulic jump. Based on the similarity between tidal bore and hydraulic jump, the turbulence flow and free surface fluctuation of the hydraulic jump roller were analyzed with adjustment of downstream water level. To obtain instantaneous flow field including bubbly flow, PIV and BIV technique with shadowgraphy was applied. The result found that the streamwise turbulent flow was dominated at the lower part of roller while the vertical turbulence increased near the water surface of roller in hydraulic jump. The water level showed a large fluctuation as a hydraulic jump occurred. These challenges identified the detailed view of velocity and free surface of roller region can be provided using image analysis.

Experimental Investigation of the Joint Effect of Flow Expansion and Submerged Vanes on Hydraulic Jump Characteristics

Experimental Investigation of the Joint Effect of Flow Expansion and Submerged Vanes on Hydraulic Jump Characteristics

Facies and bed type characteristics of channel‐lobe transition deposits from the Oligocene‐Miocene Tajau Sandstone Member, Kudat Formation, Sabah, Malaysia

Channel‐lobe transition zones (CLTZs) are identified in many modern deep‐water systems, but few exhumed examples have been identified. Exposures of the Oligocene‐Miocene Tajau Sandstone Member (TSM), Kudat Formation, northern Sabah, Malaysia, provides the opportunity to document a CLTZ from an active basin margin. This work provides the first detailed field‐based sedimentological logging to produce a quantitative database on facies, sedimentary structures, bed type, and statistical analysis. This is particularly important to produce a robust stratigraphic framework of the TSM. Sedimentary facies support interpretation of subaqueous sediment density flows, and key features, including scour‐fills, antidunes, and dune‐scale bedforms, suggest changes in gradient and/or flow confinement and the development of hydraulic jumps. Eight bed types are recognized including: (a) tripartite beds with a debrite (BT1), interpreted as hybrid event beds recording downslope flow transformation between turbulent and laminar states; (b) beds with a mixture of depositional, erosional, and bypass features (BT2, BT4, BT5), interpreted as recording the transitions between supercritical and subcritical flow conditions triggered by hydraulic jumps; (c) bipartite beds with a basal massive sandstone overlain by fine‐grained facies (BT3), interpreted as hyperconcentrated flow deposits with evidence of downcurrent flow transformation; (d) bipartite beds with a basal high‐density turbidite sharply overlain by a low‐density turbidite (BT6), interpreted as turbidites with evidence of sediment bypass; (e) basal tractive structures capped by fine‐grained facies as the product of reworking of very coarse‐ to coarse‐grained sediments caused by lateral spreading of turbulent flows; and (f) Bouma Tbcde sequences (BT8) interpreted as high‐to‐low‐density turbidites. Our depositional model for the TSM comprises: (a) an aggradational channel‐lobe transition zone (CLTZs/BTA 1 and BTA 2) which was dominated by hydraulic jumps and sediment bypass; and (b) stacked lobe (i.e., lobe‐axis/BTA 3a, lobe‐off axis/BTA 3b, frontal lobe fringe/BTA 3c, and distal lobe fringe/BTA 3d) located in the northern and southern parts of the study area, which is dominated by tabular, sheet‐like elements bioturbated with the Nereites ichnofacies. The aggradational stacking of CLTZs deposits observed in the TSM may be explained by high subsidence rates combined with high sediment supply rates associated with a tectonically active margin setting.