Dam-break Flow Research Articles

Dam break flow through rigid-emergent vegetation

Dam failures pose a significant threat to life and property. This study investigates the potential of rigid emergent vegetation to attenuate dam break waves, reducing their destructive impact. Experiments explored the effect of varying vegetation field lengths on wave propagation. Wooden cylinders with consistent diameter (1.0 cm) and density (0.067) simulated the rigid vegetation in a straight, flat rectangular channel. Four different vegetation lengths and three bore conditions for different reservoir and tailwater depths were examined to analyze their influence on dam break wave behavior. The results demonstrate the effectiveness of vegetation in dissipating wave energy, leading to a rapid decrease in wave height and celerity. Interestingly, increasing vegetation length significantly attenuates the wave height downstream of the vegetation zone, while having no significant impact on the reflection wave height upstream of the vegetation. This finding highlights the targeted effectiveness of strategically placed vegetation in shielding downstream areas. The study also clarifies that celerity can be calculated using shallow water equations for both upstream and downstream regions with wave height and tailwater depth. However, within the vegetation, drag forces significantly reduce celerity. A novel equation, derived from wavefront profiles, was proposed and validated to accurately calculate celerity within the vegetation field. These findings provide valuable data for validating numerical models simulating dam break wave interactions with vegetation.Graphical abstract

Observation of Two-Dimensional Dam Break Flow and a Gaseous Phase of Solitons in a Photon Fluid.

We report the observation of a two-dimensional (2D) dam break flow of a photon fluid in a nonlinear optical crystal. By precisely shaping the amplitude and phase of the input wave, we investigate the transition from one-dimensional (1D) to 2D nonlinear dynamics. We observe wave breaking in both transverse spatial dimensions with characteristic timescales determined by the aspect ratio of the input box-shaped field. The interaction of dispersive shock waves propagating in orthogonal directions gives rise to a 2D ensemble of solitons. Depending on the box size, we report the evidence of a dynamic phase characterized by a constant number of solitons, resembling a 1D soliton gas in integrable systems. We measure the statistical features of this gaslike phase. Our findings pave the way to the investigation of collective solitonic phenomena in two dimensions, demonstrating that the loss of integrability does not disrupt the dominant phenomenology.

The Assessment of Peak Discharge Increment Due to Land Use Change in the Serang Welahan Drainage 1 (SWD 1) River, Central Java Province, Semarang

SWD1 River is located in one of those flood-prone areas in Central Java that generates flood hazards causing high risk to the surrounding rice fields and communities. However, a comprehensive study of flood hazards in SWD1 River has never been conducted. Nowadays, previous comprehensive flood studies in Indonesia only available for several very developed areas, such as the Jakarta Flood [1] – [5], Bandung Flood and Solo Flood , or new iconic area for mangrove conservation such as Langsa City . Most previous studies conclude that flood hazards in Indonesia are commonly generated by rain runoff, tides, and dam break flows, or a combination of these generators . Existing conditions show that SWD 1 is unable to accommodate runoff from the Wulan River, causing flooding. Based on rainfall data from BMKG, the maximum rainfall per month for a year reaches 323 mm. This study is an effort to analyze the impact of land use change.The research method used analysis of the influence of changes in CN (Curve Number) due to changes in land use on flood discharge as shown through changes in the Soil Conservation Service (SCS-CN) hydrograph on discharge and runoff volume. The selection of the SCS-CN method is due to its widespread adoption in various regions, its extensive use in numerous analytical studies, and its suitability for the characteristics of the watershed under review.The analysis results show that there has been a change in flood discharge from 2019 and 2022 with values of 366.920 and 371.154 m3/second. The discharge values did not change significantly because the CN values were as follows, 83.25 and 83.36. Through analysis, it can be seen that an increase in discharge of 1.14% from 2011 to 2022.The several alternatives are needed to reduce flooding, such as watershed conservation upstream, minimizing land use changes and building flood mitigation infrastructure downstream.

A Smoothed Particle Hydrodynamics Approach for One-Dimensional Dam Break Flow Simulation with Boussinesq Equations

A Smoothed Particle Hydrodynamics Approach for One-Dimensional Dam Break Flow Simulation with Boussinesq Equations

Resolving subgrid-scale structures for multiphase flows using a filament moment-of-fluid method

Multiphase flows are present in many industrial and engineering applications as well as in some physical phenomena. Capturing the interface between the phases for complex flows is challenging and requires an accurate method, especially to resolve fine-scale structures. The moment-of-fluid (MOF) method improves drastically the accuracy of interface reconstruction compared to previous geometrical methods. Instead of refining the mesh to capture increased levels of detail, the MOF method, which uses zeroth and first moments as well as a conglomeration algorithm, enables subgrid structures such as filaments to be captured at a small extra cost. Coupled to a finite volume Navier–Stokes solver, the MOF method has been tested on a fixed grid and validated using well-known benchmark problems such as the dam break flows, the Rayleigh–Taylor and Kelvin–Helmholtz instability problems, and a rising bubble. The ability of the novel filament MOF method to capture the filamentary structures that eventually form for the Rayleigh–Taylor instability and rising bubble problems is assessed. Good agreement has been found with other numerical results and experimental measurements available in the literature.

Development of a smoothed particle hydrodynamics model for porous media flows with enhanced volume conservation and the revisit of the mass conservation equation

Porous media exist extensively in hydraulic and coastal engineering structures, while the modeling of wave/flow interaction with porous media remains challenging. This work develops a smoothed particle hydrodynamics (SPH) model for accurately simulating wave/flow interaction with porous media. The mass and momentum conservation equations incorporating the mixture theory are adopted. The resistant forces of the solid skeleton of porous media on fluid flows are described by the nonlinear empirical formula. The research contributions of the work lie in two aspects. First, two categories of mass conservation equations for porous media flow are revisited and analyzed to examine the influences of the local time derivative term of fluid volume fraction on simulation results. Second, the Volume Conservation Shifting scheme is, for the first time, introduced into SPH to enhance volume conservation for simulating porous media flows. The developed SPH model is validated by an analytical case of seepage flows in a U-tube with porous media and then applied to study four benchmark examples involving both saturated and unsaturated porous media, i.e., dam-break flow through a crushed stone dam, rapid seepage flow through a rockfill dam, solitary wave propagation over a porous seabed, and solitary wave propagation over a submerged porous breakwater. The morphological features and dynamic pressure heads of the porous media flows have been satisfactorily predicted, demonstrating the good accuracy and enhanced volume conservation of the developed SPH model.

Gaussian smoothed particle hydrodynamics: A high-order meshfree particle method

Smoothed particle hydrodynamics (SPH) has attracted significant attention in recent decades, and exhibits special advantages in modeling complex flows with multiphysics processes and complex phenomena. Its accuracy depends heavily on the distribution of particles, and will generally be lower if the particles are distributed non-uniformly. A high-order SPH scheme is proposed in the present work for simulating both compressible and incompressible flows. It uses a Gaussian quadrature rule to perform the particle approximation of SPH by introducing Gaussian nodes. Unfortunately, the Gaussian nodes hardly overlap with SPH particles due to the Lagrangian feature, and thus we use a high-order interpolation method to obtain the corresponding physical quantities at the Gaussian nodes. The accuracy and robustness of the proposed Gaussian SPH are demonstrated by several numerical tests, including the Sod problem, Poiseuille flow, Couette flow, cavity flow, Taylor–Green vortex and dam break flow, and a convergence analysis is also conducted to evaluate the effects of particle resolution and distribution for reconstructing a given function. The simulation results for each test case are in good agreements with the available analytical, experimental or numerical results, showing that the proposed Gaussian SPH method is accurate and reliable but expensive for simulating compressible and incompressible flow problems.

SPH simulations of complex 3D fluid–solid interactions with an improved single-layer particle boundary technique preventing boundary penetration

The smoothed particle hydrodynamics (SPH) method has been widely used to simulate fluid–solid interaction (FSI) problems. The solid boundary treatment under complex geometric configurations has always been a hot topic in the SPH numerical simulation. An improved single-layer particle technique combined with an effective anti-penetration boundary improvement algorithm is proposed in this paper, which allows for multi-resolution single-layer particle distribution and effectively prevents particle penetration under complex geometric configurations. Four engineering problems are simulated with the improved technique: dam-break flows with a rectangular prism, water entry of a revolution body, oscillations of a floating body, and gearbox operation. The simulation results of four engineering problems are in good agreement with the reference results, which demonstrates that the improved single-layer particle boundary technique proposed in this paper can accurately simulate the FSI problem of complex geometric configurations.

Numerical investigation on the evolutionary characteristics of landslide dam-break flow in a wet-bed channel with riparian vegetation

Riparian vegetation always grows on both sides of a natural river during a dam-break event, while the river typically retains some water instead of completely drying out. The RNG k-ϵ turbulence model is employed to examine the evolutionary characteristics of the dam-break flow in the downstream vegetated channel. This model facilitates the analysis of water-level fluctuations, velocity distributions, and the retardation effects of vegetation on the dam-break flow by varying the initial water depth (IWD) in the downstream channel. Results indicates that as the water depth in the downstream channel increases, the dam-break wave tends to form more readily, possesses a larger amplitude, and the duration of rapid congestion in the dam-break current decreases. Hence, the surface velocity gradually declines and shows an intermittent distribution. Vegetation impedes the flow evolution in the vegetated area, an effect that diminishes progressively with increasing IWD. In contrast, vegetation hastens the evolution of water flow in the main channel, which remains minimally affected by the IWD.

Experimental study on the influence of water depth and bed slope variations on dam-break flood wave propagation

Damage to dam structures frequently results in catastrophic consequences. Consequently, understanding of the characteristics of the movement of dam-break flow along the sloping wet bed can assist in the issuance of timely flood warnings and risk mitigation. In this study, a series of large-scale flume experiments was conducted with the objective of investigating the effects of upstream and downstream water depth and bed slope on the propagation of dam-break waves. The water level is measured and processed to calculate the wavefront velocity. Results show that the wave propagation behavior can be classified as bore and undular waves through the global Froude numbers (Frx) and local Froude numbers (Frl). When Frx < 1.225 or Frl < 1.475, the dam-break wave propagates as the undular wave. In the undular wave state, the wavefront velocity (U) decreases with increasing water depth ratio α. Additionally, the U with Frx shows a similar trend, where the experimental value surpasses the analytical solution. The dimensionless maximum wave height (ΔHmax) increases with Frx and then decreases. The deviation from the analytical solution ranges between 67.22% and 127.38%. When Frx > 1.225 or Frl > 1.475, the dam-break wave propagates as the bore wave. In the bore wave state, the U increases slightly with the water depth ratio α, while the change rule of U with Frx is similar to it. The dimensionless maximum wave height (ΔHmax) remains relatively constant as Frx increases, showing a high degree of consistency with the analytical solution. The presence of bed slope results in increased wavefront velocity and wave heights, while an increase in α results in the emergence of more pronounced undular wave phenomena. Furthermore, the experimental results are compared with existing analytical solutions, and the validity of the analytical solutions and their limitations are discussed.

Hydrodynamic simulation of oil-water dam-break flows through porous media

In the present work, the problems of oil-water dam-break flow interaction with porous structures are numerically investigated using the coupled Volume-Of-Fluid model (VOF) and non-linear Darcy-Brinkman-Forchheimer model. The accuracy of the developed model is verified through rigorous validation against various demanding benchmark scenarios. These included mixed convection heat transfer in a square porous cavity, the ascent of a single bubble in both fully and partially filled containers, and the interaction of waves with porous structures. Comparative evaluation against existing literature confirmed the reliability and effectiveness of the numerical approach in accurately simulating intricate fluid dynamics within porous media.Subsequently, the validated numerical model is utilized to examine the hydrodynamic behaviour of oil-water dam-break flows through porous media. In the first scenario, a rectangular oil column is positioned atop a rectangular water column. In the second scenario, the two columns are arranged sequentially beside each other. The effects of these arrangements on the resultant pressure shock and hydrodynamic behavior have been investigated. The findings results vividly reveal that the morphology and hydrodynamic characteristics of the dam-break flow are significantly influenced by the presence of the porous matrix. Furthermore, the results showed that the resultant shock pressure is considerably affected by the initial positions of oil and water. The obtained results are depicted in forms of contours of pressure and volume fraction fields and are discussed in details.

Model of bores interaction in the swash

This paper examines the impact of wave interactions in the inner-surf zone, including the swash, on shoreline excursion dynamics. Specifically, the study focuses on how the time lag between consecutive waves and the slope of the beachface affect shoreline dynamics. To investigate this, a laboratory experimental setup is developed to study the behaviour of two consecutive bore-type waves travelling over a fluid layer with constant depth, representing an idealized inner-surf zone, before impacting an inclined solid plane with slope β, representing the beachface. Bore waves are generated using two dam-break flow devices, with a controlled time lag Δt between them. This simplified physical model allows for the assessment of semi-theoretical predictive models based on shallow water approximation, resulting in ballistic-type models for shoreline motion. By combining these approaches, the study characterizes different flow regimes in the (Δt,β) parameter space. It is observed that varying Δt at a fixed β distinguishes four interaction regimes, either wave–wave interaction in the inner-surf zone or wave-swash interaction in the swash, with possibilities of merging or collision depending on wave orientation. In particular, increasing Δt leads to either bore–bore merging in the inner-surf, bore-runup merging in the swash, bore-backwash collision in the swash or bore–bore collision in the inner-surf. Bore–bore merging and bore-runup merging enhance runup, peaking when Δt is such that merging occurs near the transition from the inner-surf to the swash. On the contrary, bore-backwash collision results in additional dissipation of the second bore’s dynamics, leading to a reduced shoreline extension compared to that induced by the first bore. All processes within the swash, including the transition between bore-runup and bore-backwash regimes, as well as the enhancement and extra dissipation of the second bore’s swash excursion, exhibit some level of dependence on β. Overall, the results from this physical model help characterize and explain local mechanisms triggered by wave interaction near the shoreline. Validating this model’s relevance warrants specific attention through comparisons with field data. As an initial validation attempt, field data extracted from the literature are compared to the physical model, showing promising agreement.

New optical hydrodynamic representation of dispersive two-phase

In this paper, we construct the photonic dam-break flow problem for [Formula: see text] magnetic fluid in a spherical model. Then, we obtain an optical magnetic transform for the NLSE in hydrodynamical form. By dispersive photonic hydrodynamic representation, normal of surface [Formula: see text] flow is obtained. Thus, we design two-phase [Formula: see text] flow dispersion density in a spherical model. Finally, we have new modeling of dispersive dam break two-phase [Formula: see text] flux.

Macroscopic modeling of urban flood inundation through areal-averaged Shallow-Water-Equations

An areal-averaged form of classical Shallow-Water-Equations is developed in conjunction with Finite-Volume-Method for capturing sub-grid bed variation. The averaging mechanism treats sub-grid obstacles through depth-dependent-area-averaged porosity at the macroscopic level. This porosity assumes a binary distribution (0,1) for a resolution fine enough to treat bed-variation separately, resulting in convergence of the developed framework to classical form. An attempt has been made to incorporate the unresolved fine-scale flow-information (e.g., micro-scale and cross-scale interaction components) in terms of the macroscopic variables through a non-linear closure model. An augmented approximated Riemann solver incorporates varying source–sink terms within interfacial fluxes along with discontinuous porosity and bed variation. The model is applied to three test-cases ranging from wave-interaction with trapezoidal porous block to dam-break flows through obstacle(s) with varying grid configurations. The coarse-scale formulation, along with closure, produces a reasonably accurate solution with minimal computational overhead.

Comparison of 1D, coupled 1D–2D, and 2D shallow water numerical modeling for dam-break flow analysis of Way-Ela dam, Indonesia

This study analyzes the flood inundation area using shallow water numerical modeling with HEC-RAS 6.3 software by comparing 1D, coupled 1D–2D, and 2D approaches. As a case study, the 2013 Way-Ela dam-break event in Indonesia is selected. Way-Ela Dam naturally formed by landslides in 2012, collapsed due to a piping mechanism after a heavy rainfall event. To estimate the breach outflow hydrograph, an empirical parametric model based on regression formula is used. Compared with the observed data, the numerical results show the 2D model produces the most accurate results among others, with reasonable computational time, while the 1D model, despite being computationally very efficient, misinterprets the flood extent map. The coupled 1D–2D model produces results similar to that of the 2D model; however, this coupled approach, which is expected to be more computationally efficient than the 2D one, interestingly yields a significantly longer calculation time. Some possible reasons are thus discussed. Additionally, comparisons for the water level and velocity are also presented in several locations to point out the difference between each model. Our finding informs the selection of an appropriate hydrodynamic model for dam-break simulations, balancing the result accuracy and computational cost.

Well-Balanced conservative central upwind scheme for solving the dam-break flow problem over erodible bed

This work deals with the numerical solution of dam-break flow over an erodible bed. The mathematical model is a combination of the shallow water, the transport diffusion and the bed morphology change equations. The system is solved by a well-Balanced central upwind scheme with conservative property. Several tests are illustrated in order to validate the accuracy and the performance of the model. A comparison of central upwind scheme and Roe scheme is presented.

Numerical simulations of dam-break flows of viscoplastic fluids via shallow water equations

This paper presents simulations of dam-break flows of Herschel–Bulkley viscoplastic fluids over complex topographies using the shallow water equations (SWE). In particular, this study aims to assess the effects of rheological parameters: power-law index (n), consistency index (K), and yield stress (τc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au _{c}$$\\end{document}), on flow height and velocity over different topographies. Three practical examples of dam-break flow cases are considered: a dam-break on an inclined flat surface, a dam-break over a non-flat topography, and a dam-break over a wet bed (downstream containing an initial fluid level). The effects of bed slope and depth ratios (the ratio between upstream and downstream fluid levels) on flow behaviour are also analyzed. The numerical results are compared with experimental data from the literature and are found to be in good agreement. Results show that for both dry and wet bed conditions, the fluid front position, peak height, and mean velocity decrease when any of the three rheological parameters are increased. However, based on a parametric sensitivity analysis, the power-law index appears to be the dominant factor in dictating fluid behaviour. Moreover, by increasing the bed slope and/or depth ratio, the wave-frontal position moves further downstream. Furthermore, the presence of an obstacle is observed to cause the formation of an upsurge that moves in the upstream direction, which increases by increasing any of the three rheological parameters. This study is useful for an in-depth understanding of the effects of rheology on catastrophic gravity-driven flows of non-Newtonian fluids (like lava or mud flows) for risk assessment and mitigation.Graphical abstract

Modelling and Impact Analysis of Combined Dam Failure of Small Tandem Reservoir Groups in Hilly Areas

Numerous small reservoirs in hilly areas play a significant role in flood control and profit-making in the basin, but there is also a risk of dam failure when encountering special circumstances such as excessive flooding, which may cause large losses downstream. In this paper, we take the small reservoirs in Shandong Province as the research object, analyze the hydraulic topology of three types of tandem reservoirs, generalize the shape of the breach by using the transient lateral local one-break to the end, calculate the dam-break flooding process by using the quadratic parabolic method, and simulate the dam-break by using the MIKE21 model based on the principle of the two-dimensional incompressible Reynolds mean stress equation for the incompressible fluid, and analyze the peak flow under various combinations of dam-break flow by setting various combinations of the number of dam-breaks and the timing of dam-break simulation. By setting various combinations of dam failure numbers and timing, we analyzed the changing rules of peak dam failure flow, inundation area and other elements under various combinations, and sought the most unfavorable combinations and parameters such as the timing of dam failure, and the results of the analyses can provide technical support for the assessment of the risk of dam failure in the tandem reservoirs in the hilly area and the risk correspondence.

Spatio-temporal water height prediction for dam break flows using deep learning

Spatio-temporal prediction of the water height for dam break flow is of great significance in flood control projects. In this article, we propose a novel deep learning model named AE-LSTM-ATT that combines AutoEncoder (AE) and Long Short-Term Memory with Attention (LSTM-ATT) to predict the dynamic behavior of the dam-break water height field in spatial and temporal dimensions. The prediction performance of the AE-LSTM-ATT model was demonstrated using dam-break flow cases with different initial heights of the water column. The AE first compresses high-dimensional inputs into low-dimensional latent space using its encoder to enable a fast computation process. Then, the latent space is adopted as an input for the LSTM-ATT to predict low-dimensional representations at future time instances that can be restored to the water height field by the decoder of the AE. The major findings of this article include three parts: (1) AE-LSTM-ATT model can successfully achieve the spatio-temporal prediction of the water height for dam break flows with high precision; (2) The proposed AE presents much better performance than those of the widely used Principal Component Analysis (PCA) and Kernel Principal Component Analysis (KPCA) in the dimension reduction; (3) The developed LSTM-ATT performs far better than the commonly used Recurrent Neural Network (RNN) and Long Short-Term Memory (LSTM) in the time-series prediction. These promising results suggest that the proposed AE-LSTM-ATT model can play an essential role in capturing and advancing the spatio-temporal features of dam-break water height, which can be applied in the field of real-time decision making for dam-break floods.

Experimental study on flow kinematics of breaking wave impinging and overtopping on a deck structure

The present study experimentally investigates the flow kinematics due to breaking waves impinging and overtopping on a simplified deck structure. Several breaking-wave impinging scenarios in relation to the model deck are conducted. The resulting flow velocities in the aerated regions are measured using bubble image velocimetry (BIV). A wave focusing method is employed to generate plunging breakers. Repeated measurements are performed to obtain mean flow and turbulence characteristics. Two distinguished flow behaviors are observed among all seven scenarios. For the cases of a fully developed plunging breaker interacting with the deck structure, the maximum horizontal velocities above and below the structure are both around 1.2C, with C being the phase speed of the breaking wave; for the cases of a non-fully-developed plunging breaker impingement, the flow velocity below the deck is surprisingly large, with a value of 1.8C below the deck against 1.2C above the deck. Furthermore, the use of a dam-break flow to model the overtopping horizontal velocities on the deck is performed with satisfactory agreements for all the impinging scenarios. Moreover, the temporal and spatial varying prediction equation proposed by Ryu et al. (2007b) is used to model overtopping flow velocities, showing the applicability of this simplified methodology.