Kinematic Wave Research Articles

Kinematic-wave analysis of particle settling in tube centrifuges

The kinematic-wave theory of particle settling in tube centrifuges has become a subject of scientific discussion. Specifically, the common assumption was made that the flow in a rotating tube of large length/diameter ratio can be treated in one-dimensional approximation. The respective results have been found in agreement with measurements. However, an analysis of the two-dimensional settling process performed in the limit of vanishing particle concentration led to some results that are not in accordance with the one-dimensional flow approximation, irrespective of the length/diameter ratio. It is the aim of the present investigation to gain a better understanding of the process. According to the analysis presented here, quasi-one-dimensional kinematic waves are embedded in a two-dimensional bulk flow that is governed by the continuity equation for the mixture plus the boundary conditions at the walls of the tube. The results based on simplification assumptions are compared with those of the one-dimensional flow approximation. Limiting cases, based on an elaborate analysis of three distinct settling models, are investigated analytically, and the plausibility of some of the respective results is evaluated also in the context of the one-dimensional approximation. Experimental observations, reported in the time span 2001 through 2008, are compared with analytical results obtained and presented. Further experimental work beyond this time span is also analyzed.

Using soil hydromorphy degree for adjusting steady-state water table simulations along catenas in semiarid Russia

Mapping soil properties has obvious utility for formulating agricultural management regimes. One that is particularly pertinent in areas with shallow water tables in semiarid regions, especially where catchments have both dry and moist parts, is hydromorphy degree. However, there is no convenient method for converting it to hydrological model state variables, which is a crucial first step for mapping (in the absence of extremely thorough and costly monitoring). Here we propose that the steady state continuity equation in kinematic wave form can be parameterized using expert knowledge of the typical water table depth (WTD) for soils with different hydromorphy degrees. To test the approach, six hillslope-based computational units (catenas) were obtained, for use in simulations, by automated of the Samovetc and Izberdey catchments in the Tambov region (Russia) using lumpR software. Five of the six catenas began at poorly drained flat upslope positions with soils with various degrees of saturation by shallow groundwater and one began at a well-drained upslope position. Each of the six hillslopes had a unique catenary sequence of soils, but each represented a typical unit. We genetically classified soils in the sequences according to hydromorphy degree based on redoximorphic features as diagnostic properties. For each resulting group, a historical database summarizing possible positions of the WTD was used. Application of expert knowledge in this manner alone yielded a broad range of possible WTD values (e.g. 1.5–5 m for a semi-hydromorphic soil) for each soil entity, but linking a catena by the fundamental physical constraint of flow continuity enabled narrowing of the range to 0.2–1 m thereby reducing it by ca. 80%. The results show that the approach could substantially improve crop and water management precision.

Mathematical modelling of bottom deformations in the kinematic wave approximation

Two possible approaches for generalizing the kinematic wave model for deformable channels are being discussed in this paper, including the approximation in which the law of conservation of fluid mass includes erosion and sedimentation; and approximation that the fluid flow is determined by the kinematic wave equation without taking into account bottom deformations.Systematic comparison of the results of calculations of self-similar waves for different values of the change in water flow was carried out as well.

Perspective: Preferential Flow in Riparian Buffers: Current Research and Future Needs

HighlightsPreferential flow (PF) can critically reduce riparian buffer contaminant removal efficiency.This collection presents research on PF measurement, visualization, modeling, and contaminant transport impacts.Future needs include tools to identify landscape-scale PF areas and conservation practices.Future models for research and practice should account for PF in riparian buffers.Abstract. Preferential flow in riparian buffers can substantially compromise their effectiveness in reducing contaminants from overland runoff. The objective of this article is to introduce a collection of five articles on current research into subsurface preferential flow measurement, visualization, modeling, and impacts on contaminant fate and transport at scales ranging from the subsurface pore scale to the plot scale to the watershed scale. This collection presents selected works from a broader invited session on “Preferential flow and piping in riparian buffers” at the 2020 ASABE Annual International Meeting. Major findings include: new methodologies, such as light transmission and geophysics, to characterize subsurface preferential flow; an infiltration partitioning approach to quantify preferential flow from field experiments; a kinematic dispersive wave model to effectively simulate subsurface preferential flow; and the significant impact of surface concentrated flow pathways on pesticide fate and transport both upstream and within a riparian buffer. Future work is needed to develop methods and tools to identify PF areas and management solutions within a landscape, and to update both research and design models to better quantify and account for PF processes. Keywords: Best management practice, Buffer strip, Agricultural conservation practice, Filter strip, Macropore, Nonpoint-source pollution.

Hydraulic modeling of combined sewers overflow integrating the results of the SWMM and CFX models.

This study proposes a methodology for the calibration of combined sewer overflow (CSO), incorporating the results of the three-dimensional ANSYS CFX model in the SWMM one-dimensional model. The procedure consists of constructing calibration curves in ANSYS CFX that relate the input flow to the CSO with the overflow, to then incorporate them into the SWMM model. The results obtained show that the behavior of the flow over the crest of the overflow weir varies in space and time. Therefore, the flow of entry to the CSO and the flow of excesses maintain a non-linear relationship, contrary to the results obtained in the one-dimensional model. However, the uncertainty associated with the idealization of flow methodologies in one dimension is reduced under the SWMM model with kinematic wave conditions and simulating CSO from curves obtained in ANSYS CFX. The result obtained facilitates the calibration of combined sewer networks for permanent or non-permanent flow conditions, by means of the construction of curves in a three-dimensional model, especially when the information collected in situ is limited.

Flow feasibility condition analysis and design optimization of contraflow left-turn lanes at signalized intersections based on kinematic wave theory

Dynamic left turning using lanes exiting an intersection in the opposite direction is a new type of left-turn traffic organization. When the left-turn traffic volume at an intersection is large, several exiting lanes adjacent to the original left-turn lanes can be converted into left-turn lanes during a certain period of free time under the control of a presignal. Based on kinematic wave theory, this paper analyzes the spatiotemporal process of the left-turn traffic flow. Three cases are analyzed, and the corresponding flow feasibility constraints are obtained in the form of requirements on the length of the contraflow left-turn lane and the coordination between the main signal and the presignal. Optimization of the lane length and signal coordination to maximize the number of vehicles entering the contraflow left-turn lane while guaranteeing traffic flow safety is discussed, and a practical example is analyzed.

ПОДВИЖКИ ЛЕДНИКОВ ПАМИРА В 2020 ГОДУ

Every year, about ten glaciers in the Western Pamirs are in the active stage of movement. The time from the beginning of the movement of kinematic waves along the glacier to the full completion of the pulsation takes, as a rule, 1– 2 years, and in some cases lasts up to 5 years. Activity of the Pamir glaciers in 2020 is discussed in this paper, and we suppose that some pulsations are still in progress in the following years. Data from a number of automatic satellite instruments were used for the analysis, but mainly these were obtained from the International Space Station. In 2020, 10 glaciers in the basins of the Surkhob, Muksu, Seldara, Kyzylsu and Vanch rivers became more active, and in some cases surged. Similar dynamic instability of glaciers was also characteristic for the preceding four years. At present, several major surges are taking place in the Western Pamirs; the Byrs, Vali, Lenin, and Medvezhy glaciers started the active phase of their developments. Therefore, it is necessary to study them by field methods and continue permanent monitoring of them from automatic satellites and the International Space Station.

Effect of Material Parameter of Viscoelastic Giesekus Fluids on Extensional Properties in Spinline and Draw Resonance Instability in Isothermal Melt Spinning Process.

The draw resonance instability of viscoelastic Giesekus fluids was studied by correlating the spinline extensional features and transit times of several kinematic waves in an isothermal melt spinning process. The critical drawdown ratios were critically dependent on the Deborah number (De, the ratio of material relaxation time to process time) and a single material parameter () of the Giesekus fluid. In the intermediate range of , the stability status changed distinctively with increasing De, i.e., the spinning system was initially stabilized and subsequently destabilized, as De increases. In this regime, the level of velocity and extensional-thickening rheological property in the spinline became gradually enhanced at low De and weakened at high De. The draw resonance onsets for different values of were determined precisely using a simple indicator composed of several kinematic waves traveling the entire spinline and period of oscillation. The change in transit times of kinematic waves for varying De adequately reflected the effect of on the change in stability.

Channel Profile Response to Abrupt Increases in Mountain Uplift Rates: Implications for Late Miocene to Pliocene Acceleration of Intracontinental Extension in the Northern Qinling Range-Weihe Graben, Central China

Abstract Cenozoic extension of the Qinling range-Weihe Graben system has occurred in response to the uplift and growth of the Tibetan Plateau. Rapid exhumation of the northern Qinling range since the late Miocene is also regarded as resulting from the eastward expansion of the northeast part of Tibet. Tectonic evidence of this in the landscape remains unclear, but the fluvial system can provide a sensitive proxy record of tectonic forcing through space and over time scales of 105–107 a. Here, we present a study of channel profiles in the northern Qinling range, which forms a footwall highland separated from the southern Weihe Graben by active normal faults. We identify a population of knickpoints that separate river profiles with a gentle upstream gradient from steeper downstream reaches. Above the knickpoints, steepness indices increase from the central part towards the west and east, whereas channel steepness shows its highest values in the Huaxian-Huayin section. We observed no systematic changes of channel steepness pattern as a function of rock resistance, drainage area, or channel concavity. Correlation analysis between channel steepness and basin elevation and relief documents the control of tectonic forcing on regional topography. While bearing no relation to geological outcrop boundaries, the knickpoints show a strong correlation between retreat distance, catchment area, and river length. We infer that the knickpoints formed in response to an increase in mountain uplift rates and retreated as a kinematic wave. Under linear slope exponent n, we calibrated channel erodibility K~1.00±0.44×10−6 m0.1/a and derived knickpoint ages of 5.59±1.80 Ma. Combining the ages of onset of active faulting and mountain growth in the NE Tibetan Plateau (8–10 Ma, e.g., Liupan Shan, Jishi Shan, and eastern segments of the Haiyuan and Kunlun faults) and in the southwest Qinling range (9–4 Ma), we conclude that growth of the NE Tibetan Plateau began in the mid-Miocene time and expanded eastwards to the Qinling range-Weihe Graben during the late Miocene and early Pliocene.

Spatiotemporal filtering method for detecting kinematic waves in a connected environment.

Backward-moving kinematic waves (KWs) (e.g., stop-and-go traffic conditions and a shock wave) cause unsafe driving conditions, decreases in the capacities of freeways, and increased travel time. In this paper, a sequential filtering method is proposed to detect KWs using data collected in a connected environment, which can aid in developing a traffic control strategy for connected vehicles to stop or dampen the propagation of these KWs. The proposed method filters out random fluctuation in the data using ensemble empirical mode decomposition that considers the spectral features of KWs. Then, the spatial movements of KWs are considered using cross-correlation to identify potential candidate KWs. Asynchronous changes in the denoised flow and speed are used to evaluate candidate KWs using logistic regression to identify the KWs from localized reductions in speed that are not propagated upstream. The findings from an empirical evaluation of the proposed method showed strong promise for detecting KWs using data in a connected environment, even at 30% of the market penetration rates. This paper also addresses how data resolution of the connected environment affects the performance in detecting KWs.

Surface-wave instability without inertia in shear-thickening suspensions

Recent simulations and experiments have shown that shear-thickening of dense particle suspensions corresponds to a frictional transition. Based on this understanding, non-monotonic rheological laws have been proposed and successfully tested in rheometers. These recent advances offer a unique opportunity for moving beyond rheometry and tackling quantitatively hydrodynamic flows of shear-thickening suspensions. Here, we investigate the flow of a shear-thickening suspension down an inclined plane and show that, at large volume fractions, surface kinematic waves can spontaneously emerge. Curiously, the instability develops at low Reynolds numbers, and therefore does not fit into the classical framework of Kapitza or ‘roll-waves’ instabilities based on inertia. We show that this instability, that we call ‘Oobleck waves’, arises from the sole coupling between the non-monotonic (S-shape) rheological laws of shear-thickening suspensions and the flow free surface.

Investigation of Flood Routing Using Variable Parameter Kinematic Wave Model (VPKWM) for Non-Prismatic Natural Channel in an Ungauged Basin

Abstract This research concerns about the development and application of Variable Parameter Kinematic Wave Numerical model (VPKWM) based on 1-D Saint-Venant equation, to study the behaviour of the propagation of a flood wave in Non-prismatic natural waterways in an ungauged basin. The channel slope and wetted perimeter are considered as variable because of the irregularity of the boundary of the channel and the change in magnitude of discharge. The scarcity of reliable inflow data at upstream is a serious problem for the flood routing process in an ungauged basin. In this study the inflow hydrograph and lateral inflow hydrographs are obtained using SCS-CN method as rainfall runoff model. The performance of the model assessed considering four parameters such as root mean square error (RMSE), peak discharge, peak time and total volume. The results indicated that the VPKWM for non-prismatic channel provided reasonable output compared with the observed data.

Modelling of the Complex Groundwater Level Dynamics during Episodic Rainfall Events of a Surficial Aquifer in Southern Italy

We analyzed the complex dynamics that are involved the groundwater level variations due to the episodic rainfall supply in the Ionian coastal plain surficial aquifer located in Southern Italy. In this aquifer, as a consequence of the particular hydrogeological framework, both direct and lateral recharge mechanisms coexist. Hence, the dynamics of groundwater level variations are quite complex and strongly non-linear. Our focus was essentially on the short-term behavior of groundwater levels, with a specific analysis on episodic rainfall events. To model these dynamics, due to the presence of the preferential pathways in the infiltration processes, a kinematic dispersion wave model was used. Specifically, a one-dimensional and non-linear particle-based numerical model was developed. It uses ideal particles with constant water volume travel, according to celerity and hydraulic dispersion, to simulate the infiltration rate wave through the vadose zone. The infiltration rate that reaches the water table represents the input function to evaluate the aquifer groundwater level fluctuations. As a consequence of the special lithological and storage capacity characteristics of the surficial layers, groundwater flow conditions change from unconfined to confined. The developed model analyzes the direct groundwater supply under natural conditions, including episodic rainfall, and it has been validated using a high-resolution time series of rainfall data and groundwater level obtained from the monitoring station Terra Montonata.

The Ensemble Framework For Flash Flood Forecasting (EF5) v1.2: description and case study

Abstract. The Ensemble Framework For Flash Flood Forecasting (EF5) was developed specifically for improving hydrologic predictions to aid in the issuance of flash flood warnings by the US National Weather Service. EF5 features multiple water balance models and two routing schemes which can be used to generate ensemble forecasts of streamflow, streamflow normalized by upstream basin area (i.e., unit streamflow), and soil saturation. EF5 is designed to utilize high-resolution precipitation forcing datasets now available in real time. A study on flash-flood-scale basins was conducted over the conterminous United States using gauged basins with catchment areas less than 1000 km2. The results of the study show that the three uncalibrated water balance models linked to kinematic wave routing are skillful in simulating streamflow.

Analytical solutions to runoff on hillslopes with curvature: numerical and laboratory verification

AbstractPredicting the behavior of overland flow with analytical solutions to the kinematic wave equation is appealing due to its relative ease of implementation. Such simple solutions, however, have largely been constrained to applications on simple planar hillslopes. This study presents analytical solutions to the kinematic wave equation for hillslopes with modest topographic curvature that causes divergence or convergence of runoff flowpaths. The solution averages flow depths along changing hillslope contours whose lengths vary according hillslope width function, and results in a one‐dimensional approximation to the two‐dimensional flow field. The solutions are tested against both two‐dimensional numerical solutions to the kinematic wave equation (in ParFlow) and against experiments that use rainfall simulation on machined hillslopes with defined curvature properties. Excellent agreement between numerical, experimental and analytical solutions is found for hillslopes with mild to moderate curvature. The solutions show that curvature drives large changes in maximum flow rate qpeak and time of concentration tc, predictions frequently used in engineering hydrologic design and analysis.

Addition of overland runoff and flow routing methods to SWMM-model application to Hyderabad, India.

Hydrological models apply different methods to estimate runoff and route flows. Suitability of these methods is not unique, but varies with catchment conditions. This study aims to find the suitable overland runoff and flow routing methods for a catchment in Hyderabad, India, using customised Storm Water Management Model (SWMM-C). Currently, SWMM adapts only non-linear reservoir (NLR) method to estimate overland runoff. Linear reservoir (LR) and kinematic wave overland flow (KWO) have been incorporated as additional overland runoff methods. For flow routing, SWMM currently has kinematic wave (KW) and dynamic wave (DW) methods. Muskingum, Muskingum Cunge (MC) and lag methods have been included as additional methods in this customised version. SWMM-C was calibrated with four event rainfalls and tested with six event rainfalls using all possible combinations of overland runoff and flow routing methods. Efficiency of SWMM-C in simulating runoff was evaluated using performance indices. Results showed that for low magnitude event rainfalls, NLR, LR and KWO simulated runoff with a maximum deviation of 50%, 60% and 40% from observed runoff, respectively. In high magnitude event rainfalls, NLR, LR and KWO simulated runoff with maximum deviations of 20%, 40% and 20%, respectively, from the observed runoff. It was inferred from model outputs that NLR method could simulate runoff reasonably well for rainfalls that have duration greater than the time of concentration of catchment. LR method could simulate peak runoff better. KWO method was found to be suitable for chosen catchment for all rainfall durations. Flow routing methods KW, DW and MC are found to have minor influences on the runoff.

Applicability of Kinematic Wave Model for Flood Routing under Unsteady Inflow

This study implemented kinematic wave and dynamic wave approximation of flood routing for a prismatic rectangular channel. The results of the two methods were compared by differences in maximum flow depth, and the applicability of kinematic wave equation was discussed. The influences of hydraulic and geometrical factors on the applicability of kinematic wave equation were considered. It was found that a portion of the numerical results violated existing criteria used to indicate the applicability of kinematic wave equation, particularly when geometrical and hydraulic factors were considered together. This is because the characteristics of upstream inflow were rarely or incompletely considered in these criteria. Therefore, the present study proposed a new criterion. The theoretical influence of all factors was considered using three parameters, namely, KF02, ηts/T0′ and Qbottom/Qpeak (K, F0, ηts, T0′, Qbottom, and Qpeak represent the kinematic wave number, Froude number, the time span of discharge exceeding 90% of maximum discharge in hydrograph, wave travel time in the channel, base flow discharge, and peak discharge, respectively, while the subscript 0 represent the value of reference discharge). The influences of these three parameters were illustrated by the momentum equation of one-dimensional Saint-Venant equation. The numerical results showed that the value of ηts/T0′ (KF02)D could be used to determine the relative error ξh of kinematic wave equation. In addition, for each Qbottom/Qpeak the value of ηts/T0′ (KF02)D used to depict the same relative error ξh was different. This new criterion was validated using two real case studies, and it showed a good performance.

Intermittent slug flow identification and characterization from pressure signature

Despite of its occurrence in several industrial applications, it remains an open issue to accurately predict the behavior of multiphase flow. More specifically, when direct observation of the flow is not possible, which typically occurs in the petroleum industry, indirect methods of identifying main features of the flow are necessary. In this paper, we propose a method for the determination of some important parameters in two-phase gas–liquid flow, the velocity in situ of the Taylor Bubble, using differential pressure measurements. This is done through the analysis of the time and frequency signature of a normalized signal and its coupling with void fraction waves. A phase difference estimator based on the cross-spectra between differential pressure signals is proposed. It is experimentally shown that there is a region of the spectrum where the differential pressure signals and the void fraction kinematic waves are coupled. Besides, a relation between the differential pressure signals and the void fraction wave is established, allowing to discuss the underlying physics of the two-phase flow and then determining the Taylor bubble velocity. In this paper, results are shown for intermittent slug flow only, but the proposed approach can potentially be extended to different flow patterns. The presented results show that the use of differential pressure measurements related to void fraction waves have the potential of becoming a methodology applicable by the industry as a tool to identify and characterize flow patterns.

Vadose Zone Lag Time Effect on Groundwater Drought in a Temperate Climate

An essential factor in the propagation of drought, from meteorological drought to groundwater drought, is the delay between a precipitation event and the groundwater recharge reaching the groundwater table. This delay, which mainly occurs in the vadose zone of the hydrological cycle, is often poorly studied. Therefore, this paper proposes a method for estimating the spatially distributed delay in the vadose zone using the kinematic wave approximation of Richards’ equation combined with the van Genuchten–Burdine and Brooks–Corey parametric model. The modeling was approached (1) using a detailed parametrization of soil and geological layers and (2) using lumped hydraulic and physical properties of geological layers. The results of both approaches were compared against the physically based flow model Hydrus-1D. This analysis shows that using a detailed parametrization of soil and geological layers results in good comparison, with a Nash–Sutcliffe efficiency of 0.89 for Brooks–Corey and 0.80 for van Genuchten–Burdine. The delay result of the Brooks–Corey model was incorporated into the groundwater recharge time series from 1980 to 2013 to analyze the effect of this delay on groundwater drought. The results show that the delay in the vadose zone influences groundwater drought characterization features such as the number, duration, and intensity of drought events.

Identification of Parameters Influencing the Accuracy of the Solution of the Nonlinear Muskingum Equation

Two nonlinear versions of the Muskingum equation are considered. The difference between both equations relates to the exponent parameter. In the first version, commonly used in hydrology, this parameter is considered as free, while in the second version, it takes a value resulting from the kinematic wave theory. Consequently, the first version of the equation is dimensionally inconsistent, whereas the proposed second one is consistent. It is shown that the difference between the results provided by both versions of the nonlinear Muskingum equation depends on the longitudinal bed slope of a channel. For an increasing slope, when a propagating wave becomes more kinematic, the value of the exponent considered as the free parameter tends to its value resulting from the kinematic wave theory. Consequently, when the character of an open channel flow tends to a kinematic one, the dimensionally inconsistent version of the nonlinear Muskingum equation becomes a consistent one. The results of the numerical analysis suggest that apart from the parameters involved in the Muskingum equation, usually considered as free, the parameters of the numerical method of the solution (the number of reservoirs and the time step) should be considered also as free parameters. This conclusion results from the fundamental property of the Muskingum equation, relating to the numerical roots of the wave attenuation process. All numerical examples and tests relate to the solutions of the system of Saint Venant equations, considered as the benchmark.