Acoustic Doppler Velocity Meter Research Articles

Analysis of the Capacity of a Double Rating Curve to Reproduce the Flows Measured by Doppler Fixed at the Bottom of an Ice Covered River

The classic approach for estimating river flows is based on the use of a rating curve, which links the flow rates to the water heights measured at a gauging station. This simple approach, has practical and economic advantages but also has limitations related in part to the difficulty of obtaining a representative range of flows, particularly in the presence of ice cover. The objective of this study is to show how it is possible to improve the results obtained by a traditional rating curve using the validated measurements of the Acoustic Doppler Velocity Meter (ADVM) of the Argonaut SW (shallow water) Doppler obtained in continuous, in the presence of ice sheet. The proposed methodology consists in filtering and validating the height measurements provided by the standard gauge as well as the speed and height the measurements provided by the Doppler SW. The validated measurements are then split into two parts: The first part is used for the calibration of a double rating curve that links the series of validated levels obtained by the standard limnimeter, to the flow obtained from the Doppler SW. The second part is used to evaluate the capacity of the double rating curve obtained during the calibration, and to estimate the flow measured by the Doppler SW. The double rating curve thus calibrated reproduces the flow measured by the Doppler SW with an average deviation of 5.03%. In the presence of ice cover, this average difference is 7.68%. These results show the interest of a combined use of the Doppler SW and the double rating curve, for monitoring river flows under ice cover. The Doppler SW makes data available, necessary to calibrate a reliable rating curve, based on a wide range of flow variations covering the winter period.

Application of Stage-Fall-Discharge Rating Curves to a Reservoir Based on Acoustic Doppler Velocity Meter Measurement Data

The applicability of the stage-fall-discharge (SFD) method in combination with acoustic Doppler velocity meter (ADVM) data, upstream of a hydraulic structure, specifically, the Sejong-weir located in the Geum River, Korea, was examined. We developed three rating curves: a conventional simple rating curve with the data measured using an acoustic Doppler current profiler (ADCP) and floating objects, an SFD rating curve with the data measured using the ADCP and floating objects, and an SFD rating curve with the data measured using an ADVM. Because of the gate operation effect, every rating curve involved many uncertainties under 1000 m3/s (3.13 m2/s, specific discharge). In terms of the hydrograph reconstruction, compared with the conventional simple rating curve, the SFD developed using ADVM data exhibited a higher agreement with the measured data in terms of the pattern. Furthermore, the measured discharge over 1000 m3/s primarily ranged between 97.5% and 2.5% in the graph comparing the ratio of the median and observed discharge. Based on this experiment, it is confirmed that the SFD rating curve with data to represent the backwater effect, such as ADVM data, can reduce the uncertainties induced by the typical rating curve

Deep-sea <i>in-situ</i> laser Doppler velocity measurement system

A set of 4000-meter laser Doppler hydrothermal velocity measurement prototype suitable for deep sea <i>in-situ</i> measurement is developed in this work. In the system, an integrated design is adopted. The system is composed of a light source module, an optical module, and a Doppler signal processing module. The system is encapsulated in a pressure chamber with <i>L</i>500 mm × <i>Φ</i>205 mm to form an integrated optical measuring probe. An optical path of two-beam laser Doppler velocity measurement with strong local oscillator is proposed. The prototype is used to measure the simulated velocity in the laboratory. The measurement range is 0.01–10 m/s, and the flow velocity measurement resolution is 0.001 m/s. The experimental results preliminarily prove the feasibility of the laser Doppler velocity measurement system. After that, a withstanding voltage test on the system is conducted at the Qingdao Deep Sea Base, and the system obtains a normal signal under a high pressure of 40 MPa. A speed comparison measurement is carried out at the China Institute of Water Resources and Hydropower Research. In a low speed range from 0.01 m/s to 0.2 m/s, comparing with the acoustic Doppler velocity meter, the maximum measurement relative error is –9.43%. In a high speed range from 0.8 m/s to 9.6 m/s, comparing with the nozzle standard flow rate system, the maximum relative measurement error is –1.65%. The prototype system is tested in a shallow sea in Lingshui, Hainan. The sinking speed of the prototype system that sinks together with a crane down to a water depth of 50 m, and the towing speed of the system together with the ship at a depth of 2 m are tested. The test proves that the prototype system works normally in a shallow sea environment.

Denoising and despiking ADV velocity and salinity concentration data in turbulent stratified flows

Due to the presence of noise and spikes in velocity measurements of turbulent flow fields, understanding the flow pattern may be seriously affected by the spurious values for zones where certain flow behaviour is not necessarily expected. In a series of laboratory experiments the velocity data recorded, using Acoustic Doppler Velocity meters (ADVs), and the salinity measurements were noticeably noisy. In despiking and denoising the velocity data a linear correlation algorithm was established, which successfully lowered the noise levels and removed the spikes. For the assessment of the method, an autoregressive model was used to generate a clean velocity signal. The spikes were generated with a uniformly random time index and a Gaussian distributed value, where White Gaussian noise was added to this simulated signal. Assessment was also undertaken on the signals generated using a three-dimensional numerical model. To enhance the comprehension of the flow field, an interpolation method for producing the missing data has also been developed, which may be deployed to increase the sampling frequency, or to produce data for the spatial domain at locations which are not included in the measurements. For salinity a different strategy was applied where a moving average procedure was carried out, as the data did not suffer from spikes and exhibited almost a constant band of noisy fluctuations.

Enhancing PIV image and fractal descriptor for velocity and shear stresses propagation around a circular pier

In this study, the fractal dimensions of velocity fluctuations and the Reynolds shear stresses propagation for flow around a circular bridge pier are presented. In the study reported herein, the fractal dimension of velocity fluctuations (u′, v′, w′) and the Reynolds shear stresses (u′v′ and u′w′) of flow around a bridge pier were computed using a Fractal Interpolation Function (FIF) algorithm. The velocity fluctuations of flow along a horizontal plane above the bed were measured using Acoustic Doppler Velocity meter (ADV) and Particle Image Velocimetry (PIV). The PIV is a powerful technique which enables us to attain high resolution spatial and temporal information of turbulent flow using instantaneous time snapshots. In this study, PIV was used for detection of high resolution fractal scaling around a bridge pier. The results showed that the fractal dimension of flow fluctuated significantly in the longitudinal and transverse directions in the vicinity of the pier. It was also found that the fractal dimension of velocity fluctuations and shear stresses increased rapidly at vicinity of pier at downstream whereas it remained approximately unchanged far downstream of the pier. The higher value of fractal dimension was found at a distance equal to one times of the pier diameter in the back of the pier. Furthermore, the average fractal dimension for the streamwise and transverse velocity fluctuations decreased from the centreline to the side wall of the flume. Finally, the results from ADV measurement were consistent with the result from PIV, therefore, the ADV enables to detect turbulent characteristics of flow around a circular bridge pier.

Entrainment, retention, and transport of freely swimming fish in junction gaps between commercial barges operating on the Illinois Waterway

Abstract Large Electric Dispersal Barriers were constructed in the Chicago Sanitary and Ship Canal (CSSC) to prevent the transfer of invasive fish species between the Mississippi River Basin and the Great Lakes Basin while simultaneously allowing the passage of commercial barge traffic. We investigated the potential for entrainment, retention, and transport of freely swimming fish within large gaps (> 50 m3) created at junction points between barges. Modified mark and capture trials were employed to assess fish entrainment, retention, and transport by barge tows. A multi-beam sonar system enabled estimation of fish abundance within barge junction gaps. Barges were also instrumented with acoustic Doppler velocity meters to map the velocity distribution in the water surrounding the barge and in the gap formed at the junction of two barges. Results indicate that the water inside the gap can move upstream with a barge tow at speeds near the barge tow travel speed. Water within 1 m to the side of the barge junction gaps was observed to move upstream with the barge tow. Observed transverse and vertical water velocities suggest pathways by which fish may potentially be entrained into barge junction gaps. Results of mark and capture trials provide direct evidence that small fish can become entrained by barges, retained within junction gaps, and transported over distances of at least 15.5 km. Fish entrained within the barge junction gap were retained in that space as the barge tow transited through locks and the Electric Dispersal Barriers, which would be expected to impede fish movement upstream.

Discharge and Nutrient Transport between Lakes in a Hydrologically Complex Area of Voyageurs National Park, Minnesota, 2010‐2012

AbstractAn acoustic Doppler velocity meter (ADVM) was deployed in the narrows between Namakan and Kabetogama Lakes in Voyageurs National Park, Minnesota, from November 3, 2010, through October 3, 2012. The ADVM can account for wind, seiche, and changing flow direction in hydrologically complex areas. The objectives were to (1) estimate discharge and document the direction of water flow, (2) assess whether specific conductance can be used to determine flow direction, and (3) document nutrient and chlorophyll a concentrations at the narrows. The discharge direction through the narrows was seasonal. Water generally flowed out of Kabetogama Lake and into Namakan Lake throughout the ice‐covered season. During spring, water flow was generally from Namakan Lake to Kabetogama Lake. During the summer and fall, the water flowed in both directions, affected in part by wind. Water flowed into Namakan Lake 70% of water year 2011 and 56% of water year 2012. Nutrient and chlorophyll a concentrations were highest during the summer months when water‐flow direction was unpredictable. The use of an ADVM was effective for assessing flow direction and provided flow direction under ice. The results indicated the eutrophic Kabetogama Lake may have a negative effect on the more pristine Namakan Lake. The results also provide data on the effects of the current water‐level management plan and may help determine if adjustments are necessary to help protect the aquatic ecosystem of Voyageurs National Park.

The Hysteresis and Shear Velocity in Unsteady Flows

The shear velocity is an important parameter in characterizing the shear at the boundary in open channels and there exist methods to estimate the shear velocity in steady flows, but the application and comparison of these methods to non-uniform unsteady flows is limited. In this study, three artificial triangular-shaped hydrographs were generated where the base flow is non-uniform with fine sand bed and the shear velocity was obtained by the methods, u(*SV) by using the Saint-Venant equations, u(*L) by using the procedure given by Clauser Method, u(*P) by using the parabolic law, u(*UN) by using the momentum equation assuming the slope of energy grade line is equal to bed slope and u(*avg) by using the average velocity equation are used in this study. The stream-wise components of velocity time series and the velocity profiles were obtained by means of an acoustic Doppler velocity meter. The variation of the shear velocity and the constant for the parabolic law with time is discussed. It is concluded that the shear velocities found by the parabolic law and the average velocity equation can be used interchangeably. Furthermore a hysteresis intensity parameter is proposed in order to examine the depth variation of hysteretic behavior of depth variation both with point velocity and average velocity. It is revealed that the more the unsteady the hydrograph the more the hysteresis both in terms of point velocity and cross-sectional mean velocity.

Application of continuous wavelet transform to the study of large-scale coherent structures

It is generally recognized that large-scale turbulent coherent structures play an important role in the transport of sediment and contaminants in rivers. They are also believed to be related to the origin and development of a variety of fluvial bed and plan forms. While intensive laboratory and field research has been devoted in recent years to the study of large-scale vertical coherent structures, no such efforts have yet been directed to the study of large-scale horizontal coherent structures. This paper is intended as a contribution to address the existing lack of information on the latter structures. Its objective is to report an application of continuous wavelet transform (CWT) to the detection and establishment of the length and time scales of the largest coherent structures existing in a shallow open channel flow (width to depth ratio equal to 25), focusing primarily on the horizontal structures. The analysis is based on measurements of instantaneous flow velocity previously carried out in a 21 m long, 1 m wide flume. These include 306 single point velocity measurements collected throughout the flow field at a constant distance from the bed surface, the duration of each measurement being 120 s; and 20 min long measurements carried out at selected locations. The velocity was measured with the aid of a 2D Micro Acoustic Doppler Velocity meter. Large-scale horizontal coherent structures could be identified in all of the velocity records, and appeared as quasi-cyclic, sustained features in the flow. The intervals of time where such structures could not be detected were invariably short in comparison to the measurement time. CWT was found to be particularly well suited to determine the average time and length scales of the structures, two quantities of special significance in river morphodynamics. The average time scale of the large-scale horizontal structures for the investigated flow was found to be equal to 22.3 s, which implies a length scale of five times the flow width. Individual horizontal coherent structures with characteristic times approximately twice larger than the value of average time scale could be identified in the flow. However, these were infrequent occurrences in the flow.

Poisson 방정식을 이용한 유속분포법의 등속선 작성 및 적용

최근 우리나라에서는 이동시간차방식 초음파유속계(UVM; Ultrasonic Velocity Meter)나 도플러방식 초음파유속계(ADVM; Acoustic Doppler Velocity Meter)로 측정된 유속을 활용하여 하천유량을 산정하는 자동유량측정시설이 활발히 도입되고 있다. 하천유량을 산정하는 방법으로는 측정된 지표유속과 평균유속의 관계를 통해 흐름단면의 평균유속을 산정하는 지표유속법(IVM; Index Velocity Method), 일부 영역의 측정유속과 유속분포의 관계를 통해 흐름단면의 유속분포를 산정하는 유속분포법(VPM; Velocity Profile Method)이 있다. 유속분포법에 활용되고 있는 Chiu(1988)의 2차원 유속분포는 형상 매개변수가 많고 직사각형 이외의 흐름단면에서는 정확한 등속선 분포를 얻기가 곤란한 단점이 있다. 본 연구에서는 이러한 단점을 개선하기 위해 Poisson 방정식에 의한 유속분포법을 이론적 검토를 통해 제시하고, 한강 수계의 우만 지점과 한강대교 지점, 만경강 수계의 대천 지점에 적용하여 활용성을 검토하였다. Recently in Korea, automatic discharge measurement system which calculates the river discharge using velocity measured by UVM(Ultrasonic Velocity Meter) and ADVM(Acoustic Doppler Velocity Meter) is actively being introduced. There are IVM(Index Velocity Method) and VPM(Velocity Profile Method) in the method of calculating river discharge. IVM is the method of calculating mean velocity of the entire cross-section by establishing the relationship between index velocity and mean velocity and VPM is the method of calculating velocity distribution of the entire cross-section by establishing the relationship between index velocity and velocity distribution. Chiu(1988)'s 2-D velocity distribution using VPM, it is necessary to adjust a lot of shape parameter and it is difficult to obtain the exact isovel distribution except for the rectangular flow cross-section. In this study, we proposed the VPM by a theoretical review of the Poisson equation in order to improve the disadvantages of Chiu's method and verified the applicability by utilizing the velocity data of the automatic discharge measurement system, Wuman, Hangangdaegyo in the Han river and Daecheon in the Mangyung river.

Flow Characteristics of a Sharp-Crested Side Sluice Gate

AbstractThe side sluice gate is used in open channels to divert a part of flow to a side channel and to regulate the head of distributaries. In present study, the distribution of the three-dimensional velocity in the vicinity of the side sluice gate was obtained using an acoustic Doppler velocity meter (ADV). The structure of each component of velocity was separately examined. The velocity distributions indicated that longitudinal velocity peaks near the beginning of the side gate, whereas velocity in the direction of side channel and vertical velocity are highest at the middle of the side gate. In the vicinity of the side gate, the direction of the vertical velocity is downward. In the section area of the side gate, the diversion angle of velocity vectors in the horizontal plane is increased with increasing the distance from the beginning of the side gate. It reaches to the maximum value at the end of the side gate.

3D Flow Velocity Pattern in a Circular Section Within River Reach: An Experimental Study

Circular sections utilize vortex flow within the chamber to separate sediment particles from the river flow. The structure of flow inside the circular basins is complicated and fully three-dimensional. In this paper, three-dimensional flow velocity was measured to understand the flow structure and to distinguish secondary currents above and below a deflector which was installed inside the basin. Within the vortex extractor, the variation of sediment concentration is greatly affected by variation in the velocity components, in vertical, radial and tangential directions of flow inside the basin. The three-dimensional flow velocity was measured using an Acoustic Doppler Velocity meter. The velocity of flow was measured at 448 different nodal points, at eight different layers within the flow depth. Of these 448 nodal points, 336 nodal points were below the deflector and 112 nodal points were above it. The measurements were taken at eight different degrees. From this study, it was found that the tangential velocity under a deflector decreases, compared to the tangential velocity in a vortex basin without a deflector, and as a result the secondary currents under a deflector also decrease. Furthermore, as the secondary currents under a deflector decrease, these currents approach the central orifice. Secondary currents under a deflector are useful to impinge deposited sediment particles towards the flushing orifice.

Three-dimensional analysis of coherent turbulent flow structure around a single circular bridge pier

The coherent turbulent flow around a single circular bridge pier and its effects on the bed scouring pattern is investigated in this study. The coherent turbulent flow and associated shear stresses play a major role in sediment entrainment from the bed particularly around a bridge pier where complex vortex structures exist. The conventional two-dimensional quadrant analysis of the bursting process is unable to define sediment entrainment, particularly where fully three-dimensional flow structures exist. In this paper, three-dimensional octant analysis was used to improve understanding of the role of bursting events in the process of particle entrainment. In this study, the three-dimensional velocity of flow was measured at 102 points near the bed of an open channel using an Acoustic Doppler Velocity meter (Micro-ADV). The pattern of bed scouring was measured during the experiment. The velocity data were analysed using the Markov process to investigate the sequential occurrence of bursting events and to determine the transition probability of the bursting events. The results showed that external sweep and internal ejection events were an effective mechanism for sediment entrainment around a single circular bridge pier. The results are useful in understanding scour patterns around bridge piers.

Three Dimensional Bursting Phenomena in Open Channel Bends

The turbulent coherent structure of flow in open channel bends is a stochastic process in nature. The coherence structure of the flow or bursting process is very important for the entrainment of sediment particles from the bed. In this study, first-order Markov process combined with three-dimensional quadrant analysis is applied to the measured turbulent data in open channel bends. The turbulent data was measured in an experimental flume using three-dimensional acoustic Doppler velocity meter (ADV). It was found that the stable movements of velocity fluctuations have higher transition probabilities than other movements, and the cross movements have the least transition probability. In addition, the internal group of events occurs more frequently than external group, particularly the internal ejection and internal sweep events and the probabilities decrease from the concave bank to the convex bank periodically, and reach the maximum at the top of the curved concave bank.

Three-Dimensional Turbulence Intensity in a Compound Channel

AbstractExperimental research was undertaken to investigate the changes in spatial turbulence intensity in a compound channel and the influence of rigid, emergent floodplain vegetation on turbulence intensity. Five tests for two various roughness values of floodplains were realized. In the first series of experiments (three tests), the surface of the main channel bed was smooth and made of concrete, whereas the floodplains and sloping banks were covered by cement mortar composed of terrazzo. In the second set of experiments (two tests), emergent vegetation (trees) on the floodplains, modeled by aluminum pipes, was added. Instantaneous velocities were measured with the use of a three-component acoustic Doppler velocity meter. The influence of floodplain trees, on the distributions of relative turbulence intensity (u′/U, v′/U, w′/U) in the main channel and on the floodplains was presented. It was found that the longitudinal (u′/U) and transverse (v′/U) turbulence values decreased from the bottom upward to t...

Rating Curve Pattern in a Compound Meandering Channel Flow

Most of the river flow in the world can be characterized as compound meandering channel in which the discharge distributions are very complex. Engineers, planners and researchers are highly interested in predicting accurately as well as reliably the quantitative estimates of discharge in a compound meandering channel. A laboratory experiment has been performed in a compound meandering channel with symmetric cross-sections having floodplain width ratio of 1.00, 1.67, 2.33, 3.00 and depth ratio of 0.20, 0.30, 0.35, 0.40 using the large-scale open air facility in the Department of Water Resources Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh. Point velocity data have been collected using an ADV (Acoustic Doppler Velocity meter) for different depth and width ratio at different locations of a compound meandering channel. Cross-sectional discharge is computed by area velocity method from the observation of velocity profile. The laboratory experiment shows that the rating curve pattern in a compound meandering channel follows the straight curve up to in bank flow and in the out bank flow it is in curvature nature.

An Experimental Study of Shear Stress Distribution in a Compound Meandering Channel

Naturally river flow can be characterized as compound meandering channel in which the shear stress characteristics are quite intricate. Reliable investigation of shear stress distribution in a compound meandering channel is essential in solving a variety of river hydraulics and engineering problems, designing stable channels and bank protection, understanding the mechanism of sediment transport. A laboratory experiment has been conducted in a compound meandering channel with symmetric cross-sections having floodplain width ratio of 1, 1.67, 2.33, 3 and depth ratio of 0.20, 0.30, 0.35, 0.40 using the large-scale open air facility in the Department of Water Resources Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh. Point velocity data have been collected using an ADV (Acoustic Doppler Velocity Meter) for different depth and width ratio at different locations of a compound meandering channel. Shear stress is calculated from the Prandtl-Von Karman Universal Velocity Distribution Law. The laboratory experimental investigation reveals that shear stress increases with the increase of depth and width ratio and low magnitude of boundary shear is observed in the outer bend as compare to the inner bend in a compound meandering channel.

An Experimental Study of Longitudinal Velocity Distribution at Cross-over and Bend Section of a Compound Meandering Channel

Generally, river flow can be schematized as compound meandering channel in which the longitudinal velocity distributions in the crossover and bend section are completely different and quite intricate. Engineers, Planners and Researchers are highly interested in predicting accurately as well as estimating quantitatively and reliably the longitudinal velocity distribution in a compound meandering channel. A laboratory experiment has been conducted in a compound meandering channel with symmetric cross-sections having floodplain width ratios (B/b) of 1.00, 1.67, 2.33, 3.00 and depth ratios (H-h)/h of 0.20, 0.30, 0.35, 0.40 using the large-scale open air facility in the Department of Water Resources Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka. Point velocity data have been collected using an ADV (Acoustic Doppler Velocity Meter) for different depth and width ratio at five different locations of a compound meandering channel. The traditional power law represents a vertical distribution of longitudinal velocity in open channel with maximum value at free surface and with zero at the channel bed. But the velocity distribution in the type of natural or laboratory compound meandering channel does not follow such velocity distribution. The longitudinal velocity distribution of a compound meandering channel shows two characteristics for all cases and depth ratios. In the bend section, velocity increases in the inner bend (convex) and decreases in the outer bend (concave). Similar nature is observed in the floodplain boundary for all cases and depth ratios. In the crossover of a compound meandering channel, velocity increases towards the mid-section and decreases in the boundary of the channel.

Flow structure around a row of vertical rods in a floodplain

This paper presents the results of an experimental study to determine the effect of a row of vertical cylindrical rods on the structure of turbulent flow inside a symmetrical rectangular compound open channel. The coherent turbulent flow structure or bursting events and associated shear stresses play an important role in sediment entrainment and bed instability in an open channel. Therefore, in this study, three-dimensional bursting analysis is used to find the turbulent flow structure at the edge of a floodplain. The study used a model of a symmetrical rectangular compound channel in which ratio of the main channel width B to the floodplain width b was 1·5. A row of cylindrical wooden rods was installed on the floodplain bed at different distances d from the edge of the floodplain (d/b = 0, 0·1, 0·2, 0·3 and 0·4). Three-dimensional flow velocities were measured using an acoustic Doppler velocity meter (micro-ADV). For different experimental tests, the contribution probability of bursting events to the Reynolds shear stress was computed at different points of the flow depth. Minimum values for the contribution probability of shear stress were found for internal, external sweep and ejection events at the edge of floodplain for d/b equal to 0·1. Furthermore, the transition probability of internal, external sweep and external ejection events for d/b = 0·1 decreased at the intersection of the floodplain and main channel. Although scaling of the experimental results requires further study for application to wide rivers, these findings may be useful in practical applications for narrow rivers.

Hydroacoustic Doppler Technology: A Key Element in the Improvement of Winter Hydrometric Data Quality

Significant progress has been made in the past years to improve the quality of streamflow data and to assess the potential of hydroacoustics. However, little effort has been made in monitoring techniques for under-ice streamflow. This paper presents a case study in which the under-ice index velocity method is used for monitoring ice-affected streamflow with an acoustic Doppler velocity meter (ADVM). The method is particularly interesting since it is reliable during periods of backwater effects, and it is fully automated and objective. In this particular case study, a reliable rating was obtained in five years, with only two discharge measurements per year.