Estimation Of Hydrodynamic Parameters Research Articles

Hydrodynamic Characterization of Carbonate Aquifers Using Atypical Pumping Tests without the Interruption of the Drinking Water Supply

The Gran Sasso carbonate aquifer is the largest and most productive in the Apennines. Its hydrogeological structure has been studied since the middle of the last century for the springs’ characterization for drinking purposes and for a motorway tunnel. Meanwhile, its hydrodynamic parametrization is less developed and has been limited to monitoring the discharge and chemical and isotopic parameters. Secondary porosity characterizes the aquifer, and an underlying impermeable marly complex represents the basal aquiclude. It might appear inappropriate to characterize the hydraulic properties via pumping tests, as their reliability has been proven in homogeneous and isotropic media. However, the high extent of the aquifer, the wells’ location, the scarcity of information available and the lack of alternatives has forced the estimation of hydrodynamic parameters as in porous aquifers and the experimental testing of the aquifer, especially in maximum pumping conditions, for a possible exploitation increase. Since aquifer testing was performed during the normal well field’s activities, it was not possible to perform typical tests. Therefore, the step-drawdown test was conducted by turning on an increasing number of wells over time and keeping the observation points fixed. As results, a mean hydraulic conductivity of 5 × 10−3 m/s and a mean transmissivity of 0.3 m2/s were established without interrupting the water supply; meanwhile, the influence radius and flow directions were also estimated.

Effect of Sampling Rate in Sea Trial Tests on the Estimation of Hydrodynamic Parameters for a Nonlinear Ship Manoeuvring Model

This paper explores the impact of sampling rates during sea trials on the estimation of hydrodynamic parameters in a nonlinear manoeuvring model. Sea trials were carried out using an offshore patrol vessel and test data were collected. A nonlinear manoeuvring model is introduced to characterise the ship’s manoeuvring motion, and the truncated least squares support vector machine is employed to estimate nondimensional hydrodynamic coefficients and their corresponding uncertainties using the 25°–25° zigzag test. To assess the influence of the sampling rates, the training set is resampled offline with 14 sampling rates, ranging from 0.2 Hz to 5 Hz, encompassing a rate 10 times the highest frequency component of the signal of interest. The results show that the higher sampling rate can significantly diminish the parameter uncertainty. To obtain a robust estimation of linear and nonlinear hydrodynamic coefficients, the sampling rate should be higher than 10 times the highest frequency component of the signal of interest, and 3–5 Hz is recommended for the case in this paper. The validation is also carried out, which indicates that the proposed truncated least square support vector machine can provide a robust parameter estimation.

Hydrodynamic Parameters Estimation Using Varying Forces and Numerical Integration Fitting Method

This paper presents a new experimental method for the estimation of hydrodynamic parameters of underwater vehicles, namely the added mass and drag coefficients. The principle is to accurately record the movement of the vehicle in response to a known time-varying actuating force, and find an optimal solution for the parameters that allows simulating a velocity trajectory that fits the recorded trajectory. The optimal solution is obtained using a Numerical Integration Fitting method, which, employing an error minimization algorithm, successively generates velocity trajectories through numerical integration until the parameters converge. This method is applied to determine the hydrodynamic parameters of a torpedo-shaped Autonomous Underwater Vehicle (AUV). The hydrodynamic parameters obtained are compared and found to be close to their theoretical values. In addition, the use of a time-varying force is shown to provide better and more reliable results than the use of a constant or zero external force.

Estimation of the hydrodynamic parameters of USVs for velocity prediction using a hybrid adaptive strategy

PurposeHydrodynamic parameter estimation is significant for the velocity prediction of unmanned surface vehicles. Considering the field data’s uncertain nonlinearities (environmental disturbances and measurement noise), this paper aims to propose a hybrid adaptive parameter estimation (HAPE) strategy.Design/methodology/approachFirst, a rough estimation of hydrodynamic parameters is used by the least squares method. Second, an improved adaptive parameter estimation algorithm is applied to compensate for the influence of uncertain nonlinearities and adjust the parameters within the rough range. Finally, it is proved that the calculated velocity asymptotically converges to the actual value during the parameter estimation procedure.FindingsThe numerical simulation and pool experiments are conducted in two scenarios of steady turning and sinusoidal thrust to verify the effectiveness of the proposed HAPE method. The results validate that the accuracy of the predicted velocity using the hydrodynamic model obtained by the HAPE strategy is better than the APE algorithm. In addition, the hydrodynamic parameters estimated with the sinusoidal thrust data are more applicable than the steady turning data.Originality/valueThis study proposes a HAPE strategy that considers the uncertain nonlinearities of the field data. This method provides a more accurate predicted velocity. Besides, as far as we know, it is the first time to analyze the influence of different test conditions on the accuracy of the predicted velocity.

Assessing the impacts of hydrodynamic parameter uncertainties on simulated evapotranspiration in a mountainous watershed

Accurate quantification of the evolution of water resources requires a better understanding of the movements of water and energy from the subsurface to the lower atmosphere; physically-based integrated hydrologic models provide one of the key approaches to build such understanding. However, these models utilize a significant number of parameters that are measured only sparsely if at all—in particular, the hydrodynamic parameters. In this work, we perform a global sensitivity analysis to quantify the sensitivity of evapotranspiration (ET) to the hydrodynamic parameters. We study the East River watershed located in the Coloradobasinand characterized by cold and snowy winters and hot summers, high topographic gradients, and heterogeneous land cover and geology. Our results highlight that hydrodynamic parameter uncertainties lead to 20% to 50% uncertainties in ET.In areas characterized by a disconnection betweengroundwaterand land surface processes (under water-limited conditions),hydrodynamic parameter uncertainties strongly impactETwhich is highly sensitive to the parameters describing the unsaturated zone parameters. Conversely, in energy-limited areas where plants have year-round access to groundwater,ETis mainly sensitive to the effects of saturated hydraulic conductivities. ET uncertainties due to the uncertainties in hydrodynamic parameters were higher than those associated with the river stages and water table depths. Therefore,ETmeasurements could be used to improve the estimation of hydrodynamic parameters.

Estimation of hydrodynamic parameters for underwater systems using a simple off-line regression method: a case study

Estimation of hydrodynamic model parameters such as added mass parameter and drag coefficients is very crucial while mathematically modelling any underwater system. Owing to the nature of the model being coupled and its high non-linearity, estimation of these parameters becomes complicated. Various methods of parameter estimation have been currently employed, involving experiments, computational fluid analysis, and simulations, each having its own advantages and disadvantages. Most of the existing methods use sophisticated external instrumentation and experimentally estimate the parameters using computationally expensive adaptive algorithms, which may not be required or cannot be generalised to all the systems. In this paper, a simple off-line estimation method for estimating crucial hydrodynamic parameters using onboard sensors is presented. The error between the data from numerical simulations (using a mathematical model) and experiments is iteratively minimised using a gradient descent-based optimisation algorithm, by having the unknown model parameters as design variables of the error minimisation process. The method combines the properties of least squares estimation and the free decay tests, where the system can be excited with any known external inputs. A mathematical model with the unknown parameters, fully defining the behaviour of the system, is required and open loop experimental data from onboard sensors for a known input is sufficient for the estimation process, thereby eliminating the requirement of additional instrumentation. Non-linear mathematical models can be directly used in estimation, unlike few other methods which require linearisation and approximation. This method can be generalised to any system, provided sufficient information on experimental input and output, and the equivalent mathematical model of the system are available. The proposed method has been successfully implemented to estimate the added mass and drag coefficients of a standalone, single degree of freedom variable buoyancy module, ‘vBuoy’. A mathematical model defining the dynamics of the heave motion of vBuoy has been derived and the parameters involved in the model have been estimated with the proposed method. The proposed method, as well as the results, are validated by comparing the experiments and simulations at different conditions. The results showed that the proposed method was well suited for the estimation of hydrodynamic parameters of underwater systems.

Estimation of Hydrodynamic Parameters of Connecting Rod Plain Bearings of Pumping Plant of Powered Mine Support

Expert evaluation of damage the connecting rod bearing shells UNP55-250 pump unit was performed. The finite elements method is used to calculate oil flow in the bearing clearance. Influence of operating defects on the parameters of hydrodynamics is also estimated. Calculations for various designs of connecting rod bearings are carried out and impact of various surface compliances is estimated.

Wave energy farm design in real wave climates: the Italian offshore

The work focuses on hydrodynamic interactions between heaving wave energy converters (WEC). Wave parks of four devices are simulated in the time domain by a hydrodynamic-electromagnetic model, coupled with a boundary element code for the estimation of hydrodynamic parameters. Different layouts (linear, square and rhombus), WEC separation distances (5, 10, 20 and 30 buoy diameters) and incident wave directions (30° apart) are considered to assess the effect of design parameters on array power production. Then, a site-specific design optimization is carried out for different Italian locations and some key insights on wave farm design in real wave climates are provided. The results show that the effect of wave interactions on energy absorption is not expected to be a main issue, as long as the devices are separated by at least 10 buoy diameters and that the layouts are oriented to achieve the maximum energy absorption for the prevailing wave direction.

Modeling of Injection Parameters for Diesel Engine Injector Nozzles with the Additional Precision Guiding Interface

Perfection of output parameters of diesel engines is considered as a result of the rail-pressure increase and modernization of nozzle tribosystems represented at high (up to 300 MPa) values of the fuel pressure. The nozzle with the modified design and additional (bottom) precision guiding interface is used and hydrodynamic parameters of injection are analyzed. The computational fluid-dynamic (CFD) modeling for estimation of hydrodynamic parameters of the fuel flow and force distribution in the “needle – nozzle body” system is used. The results of the injection modeling and contact parameters for the modified design of nozzle precision interfaces are established and discussed. The ways of increasing the stability of needle position in the nozzle body with perfection of parameters of fuel injection are presented.

Effects of sinuosity factor on hydrodynamic parameters estimation in karst systems: a dye tracer experiment from the Beyyayla sinkhole (Eskişehir, Turkey)

The sinuosity factor (SF) is a critical value in karst systems in terms of estimating their hydrodynamic parameters including groundwater velocity, coefficient of dispersion, etc., through dye tracer experiments. SF has been used in a number of different dye tracer experiments in karstic systems to estimate a representative flow path. While knowing SF is crucially important in the estimation of hydrodynamic parameters, its calculation is associated with significant uncertainty due to the complexity of subsurface karstic features. And yet, only a few studies have discussed its uncertainties, which might lead some errors in estimation of hydrodynamic parameters from dye tracer experiment. In this study, dye tracer experiments were conducted in two consecutive years (2003 and 2004) representing low and high flow conditions in the Beyyayla sinkhole (Eskisehir, Turkey) where the flow path is well known. Uranine was used in experiments as a tracer and QTRACER computer program was used to determine the hydrodynamic properties of the Beyyayla karst system as well as to gain insights into the effects of SF from dye tracer experiments on estimated parameters. The results showed that the breakthrough curve follows a unimodal and a bimodal distribution in low and high flow conditions, respectively. These different distributions stem from the water transport mechanisms, where velocities were calculated as 58.2 and 93.6 m h−1 during low and high flow conditions observed in a spring emerging from the south side of the studied system. The results also show that the coefficient of dispersion, Reynolds number, and Peclet number increased and longitudinal dispersivity decreased with the higher flow rate. Furthermore, the estimated parameters did not vary with either the flow conditions or the tracer transit time, but they have shown some variations with SF. When SF was increased by 50 %, a change in these parameters was obtained in the range of 50–125 %.

Depression storage and infiltration effects on overland flow depth-velocity-friction at desert conditions: field plot results and model

Abstract. Water infiltration and overland flow are relevant in considering water partition among plant life forms, the sustainability of vegetation and the design of sustainable hydrological models and management. In arid and semi-arid regions, these processes present characteristic trends imposed by the prevailing physical conditions of the upper soil as evolved under water-limited climate. A set of plot-scale field experiments at the semi-arid Patagonian Monte (Argentina) were performed in order to estimate the effect of depression storage areas and infiltration rates on depths, velocities and friction of overland flows. The micro-relief of undisturbed field plots was characterized at z-scale 1 mm through close-range stereo-photogrammetry and geo-statistical tools. The overland flow areas produced by controlled water inflows were video-recorded and the flow velocities were measured with image processing software. Antecedent and post-inflow moisture were measured, and texture, bulk density and physical properties of the upper soil were estimated based on soil core analyses. Field data were used to calibrate a physically-based, mass balanced, time explicit model of infiltration and overland flows. Modelling results reproduced the time series of observed flow areas, velocities and infiltration depths. Estimates of hydrodynamic parameters of overland flow (Reynolds-Froude numbers) are informed. To our knowledge, the study here presented is novel in combining several aspects that previous studies do not address simultaneously: (1) overland flow and infiltration parameters were obtained in undisturbed field conditions; (2) field measurements of overland flow movement were coupled to a detailed analysis of soil microtopography at 1 mm depth scale; (3) the effect of depression storage areas in infiltration rates and depth-velocity friction of overland flows is addressed. Relevance of the results to other similar desert areas is justified by the accompanying biogeography analysis of similarity of the environment where this study was performed with other desert areas of the world.

Air dynamics near the soil surface and convective emission of aerosol

Asymptotics for the mass concentration of finely dispersed aerosol are obtained on the basis of in situ measurements in a desert in the Caspian region and estimates of hydrodynamic parameters in the viscous thermal boundary layer near the soil surface. In the problem under consideration, the dynamic velocity (friction speed) and the temperature drop in the thermal boundary layer are external parameters. The model of a porous soil layer, in which the air dynamics is described with the use of the Darcy equation, is considered a possible mechanism of aerosol export. The estimates of the critical parameters at which sand particles thermally roll over in soil pores are obtained.

Convective aerosol fluxes near the ground surface

1. The asymptotics for mass concentration of finely dispersed aerosol and estimates of hydrodynamic parameters in the viscous thermal boundary layer near the ground surface were obtained on the basis of field measurements in the Caspian desert. The dynamic velocity and temperature drop in the thermal boundary layer are external parameters of the problem considered. The underlying surface, which can emit particles into the atmosphere under specific conditions, is one of the atmospheric aerosol sources. Experimental data and theoretical estimates show that separation of particles from the surface can be related to turbulent stresses induced by velocity shear in the boundary layer over the underlying surface. It occurs when dynamic velocity u ∗ reaches a critical value of ~20‐30 cm/s (see [1] and references in this publication). The dynamic velocity (friction velocity) u ∗ = 〈 u ' v ' 〉 1/2 proportional to turbulent velocity pulsations determines the thickness δ ∗ of the viscous boundary layer near the underlying (smooth) surface, δ ∗ ~ , ν ≈ 0.13 cm 2 /s is the kinematic viscosity of air. The value of δ ∗ is of the order of 100 µ m for the values of u ∗ given here. Particles with sizes exceeding this value can be separated from the boundary layer depending on the degree of cohesion with the underlying surface and their mass. A different situation is related to small sand and dust particles whose size D is significantly smaller than δ ∗ ( D ~ 0.1– 10 µ m). They are completely located in the viscous boundary layer, where turbulent stresses of the wind velocity decrease sharply and cannot overcome the cohesion force between particles. However, the experiν u * mental data provide evidence that particles with an even sum-micrometer size of the ground origin are found in the atmosphere. Several mechanisms exist that explain the appearance of small submicrometer sand and dust particles in the atmosphere. The most known among them are the saltation mechanism when particles of 100 µ m in size separated from the ground release smaller particles during the impact when they fall onto the surface; another mechanism is related to electrization of particles [2]. The former of these mechanisms is directly related to the influence of sufficiently strong turbulent velocity pulsations on the particles of medium size, which appear only when the mean wind velocity reaches sufficiently high values (~10 m/s) in the upper part of the surface boundary layer. However, the amount of small particles in the atmosphere and conditions of their appearance indicate that their ascent can also occur during period that can be characterized as calm weather and when the wind force is obviously insufficient for the formation of strong shear turbulence over the underlying surface [3].

Observation of a Stormy Wave Field with X-Band Radar and its Linear Aspects

An X-band nautical radar system was employed to observe the wave field during a storm around the research pier HORS in Hasaki, Japan. The radar system provides instantaneous distributions of wave crests in the near-shore region, with image sequences comprising a clear spatial and temporal variation of the wave pattern. The spectra of radar echo signals and water surface elevations from wave gauge records were compared, and a relatively high coherence for a particular bandwidth was observed. A sequence of radar images was filtered at the dominant frequency, which was used to estimate the wavenumber distribution of the refraction field. The Fast Fourier Transform (FFT) and Maximum Entropy Method (MEM) were used to estimate the wavenumbers. The estimated wave angles were then compared with linear refraction analyses. The water depths along the pier were also estimated using the linear dispersion relationship and compared with the surveyed depths. The linear estimates of hydrodynamic parameters during the passage of the storm are presented in this paper to demonstrate the potential of radar measurements in capturing essential characteristics of coastal dynamics.

Application of inverse regression for estimating molecular masses and Stokes radii of globular proteins by gel filtration chromatography

The aim of this paper is to apply inverse regression as a method for treating experimental data obtained from gel filtration chromatography in order to obtain estimates of hydrodynamic parameters of globular proteins with true confidence intervals. The method is illustrated with the determination, using inverse regression, of molecular mass and Stokes radius for four test proteins (aldolase, chymotrypsinogen A, aldehyde oxidase and xanthine oxidase), from experimental data obtained with a Sephacryl S-300 column. A simple personal computer (PC) program written in standard basic, that is useful for this purpose, is included.

Accuracy and precision in the determination of stokes radii and molecular masses of proteins by gel filtration chromatography

The accuracy and precision of the estimates of hydrodynamic parameters of globular proteins obtained by inverse regression from gel filtration chromatographic data are discussed. The usefulness of gel filtration chromatography as the basis for a rapid and reliable method for the determination of the Stokes radius and the molecular mass is considered. The discussion is supported by an analysis of the models already proposed in the literature, and is based on the precision of the estimates.