Effect Of Water Flow Velocity Research Articles

The Effect of Water Flow Velocity on Heat Collection Performance of Active Heat Storage and Release System for Solar Greenhouses

In order to explore the influence of water velocity on the heat collection performance of the active heat storage and release system for solar greenhouses in Table l and, six different flow rates were selected for treatment in this experiment. The comprehensive heat transfer coefficient of the active heat storage and release system at the heat collection stage was calculated by measuring the indoor solar radiation intensity, indoor air temperature and measured water tank temperature. The prediction model of water temperature in the heat collection stage was established, and the initial value of water temperature and the comprehensive heat transfer coefficient were input through MATLAB software. The simulated value of water temperature was compared with the measured value and the results showed that the best heat transfer effect could be achieved when the water flow speed was 1.0 m3h-1. The average relative error between the simulated water tank temperature and the measured value is 2.70–6.91%. The results indicate that the model is established correctly, and the variation trend of water temperature can be predicted according to the model in the heat collection stage.

Gone with the flow: Whitefish egg drift in relation to substrate coarseness under a range of flow velocities.

Most major rivers in Europe have been dammed for hydropower or other purposes. Such river alterations have decimated natural reproduction of many migratory fish species, including that of the anadromous European whitefish, Coregonus lavaretus, which is now maintained by extensive stocking programmes. In addition to stocking, limited natural reproduction may occur downstream of dams, where peak flow bouts from the dams threaten to flush the eggs into unsuitable habitats. Here, we assessed the effects of water flow velocity and substrate coarseness on downstream drift of whitefish eggs under laboratory conditions. The experiment's two different gravel substrates retained eggs better than cobble or sand substrates; the water velocity needed for notable egg drift was higher for the gravel substrates. The results indicate that egg drift is one of the factors that should be considered when evaluating the effects of hydropower plant operations. Moreover, measures mitigating the effects of the artificial flow regimes should incorporate the type and coarseness of the riverbed's substrate.

The Effects of Water Flow Speed on Swimming Capacity and Energy Metabolism in Adult Amur Grayling (Thymallus grubii)

The present study aimed to explore whether water flow velocity could affect the swimming ability and overall energy metabolism of wild Amur grayling (Thymallus grubii). Swimming performance was assessed by measuring critical swimming speed (Ucrit), burst speed (Uburst), and oxygen consumption rate (MO2) based on the stepped velocity test method. Our results showed that the absolute values of Ucrit and Uburst tended to increase with body length. In contrast, the relative values of Ucrit and Uburst tended to decrease and increase, respectively. MO2 in Amur grayling was elevated with increasing velocity, suggesting relatively high swimming efficiency. We also measured the biochemical indices related to energy metabolism. Lactate dehydrogenase, hexokinase, and pyruvate kinase activities significantly increased (p < 0.05). Hepatic glycogen, glucose, and muscle glycogen contents decreased with the increasing trend of velocity (p < 0.05), the lactic acid contents of the blood and muscles increased significantly with the increase in velocities (p < 0.05), and changes in creatine phosphate content showed no significant difference (p > 0.05). The results not only denote the relationship between body size and swimming speed but also show the effects of water flow velocity on energy metabolism in Amur grayling. The results provide basic data for the construction of fish passage.

The trade-off effects of water flow velocity on denitrification rates in open channel waterways

Ditches and river networks play crucial roles in nitrogen (N) removal within aquatic ecosystems, and their effectiveness depends on various biogeochemical and hydraulic factors. Among these, water flow velocity, as a hydraulic factor, has been relatively underexplored due to the limited N removal quantifying method in flowing open channel waterway. In this study, we used argon as a tracer to calibrate the diffusion coefficient of N2. We then applied the gas diffusion coefficient method to assess how water flow velocity affects denitrification rates. Our results provide new insights into the trade-off role of water flow velocity in N removal through denitrification across a range of flow velocities (0, 1, 4, 6, 10 cm s−1) in open channel waterway. This trade-off effect arises from the interplay between increased NO3− transfer and rising dissolved oxygen levels as water flow velocity increases, resulting in an initially increased and subsequently declined denitrification rate with increased water flow velocities. The denitrification rates reached maximum and minimum values at the water flow velocity of 4 cm s−1 and 0 cm s−1, respectively, regardless of the presence of vegetation. Average denitrification rates ranged from 36.8 to 358.8 µmol N2 m−2h−1 in unvegetated sediments and from 133.0 to 383.5 µmol N2 m−2h−1 in vegetated sediments within the spectrum of water flow velocities. In addition, we observed significantly higher denitrification rates at night than during the day, likely due to the photosynthesis and respiration processes associated with plant metabolism. These findings of this study contribute to the understanding of how water flow velocity affects denitrification rates and provide valuable information for the simulation and restoration efforts aimed at enhancing the N removal capacity of river networks.

Experimental analysis and model prediction of elbow pipe's erosion in water-cooled radiator

The radiator with heat transfer capability is able to guarantee the stable operation of hydro generator set, while the long-term and continuous scouring on radiator pipes by cooling medium will lead to thinning or even perforation of pipe wall, which triggers wall failure. This paper analyzes and predicts the failure mechanism of radiator’s pipe wall, and investigates the effects of water flow velocity, sand content and sand particle size on erosion damage of radiator pipe by establishing a test bench for pipe erosion. The results show that the increase of above parameters will lead to the increasing erosion rate, especially when the sand content is 1%, the velocity is 8 m/s and the sand particle size is 0.85 mm, the erosion damage will be particularly serious. Based on experimental data, BP and LSSVM models are employed to predict the pipe wall failure, and PSO algorithm is used to optimize the two models. The optimized PSO-BP has the highest accuracy with the mean absolute error (MAE) of 0.2070 and the mean absolute percentage error (MAPE) of 4.702%. The findings provide a reference for wall failure analysis of radiator, which is of great significance for unit's safe operation.

A novel numerical method for grouting simulation in flowing water considering uneven spatial and temporal distribution of slurry: Two-Fluid Tracking (TFT) method

To address the issue of uneven spatial and temporal distribution of slurry viscosity in the grouting process, we propose a novel numerical method for grouting in flowing water based on the Euler-Euler framework: two-fluid tracking (TFT) method. The proposed method is capable of capturing the entire grouting process. First, we develop a time transport model that can calculate the transport time of the slurry at any location. Subsequently, the numerical verification proves that the simulated results of transport time can reflect the residence time of the slurry. We then combine the transport time and time-varying viscosity equation to reveal the spatial-temporal evolution of slurry viscosity. Furthermore, the effectiveness and accuracy of the numerical method in different injected media are verified by comparing against laboratory tests, analytical solutions, and simulation results in the literature. In addition, the diffusion behavior of the slurry under different water flow velocities is analyzed, and the effects of water flow velocity and grout flow rate on grouting pressure are discussed. This study can provide useful guidance and reference for slurry selection and parameter optimization in grouting engineering practices.

Deposition of corrosion products under pressurised water nuclear reactor conditions: The effect of flow velocity and dissolved hydrogen

The effect of water flow velocity and dissolved hydrogen on the deposition rate of Corrosion-Related Unidentified Deposit (CRUD) was investigated under conditions relevant to pressurised water nuclear reactors using type 304 l stainless steel micro-orifices. The results indicate that the CRUD build-up rate increases with hydrogen concentration because the amount of iron in solution also increases. At the same time, the fluid shear forces induce a mechanical removal of the oxide for flow velocities above 15 m/s. This suggests that the CRUD deposition process occurs under mass transport control, but the overall build-up rate is also affected by flow-induced mechanical removal.

Effect of water flow velocity on the growth of the kelp Saccharina japonica under unilateral flow

Effect of water flow velocity on the growth of the kelp <i>Saccharina japonica</i> under unilateral flow

Experimental study of direct contact vaporization heat transfer on n-pentane-water flowing interface

The direct contact vaporization heat transfer is studied on a small circular interface which is a direct contact interface between the n-pentane injected in a tubule and the immiscible hot water flowing in the channel at the high velocity turbulent state. The interface water temperature is measured by infrared thermograph to obtain the actual driving temperature difference. The effects of water flow velocity and temperature on heat transfer coefficient have been investigated experimentally. In addition, the vapor bubbles characteristics on interface are investigated by visualization research. The results show that the actual driving temperature difference of 8.92 °C is far lower than the traditional temperature difference of 37.9 °C, which causes that their heat transfer coefficients have more than 4 times deviation. The heat transfer coefficient increases as the water flow velocity increases, but decreases with the increase of the driving temperature difference. The n-pentane vaporization rate increases gradually with an increase of water flow velocity and the actual driving temperature difference. The bubbles diameters increase as the water temperature increases, which causes that it is easier to form gas film to reduce the heat transfer coefficient.

A new approach to plane failure of rock slope stability based on water flow velocity in discontinuities for the Latian dam reservoir landslide

The stability of slopes is always of great concern in the field of rock engineering. The geometry and orientation of pre-existing discontinuities show a larger impact on the behavior of slopes that is often used to describe the measurement of the steepness, incline, gradient, or grade of a straight line. One of the structurally controlled modes of failure in jointed rock slopes is plane failure. There are numerous analytical methods for the rock slope stability including limit equilibrium, stress analysis and stereographic methods. The limiting equilibrium methods for slopes under various conditions against plane failure have been previously proposed by several investigators. However, these methods do not involve water pressure on sliding surfaces assessments due to water velocity and have not yet been validated by case study results. This paper has tried to explore the effects of forces due to water pressure on discontinuity surfaces in plane failure through applying the improved equations. It has studied the effect of water flow velocity on sliding surfaces in safety factor, as well. New equations for considering water velocity (fluid dynamics) are presented. To check the validity of the suggested equations, safety factor for a case study has been determined. Results show that velocity of water flow had significant effect on the amount of safety factor. Also, the suggested equations have higher validity rate compared to the current equations.

Effect of water flow velocity on growth and morphology of cultured Undaria pinnatifida sporophytes (Laminariales, Phaeophyceae) in Okirai Bay on the Sanriku coast, Northeast Japan

Undaria pinnatifida sporophytes, originating from the same strain, were cultured at the commercial cultivation site exposed to wave action and the uncultivated site protected from water action of Okirai Bay, Northeast Japan, from January to April 2007; simultaneously, water flow velocity, water temperature, salinity, NO3 + NO2, and chlorophyll a were monitored to investigate the effect of water environment on their growth and morphology. Water temperature and salinity fluctuated within the optimal range for their growth whereas water flow velocity at the cultivation site was greatly fast compared with that at the uncultivated site. Successive chlorophyll a increases synchronized with NO3 + NO2 decreases were observed only at the uncultivated site for over a month; indicating developments of phytoplankton blooms and their nutrient consumption under the low-flow condition. Meanwhile, blade growth rate of cultured sporophytes was higher at the cultivation site than at the uncultivated site. Their thallus size expressed by six morphological characters (blade length, stipe length, blade wet weight, stipe wet weight, blade width, and undivided blade width) at the cultivation site became large in comparison with that at the uncultivated site. Their three morphological correlations (correlations between blade length and thallus length; blade wet weight and thallus wet weight; and undivided blade width and blade width) differed between the sites. They produced a thick and flat blade at the cultivation site but formed a thin and wrinkled blade at the uncultivated site. These results show the significant impact of water flow velocity on their growth and morphology.

Dynamical analysis of carbon nanotubes conveying water considering carbon–water bond potential energy and nonlocal effects

In this research, free vibration analysis of Single Walled Carbon Nanotubes (SWCNTs) conveying water is studied. The effects of water flow velocity, CNT’s chirality, diameter and aspect ratio, elastic foundation stiffness, nonlocal parameter magnitude, and end condition on the system’s natural frequencies are studied. In this work, water is considered as a discrete medium. Using the carbon–water bond potential energy for modeling the interaction between carbon atoms and water molecules is the main difference between the present work and the previous ones done by others.New interesting results are achieved which indicate that continuum assumption for water media leads to new results. The results show that the fundamental frequency decreases by increasing the water flow velocity and by decreasing the stiffness of the elastic foundation. It also decreases by increasing nanotube aspect ratio as the beam theories predict. But, it decreases as the nonlocal parameter magnitude increases. Furthermore, the fundamental frequency is smaller for SWCNTs with larger diameter.

Effects of water flow velocity and fish culture on net biofouling in fish cages

The effects of water flow, fish feed and cage position on net biofouling was examined in a floating cage fish farm. Fouling of 16 mm mesh net panels suspended inside and outside net cages and exposed to different treatments were monitored weekly until net apertures were completely occluded by the fouling organisms (8 weeks). Results indicate a dramatic reduction in water flow velocity throughout the fish farm due to the cage units themselves and net biofouling. The reduced water flow (<10 cm s−1) inside net cages promoted rapid net biofouling, while rapid water flow outside the net cages (>25 cm s−1) kept the net fouling organisms at bay. Although fish rearing in net cages with inputs of commercial pellet feed increased sessile biofouling (222% higher than outside the net cages) and non-sessile biofouling (570% higher), the type of fish feed used did not significantly affect biofouling development. The study recommends that the geometry of serially arranged net cages, as commonly deployed in tropical tidal estuaries, be reconfigured to improve flow through in order to minimize the impact of fouling.

水中溶接における冷却過程の評価

Underwater welding technologies are of growing importance with increasing of waterfront projects. Underwater welding technique also provides effective means for repairing many kinds of offshore structures. It should be pointed out, however, that such important properties as the cooling cycle and the joint strength in the underwater welding are not fully understood. In the previous studies, cooling cycle of underwater welding conducted in the water at rest was investigated. From a site welding point of view, it is necessary to elucidate how a tidal current and a wave affect the welding operations and the strength of welded joint.In this paper, underwater welding is performed in the running water, and the effects of water flow velocity on the cooling process are studied. The experiments are conducted in a water tank especially designed for this purpose, where the flow velocity is varied up to 30cm/sec. Accordingly, significant characteristics of the cooling curves and cooling rates are estimated.