scholarly journals Comparison between sprinkler irrigation and natural rainfall based on droplet diameter

2016 ◽  
Vol 14 (1) ◽  
pp. e1201 ◽  
Author(s):  
MaoSheng Ge ◽  
Pute Wu ◽  
Delan Zhu ◽  
Daniel P. Ames
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Droplet Diameter ◽  
Vertical Component ◽  
Radial Distance ◽  
Sprinkler Irrigation ◽  
Application Rate ◽  
Horizontal Component ◽  
Natural Rainfall ◽  
Actual Field

<p>An indoor experiment was conducted to analyze the movement characteristics of different sized droplets and their influence on water application rate distribution and kinetic energy distribution. Radial droplets emitted from a Nelson D3000 sprinkler nozzle under 66.3, 84.8, and 103.3 kPa were measured in terms of droplet velocity, landing angle, and droplet kinetic energy and results were compared to natural rainfall characteristics. Results indicate that sprinkler irrigation droplet landing velocity for all sizes of droplets is not related to nozzle pressure and the values of landing velocity are very close to that of natural rainfall. The velocity horizontal component increases with radial distance while the velocity vertical component decreases with radial distance. Additionally, landing angle of all droplet sizes decreases with radial distance. The kinetic energy is decomposed into vertical component and horizontal component due to the oblique angles of droplet impact on the surface soil, and this may aggravate soil erosion. Therefore the actual oblique angle of impact should be considered in actual field conditions and measures should be taken for remediation of soil erosion if necessary.</p>

scholarly journals Set-up and calibration of a portable small scale rainfall simulator for assessing soil erosion processes at interrill scale

2017 ◽  
Vol 43 (1) ◽  
pp. 63 ◽  
Author(s):  
J. J. Zemke
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Rainfall Intensity ◽  
Small Scale ◽  
Rainfall Erosivity ◽  
Fall Velocity ◽  
Rainfall Simulator ◽  
Spatial Homogeneity ◽  
Erosion Processes ◽  
Natural Rainfall

A portable rainfall simulator was built for assessing runoff and soil erosion processes at interrill scale. Within this study, requirements and constraints of the rainfall simulator are identified and discussed. The focus lies on the calibration of the simulator with regard to spatial rainfall homogeneity, rainfall intensity, drop size, drop fall velocity and rainfall kinetic energy. These parameters were obtained using different methods including a Laser Precipitation Monitor. A detailed presentation of the operational characteristics is given. The presented rainfall simulator setup featured a rainfall intensity of 45.4 mm·h-1 with a spatial homogeneity of 80.4% based on a plot area of 0.64 m². Because of the comparatively low drop height (2 m), the diameter-dependent terminal fall velocity (1.87 m·s-1) was lower than benchmark values for natural rainfall. This conditioned also a reduced rainfall kinetic energy (4.6 J·m-2·mm-1) compared to natural rainfall with same intensity. These shortfalls, a common phenomenon concerning portable rainfall simulators, represented the best possible trade-off between all relevant rainfall parameters obtained with the given simulator setup. Field experiments proved that the rainfall erosivity was constant and replicable.

scholarly journals TECHNICAL NOTE: The representation of rainfall drop-size distribution and kinetic energy

2004 ◽  
Vol 8 (5) ◽  
pp. 1001-1007 ◽  
Author(s):  
N. I. Fox
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Size Distribution ◽  
Energy Flux ◽  
Drop Size ◽  
Technical Note ◽  
Drop Size Distribution ◽  
Horizontal Component ◽  
Gamma Distributions ◽  
Definition Of

Abstract. To relate observed rainfall rates (R) to the kinetic energy flux (E) that affects soil erosion it is necessary to develop relationships between the two. This paper explores theoretical E–R relationships based on gamma distributions of drop size. The relationship is poorly defined unless assumptions are made about changes in the shape of the drop-size distribution (DSD) with rainfall rate. The study suggests that the assumption of an exponential DSD leads to overestimation of kinetic energy flux. Further, incorporation of a horizontal component of kinetic energy allows for a clearer relationship between kinetic energy and rainfall intensity to be defined, but a question remains regarding the most appropriate definition of the horizontal component of drop velocity. Keywords: drop-size distribution, drop kinetic energy, soil erosion

Analysis of Droplet Characteristics and Kinetic Energy Distribution for Fixed Spray Plate Sprinkler at Low Working Pressure

2021 ◽  
Vol 64 (2) ◽  
pp. 447-460
Author(s):  
Rui Chen ◽  
Hong Li ◽  
Jian Wang ◽  
Xin Guo
Keyword(s):  
Kinetic Energy ◽  
Energy Distribution ◽  
Water Depth ◽  
Droplet Diameter ◽  
Sprinkler Irrigation ◽  
Infiltration Rate ◽  
Kinetic Energy Distribution ◽  
Specific Power ◽  
List Type ◽  
Working Pressure

HighlightsAn experiment was conducted to investigate the hydraulic performance of a fixed spray plate sprinkler (FSPS).A model was developed for estimating the cumulative kinetic energy of the FSPS under a moving system.The droplet characteristics and kinetic energy distribution were affected by the working pressure and FSPS structure.A high cumulative kinetic energy could lead to a low water infiltration rate into the soil.Abstract. The kinetic energy of droplets from a fixed spray plate sprinkler (FSPS) has a substantial influence on runoff and soil erosion, as well as on the energy consumption of moving sprinkler irrigation systems. To determine the droplet characteristics and kinetic energy of an FSPS, an experiment was conducted to investigate the effects of working pressure, plate structure, and nozzle size on the droplet diameter, velocity, and kinetic energy. Two plates (the FSPSB with a concave trajectory and deep grooves in the blue plate, and the FSPSY with a flat trajectory and shallow grooves in the yellow plate) were used in the tests. The cumulative kinetic energy and water depth were calculated for a single sprinkler moving in a straight line. The results show that the FSPSB, which had deeper grooves in the plate, produced a larger droplet diameter than the FSPSY, with shallow grooves in the plate. The droplet landing velocities presented a logarithmic relationship with the droplet diameter, and velocities increased with an increase in droplet diameter. The peak specific power (SP) value of the FSPSB was 1.14 to 16.76 times that of the FSPSY. When the working pressure was less than 150 kPa, the peak SP of the FSPSB remained at a high level. With an increase in working pressure, the peak SP of the FSPSB initially increased and then decreased, while the peak SP of the FSPSY increased. The cumulative kinetic energy of the FSPSB was higher than that of the FSPSY under mobile spray conditions. Compared with the cumulative water depth, the cumulative kinetic energy of the FSPSB increased and then decreased as the working pressure increased for the same applied water volume. Because the soil had a lower infiltration rate under the FSPSB, surface ponding was more likely to occur with the FSPSB than with the FSPSY at low working pressure. Keywords: Cumulative kinetic energy, Droplet size, Specific power, Sprinkler irrigation, Working condition.

scholarly journals Rainfall Parameters Affecting Splash Erosion under Natural Conditions

2020 ◽  
Vol 10 (12) ◽  
pp. 4103 ◽  
Author(s):  
Nives Zambon ◽  
Lisbeth Lolk Johannsen ◽  
Peter Strauss ◽  
Tomas Dostal ◽  
David Zumr ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Linear Function ◽  
Rain Gauge ◽  
Total Kinetic Energy ◽  
Rainfall Erosivity ◽  
Erosion Process ◽  
Good Tool ◽  
Splash Erosion ◽  
Natural Rainfall

The interaction between rainfall erosivity parameters and splash erosion is crucial for describing the soil erosion process; however, it is rarely investigated under natural rainfall conditions. In this study, we conducted splash erosion experiments under natural rainfall on three sites in Central Europe. The main goal was to obtain the relationship between splash erosion of the bare soil in seedbed condition and commonly used rainfall erosivity parameters (kinetic energy, intensity, and rainfall erosivity (EI30)). All sites were equipped with a rain gauge and an optical laser disdrometer where the splash erosion was measured, with modified Morgan splash cups. In order to investigate which parameter best describes the splash erosion process for all sites, a regression analysis was performed. In total, 80 splash erosion events were evaluated. Splash erosion can be described as a linear function of total kinetic energy and a non-linear function of EI30. However, the use of the total kinetic energy led to underestimation of the splash erosion rates for highly intensive rainfalls. Therefore, better results were obtained when using average rainfall intensity as the splash erosion predictor or the kinetic energy divided by the rainfall duration. Minor differences between the replicates during splash erosion measurements indicate that the modified Morgan splash cup provides a good tool for soil erosion assessment.

scholarly journals Effects of Pressure and Nozzle Size on the Spray Characteristics of Low-Pressure Rotating Sprinklers

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2904
Author(s):  
Rui Chen ◽  
Hong Li ◽  
Jian Wang ◽  
Xin Guo
Keyword(s):  
Kinetic Energy ◽  
Droplet Diameter ◽  
Low Pressure ◽  
Application Rate ◽  
Droplet Velocity ◽  
Specific Power ◽  
Working Pressure ◽  
Nozzle Size ◽  
The Mean ◽  
Droplet Trajectory

Using low-pressure sprinklers in agricultural irrigation has become an alternative way of reducing water and energy stress. To determine the applicability of the low-pressure rotating sprinkler, an experiment was conducted to evaluate the effects of working pressure and nozzle size on sprinkler rotation speed, application rate, droplet size, droplet velocity, droplet trajectory angle, and kinetic energy distribution. The results showed that the mean droplet diameter increased exponentially along with the increase in distance from the sprinkler, and a logarithmic relation was derived between droplet diameter and droplet velocity. Due to the low breakup degree of the jet under the lowest working pressure of 100 kPa, the peak values of specific power and application rate were high, which reached 0.09 W m−2 and 11.35 mm h−1, and were 3.1–5.4 times and 2.5–3.1 times those of other working conditions. Meanwhile, the peak specific power of the biggest nozzle (diameter = 5.2 mm) was 2.4–2.8 times that of smaller nozzles. With an increase in working pressure, the sprinkler time per rotation decreased and the distributions of kinetic energy and water became more uniform. Thus, it is not recommended to equip the sprinkler with a large nozzle under low working pressure.

Galilean Relativity

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Inertial Frame ◽  
Vertical Component ◽  
Horizontal Component ◽  
The Other ◽  
One Dimension ◽  
Everyday Experience ◽  
Low Speed ◽  
Principle Of Relativity ◽  
Galilean Relativity ◽  
Laws Of Motion

Galilean relativity is a useful description of nature at low speed. Galileo found that the vertical component of a projectile’s velocity evolves independently of its horizontal component. In a frame that moves horizontally along with the projectile, for example, the projectile appears to go straight up and down exactly as if it had been launched vertically. The laws of motion in one dimension are independent of any motion in the other dimensions. This leads to the idea that the laws of motion (and all other laws of physics) are equally valid in any inertial frame: the principle of relativity. This principle implies that no inertial frame can be considered “really stationary” or “really moving.” There is no absolute standard of velocity (contrast this with acceleration where Newton’s first law provides an absolute standard). We discuss some apparent counterexamples in everyday experience, and show how everyday experience can be misleading.

Peripheral representation of antennal orientation by the scapal hair plate of the cockroach Periplaneta americana

2001 ◽  
Vol 204 (24) ◽  
pp. 4301-4309 ◽  
Author(s):  
J. Okada ◽  
Y. Toh
Keyword(s):  
Single Unit ◽  
Periplaneta Americana ◽  
Vertical Component ◽  
Horizontal Component ◽  
Vertical Position ◽  
Horizontal Position ◽  
Joint Movement ◽  
Basal Segment ◽  
Dynamic Phase ◽  
Hair Sensilla

SUMMARY Arthropods have hair plates that are clusters of mechanosensitive hairs, usually positioned close to joints, which function as proprioceptors for joint movement. We investigated how angular movements of the antenna of the cockroach (Periplaneta americana) are coded by antennal hair plates. A particular hair plate on the basal segment of the antenna, the scapal hair plate, can be divided into three subgroups: dorsal, lateral and medial. The dorsal group is adapted to encode the vertical component of antennal direction, while the lateral and medial groups are specialized for encoding the horizontal component. Of the three subgroups of hair sensilla, those of the lateral scapal hair plate may provide the most reliable information about the horizontal position of the antenna, irrespective of its vertical position. Extracellular recordings from representative sensilla of each scapal hair plate subgroup revealed the form of the single-unit impulses in response to hair deflection. The mechanoreceptors were characterized as typically phasic-tonic. The tonic discharge was sustained indefinitely (&gt;20 min) as long as the hair was kept deflected. The spike frequency in the transient (dynamic) phase was both velocity- and displacement-dependent, while that in the sustained (steady) phase was displacement-dependent.

Consistent Theoretical Model of Mean Diameter and Size Distribution by Liquid Sheet Atomization

2012 ◽  
Author(s):  
Chihiro Inoue ◽  
Toshinori Watanabe ◽  
Takehiro Himeno ◽  
Seiji Uzawa ◽  
Mitsuo Koshi
Keyword(s):  
Theoretical Model ◽  
Kinetic Energy ◽  
Droplet Diameter ◽  
Velocity Profiles ◽  
Liquid Sheet ◽  
Estimation Methods ◽  
Liquid Jets ◽  
Injection Velocity ◽  
Size Distributions ◽  
Mean Diameter

A consistent theoretical model is proposed and validated for calculating droplet diameters and size distributions. The model is derived based on the energy conservation law including the surface free energy and the Laplace pressure. Under several hypotheses, the law derives an equation indicating that atomization results from kinetic energy loss. Thus, once the amount of loss is determined, the droplet diameter is able to be calculated without the use of experimental parameters. When the effects of ambient gas are negligible, injection velocity profiles of liquid jets are the essential cause of the reduction of kinetic energy. The minimum Sauter mean diameter produced by liquid sheet atomization is inversely proportional to the injection Weber number when the injection velocity profiles are laminar or turbulent. A non-dimensional distribution function is also derived from the mean diameter model and Nukiyama-Tanasawa’s function. The new estimation methods are favorably validated by comparing with corresponding mean diameters and the size distributions, which are experimentally measured under atmospheric pressure.

scholarly journals Estimation of rainfall erosivity based on WRF-derived raindrop size distributions

2020 ◽  
Vol 24 (11) ◽  
pp. 5407-5422
Author(s):  
Qiang Dai ◽  
Jingxuan Zhu ◽  
Shuliang Zhang ◽  
Shaonan Zhu ◽  
Dawei Han ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Water Conservation ◽  
Large Scale ◽  
Weather Prediction ◽  
Wrf Model ◽  
Analysis Data ◽  
Rainfall Erosivity ◽  
Size Distributions ◽  
Raindrop Size

Abstract. Soil erosion can cause various ecological problems, such as land degradation, soil fertility loss, and river siltation. Rainfall is the primary water-driven force for soil erosion, and its potential effect on soil erosion is reflected by rainfall erosivity that relates to the raindrop kinetic energy. As it is difficult to observe large-scale dynamic characteristics of raindrops, all the current rainfall erosivity models use the function based on rainfall amount to represent the raindrops' kinetic energy. With the development of global atmospheric re-analysis data, numerical weather prediction techniques become a promising way to estimate rainfall kinetic energy directly at regional and global scales with high spatial and temporal resolutions. This study proposed a novel method for large-scale and long-term rainfall erosivity investigations based on the Weather Research and Forecasting (WRF) model, avoiding errors caused by inappropriate rainfall–energy relationships and large-scale interpolation. We adopted three microphysical parameterizations schemes (Morrison, WDM6, and Thompson aerosol-aware) to obtain raindrop size distributions, rainfall kinetic energy, and rainfall erosivity, with validation by two disdrometers and 304 rain gauges around the United Kingdom. Among the three WRF schemes, Thompson aerosol-aware had the best performance compared with the disdrometers at a monthly scale. The results revealed that high rainfall erosivity occurred in the west coast area at the whole country scale during 2013–2017. The proposed methodology makes a significant contribution to improving large-scale soil erosion estimation and for better understanding microphysical rainfall–soil interactions to support the rational formulation of soil and water conservation planning.

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