The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
S Balachandar - One of the best experts on this subject based on the ideXlab platform.
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influence of baroclinic vorticity production on unsteady drag coefficient in shock Particle Interaction
Journal of Applied Physics, 2019Co-Authors: K Fujisawa, T L Jackson, S BalachandarAbstract:The influence of baroclinic vorticity production on the unsteady drag coefficient in shock–Particle Interaction is numerically studied. Numerical simulations are performed for shock–Particle Interaction utilizing a high–resolution axisymmetric solver for the Euler equations that allows for multi-material interface and shock propagation in both the Particle and surrounding medium. We consider an aluminum Particle in nitromethane and allow for Particle deformation. We compute the vorticity production and unsteady drag coefficient as a function of time to explain the complex physical mechanisms that occur during shock–Particle Interaction. We observe baroclinic vorticity production as the shock propagates over the Particle and find that the vorticity is primarily generated at the surface of the Particle. After the passage of the shock over the Particle, the generated vortex traverses downstream, thus creating a sharpened Particle edge and low pressure on the downstream side of the Particle, followed by the trapping of the vortex at the Particle edge. These mechanisms lead to the generation of a quasi-steady drag force even after the passage of the shock, thus suggesting the importance of baroclinic vorticity production to the unsteady drag coefficient. Finally, we compute the unsteady drag coefficient for various shock Mach numbers and Particle ellipticities.The influence of baroclinic vorticity production on the unsteady drag coefficient in shock–Particle Interaction is numerically studied. Numerical simulations are performed for shock–Particle Interaction utilizing a high–resolution axisymmetric solver for the Euler equations that allows for multi-material interface and shock propagation in both the Particle and surrounding medium. We consider an aluminum Particle in nitromethane and allow for Particle deformation. We compute the vorticity production and unsteady drag coefficient as a function of time to explain the complex physical mechanisms that occur during shock–Particle Interaction. We observe baroclinic vorticity production as the shock propagates over the Particle and find that the vorticity is primarily generated at the surface of the Particle. After the passage of the shock over the Particle, the generated vortex traverses downstream, thus creating a sharpened Particle edge and low pressure on the downstream side of the Particle, followed by the t...
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importance of unsteady contributions to force and heating for Particles in compressible flows part 1 modeling and analysis for shock Particle Interaction
International Journal of Multiphase Flow, 2011Co-Authors: Yue Ling, A Haselbacher, S BalachandarAbstract:Abstract Shock–Particle Interaction is an important phenomenon. The Interaction can be accurately resolved by direct numerical simulations. However, as the length scales of interest are much larger than the Particle size in many applications, fully resolving the flow around the Particle is impractical. Therefore, rigorous model for momentum and energy exchange in the Interaction is very important. Shock–Particle Interaction is strongly time-dependent, so unsteady mechanisms play important roles in momentum and energy transfer. A model that includes unsteady contributions to force and heating is proposed. The model is used to investigate Particle Interactions with a planar shock wave and a spherical shock wave. The peak values and the net effects of unsteady contributions are used to measure their importance. The results show the peak values of unsteady contributions are much larger than the quasi-steady ones for a wide range of Particle parameters. The net effects of unsteady contributions are important when the Particle-to-gas density ratio is small. For the flow behind the spherical shock is unsteady and non-uniform, unsteady contributions have long-time influence on the Particle evolution.
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modeling of the unsteady force for shock Particle Interaction
Shock Waves, 2009Co-Authors: M Parmar, A Haselbacher, S BalachandarAbstract:The Interaction between a Particle and a shock wave leads to unsteady forces that can be an order of magnitude larger than the quasi-steady force in the flow field behind the shock wave. Simple models for the unsteady force have so far not been proposed because of the complicated flow field during the Interaction. Here, a simple model is presented based on the work of Parmar et al. (Phil Trans R Soc A 366:2161–2175, 2008). Comparisons with experimental and computational data for both stationary spheres and spheres set in motion by shock waves show good agreement in terms of the magnitude of the peak and the duration of the unsteady force.
Yoshizumi Miyoshi - One of the best experts on this subject based on the ideXlab platform.
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Diffuse and Pulsating Aurora
Space Science Reviews, 2020Co-Authors: Yukitoshi Nishimura, Yoshizumi Miyoshi, Yuto Katoh, Keisuke Hosokawa, Marc R. Lessard, Eric Grono, Noora Partamies, Nithin Sivadas, Mizuki Fukizawa, Marilia SamaraAbstract:This chapter reviews fundamental properties and recent advances of diffuse and pulsating aurora. Diffuse and pulsating aurora often occurs on closed field lines and involves energetic electron precipitation by wave-Particle Interaction. After summarizing the definition, large-scale morphology, types of pulsation, and driving processes, we review observation techniques, occurrence, duration, altitude, evolution, small-scale structures, fast modulation, relation to high-energy precipitation, the role of ECH waves, reflected and secondary electrons, ionosphere dynamics, and simulation of wave-Particle Interaction. Finally we discuss open questions of diffuse and pulsating aurora.
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Visualization of rapid electron precipitation via chorus element wave–Particle Interactions
Nature Publishing Group, 2019Co-Authors: Mitsunori Ozaki, Yoshiya Kasahara, Yoshizumi Miyoshi, Kazuo Shiokawa, Keisuke Hosokawa, Shin-ichiro Oyama, Ryuho Kataoka, Yusuke Ebihara, Yasunobu Ogawa, Satoshi YagitaniAbstract:Electron precipitation plays major role in magnetospheric physics and space weather. Here the authors show nonlinear behavior of the wave–Particle Interaction in the magnetosphere as the evolution of chorus electromagnetic waves detected by the Arase satellite and PWING observatory
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Data processing in Software-type Wave-Particle Interaction Analyzer onboard the Arase satellite
Earth Planets and Space, 2018Co-Authors: M. Hikishima, Hirotsugu Kojima, Nana Higashio, Satoshi Kasahara, Yoshiya Kasahara, Yoshizumi Miyoshi, Yuto Katoh, Ayako Matsuoka, T. Mitani, Kazushi AsamuraAbstract:The software-type wave–Particle Interaction analyzer (S-WPIA) is an instrument package onboard the Arase satellite, which studies the magnetosphere. The S-WPIA represents a new method for directly observing wave–Particle Interactions onboard a spacecraft in a space plasma environment. The main objective of the S-WPIA is to quantitatively detect wave–Particle Interactions associated with whistler-mode chorus emissions and electrons over a wide energy range (from several keV to several MeV). The quantity of energy exchanges between waves and Particles can be represented as the inner product of the wave electric-field vector and the Particle velocity vector. The S-WPIA requires accurate measurement of the phase difference between wave and Particle gyration. The leading edge of the S-WPIA system allows us to collect comprehensive information, including the detection time, energy, and incoming direction of individual Particles and instantaneous-wave electric and magnetic fields, at a high sampling rate. All the collected Particle and waveform data are stored in the onboard large-volume data storage. The S-WPIA executes calculations asynchronously using the collected electric and magnetic wave data, data acquired from multiple Particle instruments, and ambient magnetic-field data. The S-WPIA has the role of handling large amounts of raw data that are dedicated to calculations of the S-WPIA. Then, the results are transferred to the ground station. This paper describes the design of the S-WPIA and its calculations in detail, as implemented onboard Arase.
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software type wave Particle Interaction analyzer on board the arase satellite
Earth Planets and Space, 2018Co-Authors: Yuto Katoh, Hirotsugu Kojima, M. Hikishima, Satoshi Kasahara, Yoshiya Kasahara, Yoshizumi Miyoshi, Kazushi Asamura, Takeshi Takashima, Takefumi Mitani, Nana HigashioAbstract:We describe the principles of the Wave–Particle Interaction Analyzer (WPIA) and the implementation of the Software-type WPIA (S-WPIA) on the Arase satellite. The WPIA is a new type of instrument for the direct and quantitative measurement of wave–Particle Interactions. The S-WPIA is installed on the Arase satellite as a software function running on the mission data processor. The S-WPIA on board the Arase satellite uses an electromagnetic field waveform that is measured by the waveform capture receiver of the plasma wave experiment (PWE), and the velocity vectors of electrons detected by the medium-energy Particle experiment–electron analyzer (MEP-e), the high-energy electron experiment (HEP), and the extremely high-energy electron experiment (XEP). The prime objective of the S-WPIA is to measure the energy exchange between whistler-mode chorus emissions and energetic electrons in the inner magnetosphere. It is essential for the S-WPIA to synchronize instruments to a relative time accuracy better than the time period of the plasma wave oscillations. Since the typical frequency of chorus emissions in the inner magnetosphere is a few kHz, a relative time accuracy of better than 10 μs is required in order to measure the relative phase angle between the wave and velocity vectors. In the Arase satellite, a dedicated system has been developed to realize the time resolution required for inter-instrument communication. Here, both the time index distributed over all instruments through the satellite system and an S-WPIA clock signal are used, that are distributed from the PWE to the MEP-e, HEP, and XEP through a direct line, for the synchronization of instruments within a relative time accuracy of a few μs. We also estimate the number of Particles required to obtain statistically significant results with the S-WPIA and the expected accumulation time by referring to the specifications of the MEP-e and assuming a count rate for each detector.
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Significance of Wave-Particle Interaction Analyzer for direct measurements of nonlinear wave-Particle Interactions
Annales Geophysicae, 2013Co-Authors: Yuto Katoh, M. Kitahara, Hirotsugu Kojima, Satoshi Kasahara, Yoshiharu Omura, Yoshizumi Miyoshi, Kanako Seki, Kazushi Asamura, Masafumi Hirahara, Takeshi TakashimaAbstract:Abstract. In the upcoming JAXA/ERG satellite mission, Wave Particle Interaction Analyzer (WPIA) will be installed as an onboard software function. We study the statistical significance of the WPIA for measurement of the energy transfer process between energetic electrons and whistler-mode chorus emissions in the Earth's inner magnetosphere. The WPIA measures a relative phase angle between the wave vector E and velocity vector v of each electron and computes their inner product W, where W is the time variation of the kinetic energy of energetic electrons interacting with plasma waves. We evaluate the feasibility by applying the WPIA analysis to the simulation results of whistler-mode chorus generation. We compute W using both a wave electric field vector observed at a fixed point in the simulation system and a velocity vector of each energetic electron passing through this point. By summing up Wi of an individual Particle i to give Wint, we obtain significant values of Wint as expected from the evolution of chorus emissions in the simulation result. We can discuss the efficiency of the energy exchange through wave-Particle Interactions by selecting the range of the kinetic energy and pitch angle of the electrons used in the computation of Wint. The statistical significance of the obtained Wint is evaluated by calculating the standard deviation σW of Wint. In the results of the analysis, positive or negative Wint is obtained at the different regions of velocity phase space, while at the specific regions the obtained Wint values are significantly greater than σW, indicating efficient wave-Particle Interactions. The present study demonstrates the feasibility of using the WPIA, which will be on board the upcoming ERG satellite, for direct measurement of wave-Particle Interactions.
Yuto Katoh - One of the best experts on this subject based on the ideXlab platform.
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Diffuse and Pulsating Aurora
Space Science Reviews, 2020Co-Authors: Yukitoshi Nishimura, Yoshizumi Miyoshi, Yuto Katoh, Keisuke Hosokawa, Marc R. Lessard, Eric Grono, Noora Partamies, Nithin Sivadas, Mizuki Fukizawa, Marilia SamaraAbstract:This chapter reviews fundamental properties and recent advances of diffuse and pulsating aurora. Diffuse and pulsating aurora often occurs on closed field lines and involves energetic electron precipitation by wave-Particle Interaction. After summarizing the definition, large-scale morphology, types of pulsation, and driving processes, we review observation techniques, occurrence, duration, altitude, evolution, small-scale structures, fast modulation, relation to high-energy precipitation, the role of ECH waves, reflected and secondary electrons, ionosphere dynamics, and simulation of wave-Particle Interaction. Finally we discuss open questions of diffuse and pulsating aurora.
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Data processing in Software-type Wave-Particle Interaction Analyzer onboard the Arase satellite
Earth Planets and Space, 2018Co-Authors: M. Hikishima, Hirotsugu Kojima, Nana Higashio, Satoshi Kasahara, Yoshiya Kasahara, Yoshizumi Miyoshi, Yuto Katoh, Ayako Matsuoka, T. Mitani, Kazushi AsamuraAbstract:The software-type wave–Particle Interaction analyzer (S-WPIA) is an instrument package onboard the Arase satellite, which studies the magnetosphere. The S-WPIA represents a new method for directly observing wave–Particle Interactions onboard a spacecraft in a space plasma environment. The main objective of the S-WPIA is to quantitatively detect wave–Particle Interactions associated with whistler-mode chorus emissions and electrons over a wide energy range (from several keV to several MeV). The quantity of energy exchanges between waves and Particles can be represented as the inner product of the wave electric-field vector and the Particle velocity vector. The S-WPIA requires accurate measurement of the phase difference between wave and Particle gyration. The leading edge of the S-WPIA system allows us to collect comprehensive information, including the detection time, energy, and incoming direction of individual Particles and instantaneous-wave electric and magnetic fields, at a high sampling rate. All the collected Particle and waveform data are stored in the onboard large-volume data storage. The S-WPIA executes calculations asynchronously using the collected electric and magnetic wave data, data acquired from multiple Particle instruments, and ambient magnetic-field data. The S-WPIA has the role of handling large amounts of raw data that are dedicated to calculations of the S-WPIA. Then, the results are transferred to the ground station. This paper describes the design of the S-WPIA and its calculations in detail, as implemented onboard Arase.
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software type wave Particle Interaction analyzer on board the arase satellite
Earth Planets and Space, 2018Co-Authors: Yuto Katoh, Hirotsugu Kojima, M. Hikishima, Satoshi Kasahara, Yoshiya Kasahara, Yoshizumi Miyoshi, Kazushi Asamura, Takeshi Takashima, Takefumi Mitani, Nana HigashioAbstract:We describe the principles of the Wave–Particle Interaction Analyzer (WPIA) and the implementation of the Software-type WPIA (S-WPIA) on the Arase satellite. The WPIA is a new type of instrument for the direct and quantitative measurement of wave–Particle Interactions. The S-WPIA is installed on the Arase satellite as a software function running on the mission data processor. The S-WPIA on board the Arase satellite uses an electromagnetic field waveform that is measured by the waveform capture receiver of the plasma wave experiment (PWE), and the velocity vectors of electrons detected by the medium-energy Particle experiment–electron analyzer (MEP-e), the high-energy electron experiment (HEP), and the extremely high-energy electron experiment (XEP). The prime objective of the S-WPIA is to measure the energy exchange between whistler-mode chorus emissions and energetic electrons in the inner magnetosphere. It is essential for the S-WPIA to synchronize instruments to a relative time accuracy better than the time period of the plasma wave oscillations. Since the typical frequency of chorus emissions in the inner magnetosphere is a few kHz, a relative time accuracy of better than 10 μs is required in order to measure the relative phase angle between the wave and velocity vectors. In the Arase satellite, a dedicated system has been developed to realize the time resolution required for inter-instrument communication. Here, both the time index distributed over all instruments through the satellite system and an S-WPIA clock signal are used, that are distributed from the PWE to the MEP-e, HEP, and XEP through a direct line, for the synchronization of instruments within a relative time accuracy of a few μs. We also estimate the number of Particles required to obtain statistically significant results with the S-WPIA and the expected accumulation time by referring to the specifications of the MEP-e and assuming a count rate for each detector.
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Significance of Wave-Particle Interaction Analyzer for direct measurements of nonlinear wave-Particle Interactions
Annales Geophysicae, 2013Co-Authors: Yuto Katoh, M. Kitahara, Hirotsugu Kojima, Satoshi Kasahara, Yoshiharu Omura, Yoshizumi Miyoshi, Kanako Seki, Kazushi Asamura, Masafumi Hirahara, Takeshi TakashimaAbstract:Abstract. In the upcoming JAXA/ERG satellite mission, Wave Particle Interaction Analyzer (WPIA) will be installed as an onboard software function. We study the statistical significance of the WPIA for measurement of the energy transfer process between energetic electrons and whistler-mode chorus emissions in the Earth's inner magnetosphere. The WPIA measures a relative phase angle between the wave vector E and velocity vector v of each electron and computes their inner product W, where W is the time variation of the kinetic energy of energetic electrons interacting with plasma waves. We evaluate the feasibility by applying the WPIA analysis to the simulation results of whistler-mode chorus generation. We compute W using both a wave electric field vector observed at a fixed point in the simulation system and a velocity vector of each energetic electron passing through this point. By summing up Wi of an individual Particle i to give Wint, we obtain significant values of Wint as expected from the evolution of chorus emissions in the simulation result. We can discuss the efficiency of the energy exchange through wave-Particle Interactions by selecting the range of the kinetic energy and pitch angle of the electrons used in the computation of Wint. The statistical significance of the obtained Wint is evaluated by calculating the standard deviation σW of Wint. In the results of the analysis, positive or negative Wint is obtained at the different regions of velocity phase space, while at the specific regions the obtained Wint values are significantly greater than σW, indicating efficient wave-Particle Interactions. The present study demonstrates the feasibility of using the WPIA, which will be on board the upcoming ERG satellite, for direct measurement of wave-Particle Interactions.
Kazushi Asamura - One of the best experts on this subject based on the ideXlab platform.
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Data processing in Software-type Wave-Particle Interaction Analyzer onboard the Arase satellite
Earth Planets and Space, 2018Co-Authors: M. Hikishima, Hirotsugu Kojima, Nana Higashio, Satoshi Kasahara, Yoshiya Kasahara, Yoshizumi Miyoshi, Yuto Katoh, Ayako Matsuoka, T. Mitani, Kazushi AsamuraAbstract:The software-type wave–Particle Interaction analyzer (S-WPIA) is an instrument package onboard the Arase satellite, which studies the magnetosphere. The S-WPIA represents a new method for directly observing wave–Particle Interactions onboard a spacecraft in a space plasma environment. The main objective of the S-WPIA is to quantitatively detect wave–Particle Interactions associated with whistler-mode chorus emissions and electrons over a wide energy range (from several keV to several MeV). The quantity of energy exchanges between waves and Particles can be represented as the inner product of the wave electric-field vector and the Particle velocity vector. The S-WPIA requires accurate measurement of the phase difference between wave and Particle gyration. The leading edge of the S-WPIA system allows us to collect comprehensive information, including the detection time, energy, and incoming direction of individual Particles and instantaneous-wave electric and magnetic fields, at a high sampling rate. All the collected Particle and waveform data are stored in the onboard large-volume data storage. The S-WPIA executes calculations asynchronously using the collected electric and magnetic wave data, data acquired from multiple Particle instruments, and ambient magnetic-field data. The S-WPIA has the role of handling large amounts of raw data that are dedicated to calculations of the S-WPIA. Then, the results are transferred to the ground station. This paper describes the design of the S-WPIA and its calculations in detail, as implemented onboard Arase.
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software type wave Particle Interaction analyzer on board the arase satellite
Earth Planets and Space, 2018Co-Authors: Yuto Katoh, Hirotsugu Kojima, M. Hikishima, Satoshi Kasahara, Yoshiya Kasahara, Yoshizumi Miyoshi, Kazushi Asamura, Takeshi Takashima, Takefumi Mitani, Nana HigashioAbstract:We describe the principles of the Wave–Particle Interaction Analyzer (WPIA) and the implementation of the Software-type WPIA (S-WPIA) on the Arase satellite. The WPIA is a new type of instrument for the direct and quantitative measurement of wave–Particle Interactions. The S-WPIA is installed on the Arase satellite as a software function running on the mission data processor. The S-WPIA on board the Arase satellite uses an electromagnetic field waveform that is measured by the waveform capture receiver of the plasma wave experiment (PWE), and the velocity vectors of electrons detected by the medium-energy Particle experiment–electron analyzer (MEP-e), the high-energy electron experiment (HEP), and the extremely high-energy electron experiment (XEP). The prime objective of the S-WPIA is to measure the energy exchange between whistler-mode chorus emissions and energetic electrons in the inner magnetosphere. It is essential for the S-WPIA to synchronize instruments to a relative time accuracy better than the time period of the plasma wave oscillations. Since the typical frequency of chorus emissions in the inner magnetosphere is a few kHz, a relative time accuracy of better than 10 μs is required in order to measure the relative phase angle between the wave and velocity vectors. In the Arase satellite, a dedicated system has been developed to realize the time resolution required for inter-instrument communication. Here, both the time index distributed over all instruments through the satellite system and an S-WPIA clock signal are used, that are distributed from the PWE to the MEP-e, HEP, and XEP through a direct line, for the synchronization of instruments within a relative time accuracy of a few μs. We also estimate the number of Particles required to obtain statistically significant results with the S-WPIA and the expected accumulation time by referring to the specifications of the MEP-e and assuming a count rate for each detector.
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Significance of Wave-Particle Interaction Analyzer for direct measurements of nonlinear wave-Particle Interactions
Annales Geophysicae, 2013Co-Authors: Yuto Katoh, M. Kitahara, Hirotsugu Kojima, Satoshi Kasahara, Yoshiharu Omura, Yoshizumi Miyoshi, Kanako Seki, Kazushi Asamura, Masafumi Hirahara, Takeshi TakashimaAbstract:Abstract. In the upcoming JAXA/ERG satellite mission, Wave Particle Interaction Analyzer (WPIA) will be installed as an onboard software function. We study the statistical significance of the WPIA for measurement of the energy transfer process between energetic electrons and whistler-mode chorus emissions in the Earth's inner magnetosphere. The WPIA measures a relative phase angle between the wave vector E and velocity vector v of each electron and computes their inner product W, where W is the time variation of the kinetic energy of energetic electrons interacting with plasma waves. We evaluate the feasibility by applying the WPIA analysis to the simulation results of whistler-mode chorus generation. We compute W using both a wave electric field vector observed at a fixed point in the simulation system and a velocity vector of each energetic electron passing through this point. By summing up Wi of an individual Particle i to give Wint, we obtain significant values of Wint as expected from the evolution of chorus emissions in the simulation result. We can discuss the efficiency of the energy exchange through wave-Particle Interactions by selecting the range of the kinetic energy and pitch angle of the electrons used in the computation of Wint. The statistical significance of the obtained Wint is evaluated by calculating the standard deviation σW of Wint. In the results of the analysis, positive or negative Wint is obtained at the different regions of velocity phase space, while at the specific regions the obtained Wint values are significantly greater than σW, indicating efficient wave-Particle Interactions. The present study demonstrates the feasibility of using the WPIA, which will be on board the upcoming ERG satellite, for direct measurement of wave-Particle Interactions.
Hang Li - One of the best experts on this subject based on the ideXlab platform.
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coupling effects of surface charges adsorbed counterions and Particle size distribution on soil water infiltration and transport
European Journal of Soil Science, 2018Co-Authors: Y. Gong, Rui Tian, Hang LiAbstract:Soil pores are the channels for water transport. The surface charges, the non‐classic polarizabilities and concentrations of the adsorbed counterions in a soil determine soil Particle Interaction forces that affect soil pore status. Particle‐size distribution is another important factor that affects soil pore status. Therefore, surface charges, adsorbed counterions and Particle‐size distribution would probably be coupled in soil water transport. In this study, two soils with different surface charge densities, different adsorbed counterions and different Particle‐size distributions were used to study their coupling effects on soil water movement. The results showed that these factors were strongly coupled in soil water movement. When the soil electric field strength was strong (depending on surface charges, adsorbed counterion polarizabilities and concentrations), the net Interaction forces of soil Particles was repulsive, thus soil aggregates could be broken. The degree of aggregate breakdown coupled with Particle‐size distribution determined soil water movement. For this case we found that (i) increasing attractive forces of soil Particles could greatly improve soil water movement and (ii) water movement was slow when the soil had large clay or small silt or sand contents. When the soil electric field was weak, the net Interaction force of soil Particles was attractive, thus aggregates could not be broken. For this case we found that (i) further increasing the attractive forces of soil Particles could not improve soil water movement and (ii) water movement was fast when the soil had large clay or small silt or sand contents. HIGHLIGHTS: Coupling effects of Particle size and Particle Interactions on soil water movement are not clear. Large clay contents can decrease or increase soil water movement depending on soil Particle Interaction forces. Fast water movement occurred in soil with strongly polarized cations and large clay content. Particle Interaction forces and Particle‐size distribution were strongly coupled in soil water movement.
