Juan-Cheng Yang
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Juan-Cheng Yang has a total of 112 co-authors. Here are the top co-authors by number of shared publications:
- Ming-Jiu Ni
University of Chinese Academy of Sciences
27 shared publications Feng-Chen Li
8 shared publicationsMing-Jiu Ni
University of Chinese Academy of Sciences
6 shared publicationsTian-Yu Qi
6 shared publications- Ze Lyu
School of Engineering Science, University of Chinese Academy of Sciences 2 , Beijing 100049
6 shared publications Ze Lyu
University of Chinese Academy of Sciences
5 shared publications
Latest Publications
- 12 October 2026
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1044, A40
Experimental study of the anisotropic decay of homogeneous isotropic magnetohydrodynamic turbulence
We report an experimental study of the free decay of magnetohydrodynamic homogeneous isotropic turbulence at low magnetic Reynolds number and interaction parameter left parenthesis upper N tilde 1 right parenthesis $(N\sim 1)$ . An initially isotropic turbulent state is generated in a cubic vessel by eight converging jets under a uniform magnetic field, and the velocity field is measured using particle image velocimetry. After the jets are switched off, the kinetic energy decays in two successive stages, following a t Superscript negative 1 divided by 2 $t^{-1/2}$ scaling at early times and a t Superscript negative 3 divided by 2 $t^{-3/2}$ scaling at later times. Energy budget analysis shows that these regimes correspond to distinct decay mechanisms: Joule dissipation dominates the early decay, whereas viscous dissipation controls the late-time dynamics. Owing to the anisotropic nature of Joule dissipation, turbulent motions with gradients perpendicular to the magnetic field are preferentially damped, leading to a transient increase in kinetic energy anisotropy, with a maximum ratio of 1.54 at upper N equals 1.28 $N = 1.28$ . This process also causes the two-dimensional energy spectrum to deviate from isotropy and leads to a steepening of the energy spectrum associated with the velocity component perpendicular to the magnetic field. Mode-to-mode energy transfer analysis indicates the coexistence of forward and inverse transfers at perpendicular scales, while only forward transfer persists along the magnetic field. As a consequence, vortical structures progressively elongate in the field direction, with the integral length scale growing as t Superscript 1 divided by 2 $t^{1/2}$ .- 12 October 2026
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1044, A40
Experimental study of the anisotropic decay of homogeneous isotropic magnetohydrodynamic turbulence
We report an experimental study of the free decay of magnetohydrodynamic homogeneous isotropic turbulence at low magnetic Reynolds number and interaction parameter left parenthesis upper N tilde 1 right parenthesis $(N\sim 1)$ . An initially isotropic turbulent state is generated in a cubic vessel by eight converging jets under a uniform magnetic field, and the velocity field is measured using particle image velocimetry. After the jets are switched off, the kinetic energy decays in two successive stages, following a t Superscript negative 1 divided by 2 $t^{-1/2}$ scaling at early times and a t Superscript negative 3 divided by 2 $t^{-3/2}$ scaling at later times. Energy budget analysis shows that these regimes correspond to distinct decay mechanisms: Joule dissipation dominates the early decay, whereas viscous dissipation controls the late-time dynamics. Owing to the anisotropic nature of Joule dissipation, turbulent motions with gradients perpendicular to the magnetic field are preferentially damped, leading to a transient increase in kinetic energy anisotropy, with a maximum ratio of 1.54 at upper N equals 1.28 $N = 1.28$ . This process also causes the two-dimensional energy spectrum to deviate from isotropy and leads to a steepening of the energy spectrum associated with the velocity component perpendicular to the magnetic field. Mode-to-mode energy transfer analysis indicates the coexistence of forward and inverse transfers at perpendicular scales, while only forward transfer persists along the magnetic field. As a consequence, vortical structures progressively elongate in the field direction, with the integral length scale growing as t Superscript 1 divided by 2 $t^{1/2}$ .- 8 September 2026
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1042, A47
Anomalous thermal behaviour of liquid metals in confined Rayleigh–Bénard convection
This study examines anomalous thermal transport in confined liquid metal Rayleigh–Bénard convection via direct numerical simulations over Rayleigh numbers italic Ra element of left bracket 10 Superscript 5 Baseline comma 10 Superscript 8 Baseline right bracket $\textit{Ra} \in [10^5, 10^8]$ . A phenomenological hybrid model is introduced to capture the full transition from the near-wall boundary layer to the non-monotonic core, and the presence of an inverse mean temperature gradient in the bulk is shown to originate from the spatial organization of dynamic thermal blobs. For temperature fluctuations, a spatial characterization of the temperature standard-deviation profile ( sigma Subscript upper T $\sigma _T$ ) reveals a distinctive bimodal structure, with a secondary peak emerging away from the wall. Through variation of spanwise confinement, no-slip sidewalls are found to constrain the development of corner vortices, reorganizing them into a coherent spiral-like precession. This three-dimensional flow topology induces intense spanwise velocity fluctuations, which are associated with the transport and trapping of boundary-layer thermal plumes in the core region, thereby supporting the formation of the anomalous near-core sigma Subscript upper T $\sigma _T$ peak. At the largest Rayleigh numbers considered, the strengthening of turbulent mixing and large-scale circulation weakens this coherent corner-vortex activity, leading to the attenuation of the bimodal signature. Furthermore, we show that such quasi-two-dimensional confinement modifies the macroscopic heat transfer scaling, producing a steeper effective exponent ( italic Nu tilde italic Ra Superscript 0.332 $\textit{Nu} \sim \textit{Ra}^{0.332}$ ) compared with classical predictions – a phenomenon closely tied to the morphological condensation of thermal plumes.- 8 September 2026
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1042, A47
Anomalous thermal behaviour of liquid metals in confined Rayleigh–Bénard convection
This study examines anomalous thermal transport in confined liquid metal Rayleigh–Bénard convection via direct numerical simulations over Rayleigh numbers italic Ra element of left bracket 10 Superscript 5 Baseline comma 10 Superscript 8 Baseline right bracket $\textit{Ra} \in [10^5, 10^8]$ . A phenomenological hybrid model is introduced to capture the full transition from the near-wall boundary layer to the non-monotonic core, and the presence of an inverse mean temperature gradient in the bulk is shown to originate from the spatial organization of dynamic thermal blobs. For temperature fluctuations, a spatial characterization of the temperature standard-deviation profile ( sigma Subscript upper T $\sigma _T$ ) reveals a distinctive bimodal structure, with a secondary peak emerging away from the wall. Through variation of spanwise confinement, no-slip sidewalls are found to constrain the development of corner vortices, reorganizing them into a coherent spiral-like precession. This three-dimensional flow topology induces intense spanwise velocity fluctuations, which are associated with the transport and trapping of boundary-layer thermal plumes in the core region, thereby supporting the formation of the anomalous near-core sigma Subscript upper T $\sigma _T$ peak. At the largest Rayleigh numbers considered, the strengthening of turbulent mixing and large-scale circulation weakens this coherent corner-vortex activity, leading to the attenuation of the bimodal signature. Furthermore, we show that such quasi-two-dimensional confinement modifies the macroscopic heat transfer scaling, producing a steeper effective exponent ( italic Nu tilde italic Ra Superscript 0.332 $\textit{Nu} \sim \textit{Ra}^{0.332}$ ) compared with classical predictions – a phenomenon closely tied to the morphological condensation of thermal plumes.- 1 September 2026
- Published by American Physical Society (APS) in Physical Review Fluids
- Vol. 11 (9) , 094801
Experimental study on the free surface of liquid metal film flow under the influence of gas jet impingement
Compared with a static liquid film, gas jet impingement on a flowing liquid metal film produces a shallower cavity and a strongly asymmetric profile through upstream liquid accumulation. Counter-current coupling upstream and co-current coupling downstream cause the wave-amplitude response to jet momentum to weaken upstream but strengthen downstream as the liquid Reynolds number increases. Under pulsating jets, an attenuation coefficient correlates wave amplitude with jet momentum and characterizes a pronounced spatial asymmetry in momentum transfer. These findings clarify how gas jets influence the liquid metal film flow and provide a reference for the design of liquid metal divertors.
- 1 September 2026
- Published by American Physical Society (APS) in Physical Review Fluids
- Vol. 11 (9) , 094801
Experimental study on the free surface of liquid metal film flow under the influence of gas jet impingement
Compared with a static liquid film, gas jet impingement on a flowing liquid metal film produces a shallower cavity and a strongly asymmetric profile through upstream liquid accumulation. Counter-current coupling upstream and co-current coupling downstream cause the wave-amplitude response to jet momentum to weaken upstream but strengthen downstream as the liquid Reynolds number increases. Under pulsating jets, an attenuation coefficient correlates wave amplitude with jet momentum and characterizes a pronounced spatial asymmetry in momentum transfer. These findings clarify how gas jets influence the liquid metal film flow and provide a reference for the design of liquid metal divertors.
- Open Access
- 27 March 2026
- Published by Elsevier in SSRN Electronic Journal
Design of a flowing liquid lithium target for a linear plasma device
To address the challenges of high heat flux and plasma - material interactions faced by first-wall materials in nuclear fusion reactors, this study presents the design of a flowing liquid lithium experimental device - Plasma - Liquid Lithium Unified Test Platform (PLUTO) - suitable for high-flux plasma environments. The PLUTO system consists of a plasma source, a liquid lithium circulation loop, and a magnet assembly. The loop is driven by argon gas, enabling the uniform distribution (over an effective area ≥100 × 100 mm2) and cyclic recovery of liquid lithium on a target plate. The target assembly is equipped with a horizontal translation capability of 200 mm and an adjustable inclination angle ranging from 45° to 60°. Plasma parameters were characterized using a Langmuir probe, which revealed a maximum beam flux density of 1.4×1024 m−2 s−1 in the central region. Thermodynamic simulations of the target plate were performed with ANSYS Fluent. The results indicate that a finned water-cooling structure provides optimal cooling performance, maintaining a minimum liquid lithium surface temperature of 437°C. Moreover, within the inclination range of 45° to 60°, the peak surface temperature gradually decreases as the angle increases, reaching 425°C at 60°.This study offers essential design insights and experimental data to support the development of liquid – solid divertor concepts.
- 27 March 2026
- Published by Elsevier in SSRN Electronic Journal
Open AccessDesign of a flowing liquid lithium target for a linear plasma device
To address the challenges of high heat flux and plasma - material interactions faced by first-wall materials in nuclear fusion reactors, this study presents the design of a flowing liquid lithium experimental device - Plasma - Liquid Lithium Unified Test Platform (PLUTO) - suitable for high-flux plasma environments. The PLUTO system consists of a plasma source, a liquid lithium circulation loop, and a magnet assembly. The loop is driven by argon gas, enabling the uniform distribution (over an effective area ≥100 × 100 mm2) and cyclic recovery of liquid lithium on a target plate. The target assembly is equipped with a horizontal translation capability of 200 mm and an adjustable inclination angle ranging from 45° to 60°. Plasma parameters were characterized using a Langmuir probe, which revealed a maximum beam flux density of 1.4×1024 m−2 s−1 in the central region. Thermodynamic simulations of the target plate were performed with ANSYS Fluent. The results indicate that a finned water-cooling structure provides optimal cooling performance, maintaining a minimum liquid lithium surface temperature of 437°C. Moreover, within the inclination range of 45° to 60°, the peak surface temperature gradually decreases as the angle increases, reaching 425°C at 60°.This study offers essential design insights and experimental data to support the development of liquid – solid divertor concepts.
- 1 February 2026
- Published by AIP Publishing in Physics of Fluids
- Vol. 38 (2)
Laminar magnetohydrodynamic flow of liquid metal in an annulus under an axial magnetic field driven by direct current
This paper investigates the behavior of electrically driven liquid metal flow in an annular cylindrical domain subjected to a strong axial magnetic field. The flow is induced by a radial electric current passing through liquid metal, generating an azimuthal Lorentz force that drives motion in the θ-direction. Starting with the full set of axisymmetric magnetohydrodynamic (MHD) equations, we derive an analytical solution based on the assumptions of a strong magnetic field and negligible secondary flows. This axisymmetric model captures the dominant electric potential fields and corresponding azimuthal velocity distribution, which enables the convenient prediction of velocity profiles. The analysis focuses on the axisymmetric regime where curvature effects are negligible. To validate the model, we construct an experimental system using electric potential velocimetry for accurate velocity measurements. A consistency in the velocity profiles is observed between the experiment and model predictions, although some deviations appear at higher Reynolds numbers (or lower Hartmann numbers) due to the onset of nonlinearity. The present model serves as a benchmark for MHD systems of annular configurations and provides the exact base flow required for future investigations into flow instabilities and turbulence.
- 1 February 2026
- Published by AIP Publishing in Physics of Fluids
- Vol. 38 (2)
Laminar magnetohydrodynamic flow of liquid metal in an annulus under an axial magnetic field driven by direct current
This paper investigates the behavior of electrically driven liquid metal flow in an annular cylindrical domain subjected to a strong axial magnetic field. The flow is induced by a radial electric current passing through liquid metal, generating an azimuthal Lorentz force that drives motion in the θ-direction. Starting with the full set of axisymmetric magnetohydrodynamic (MHD) equations, we derive an analytical solution based on the assumptions of a strong magnetic field and negligible secondary flows. This axisymmetric model captures the dominant electric potential fields and corresponding azimuthal velocity distribution, which enables the convenient prediction of velocity profiles. The analysis focuses on the axisymmetric regime where curvature effects are negligible. To validate the model, we construct an experimental system using electric potential velocimetry for accurate velocity measurements. A consistency in the velocity profiles is observed between the experiment and model predictions, although some deviations appear at higher Reynolds numbers (or lower Hartmann numbers) due to the onset of nonlinearity. The present model serves as a benchmark for MHD systems of annular configurations and provides the exact base flow required for future investigations into flow instabilities and turbulence.
- 1 December 2025
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 96 (12)
Validation of the electrical potential method for the liquid metal local velocity and temperature measurements under the magnetic field
In the present study, a practical method is proposed and validated for the simultaneous measurement of local flow velocity and temperature in liquid metals under magnetic fields. The method leverages the Seebeck effect to measure temperature and the electromotive force induced by the fluid’s motion in a magnetic field to determine velocity. Theoretical analysis and experimental validation confirm the method’s accuracy, with temperature deviations within 0.15 K and velocity measurements deviating less than 5%. The study introduces a combined potential method for measuring the Seebeck coefficient of liquid metals, which eliminates errors associated with temperature gradient measurements. Experiments demonstrate that the thermomagnetic effect has a negligible impact on potential measurements under the investigated conditions. This key finding validates a direct signal processing pathway, allowing for the precise determination of velocity by simply eliminating the now-quantified thermoelectric effects from the total measured signal. The findings highlight the method’s potential for real-time flow monitoring in high-temperature, opaque fluids, offering significant advancements over traditional measurement techniques.
- 1 December 2025
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 96 (12)
Validation of the electrical potential method for the liquid metal local velocity and temperature measurements under the magnetic field
In the present study, a practical method is proposed and validated for the simultaneous measurement of local flow velocity and temperature in liquid metals under magnetic fields. The method leverages the Seebeck effect to measure temperature and the electromotive force induced by the fluid’s motion in a magnetic field to determine velocity. Theoretical analysis and experimental validation confirm the method’s accuracy, with temperature deviations within 0.15 K and velocity measurements deviating less than 5%. The study introduces a combined potential method for measuring the Seebeck coefficient of liquid metals, which eliminates errors associated with temperature gradient measurements. Experiments demonstrate that the thermomagnetic effect has a negligible impact on potential measurements under the investigated conditions. This key finding validates a direct signal processing pathway, allowing for the precise determination of velocity by simply eliminating the now-quantified thermoelectric effects from the total measured signal. The findings highlight the method’s potential for real-time flow monitoring in high-temperature, opaque fluids, offering significant advancements over traditional measurement techniques.
- Open Access
- 26 November 2025
- Published by ASME International in Applied Mechanics Reviews
- Vol. 78 (1) , 1-105
Magnetohydrodynamics in Liquid Metal Interfacial Flows
Liquid metal interfacial flows occur in the fields of nuclear fusion and electromagnetic metallurgy. Due to the electrically conductive characteristics of the liquid metal, the presence of magnetic fields in these application scenarios has significant impacts on the interfacial flow behaviors. Then typical interfacial flows under the influence of magnetic fields, such as the free surface liquid metal flow, the liquid metal droplet impacting problems, and the bubble motion in liquid metal, are discussed in the present review. We comprehensively illustrate the flow characteristics of free surface liquid metal flow, the spreading of liquid metal droplets impacting onto solid or liquid surfaces, outcomes of collisions between metal droplets, and bubble dynamics in liquid metal, under the influence of magnetic fields along different directions. Meanwhile, we briefly review the current concepts of liquid metal free surface flow plasma facing components (PFCs) in fusion reactors and finally make a summary for the open questions related to the fundamental research and industrial applications of interfacial flow magnetohydrodynamics in the future.
- 26 November 2025
- Published by ASME International in Applied Mechanics Reviews
- Vol. 78 (1) , 1-105
Open AccessMagnetohydrodynamics in Liquid Metal Interfacial Flows
Liquid metal interfacial flows occur in the fields of nuclear fusion and electromagnetic metallurgy. Due to the electrically conductive characteristics of the liquid metal, the presence of magnetic fields in these application scenarios has significant impacts on the interfacial flow behaviors. Then typical interfacial flows under the influence of magnetic fields, such as the free surface liquid metal flow, the liquid metal droplet impacting problems, and the bubble motion in liquid metal, are discussed in the present review. We comprehensively illustrate the flow characteristics of free surface liquid metal flow, the spreading of liquid metal droplets impacting onto solid or liquid surfaces, outcomes of collisions between metal droplets, and bubble dynamics in liquid metal, under the influence of magnetic fields along different directions. Meanwhile, we briefly review the current concepts of liquid metal free surface flow plasma facing components (PFCs) in fusion reactors and finally make a summary for the open questions related to the fundamental research and industrial applications of interfacial flow magnetohydrodynamics in the future.
- Open Access
Magnetic modulation of flow reversals in liquid metal thermal convection
Flow reversals are rarely observed in low-Prandtl-number liquid metal convection due to the fluid's exceptionally high thermal diffusivity. Here, we demonstrate that an external transverse magnetic field can induce such reversals in a quasi-two-dimensional (Q2D) rectangular cell with an aspect ratio ($\itΓ$) of $0.2$. Our experimental observations reveal that the system initially exhibits periodic dynamics at the onset of reversals before transitioning to stochastic behavior as the ratio of Rayleigh number ($Ra$) to Hartmann number ($Ha$) increases. This transition is governed by the competition between buoyancy and Lorentz forces, with experimental data showing a linear scaling relationship between $Ra$ and $Ha$ at critical points. We develop a theoretical model that incorporates magnetic field effects in low-Prandtl-number convection to predict the reversal frequencies. These findings provide new insights into how magnetic fields can modulate flow regimes in low-Prandtl-number convection, establishing a controlled framework for investigating reversal dynamics in magnetohydrodynamic systems.Open AccessMagnetic modulation of flow reversals in liquid metal thermal convection
Flow reversals are rarely observed in low-Prandtl-number liquid metal convection due to the fluid's exceptionally high thermal diffusivity. Here, we demonstrate that an external transverse magnetic field can induce such reversals in a quasi-two-dimensional (Q2D) rectangular cell with an aspect ratio ($\itΓ$) of $0.2$. Our experimental observations reveal that the system initially exhibits periodic dynamics at the onset of reversals before transitioning to stochastic behavior as the ratio of Rayleigh number ($Ra$) to Hartmann number ($Ha$) increases. This transition is governed by the competition between buoyancy and Lorentz forces, with experimental data showing a linear scaling relationship between $Ra$ and $Ha$ at critical points. We develop a theoretical model that incorporates magnetic field effects in low-Prandtl-number convection to predict the reversal frequencies. These findings provide new insights into how magnetic fields can modulate flow regimes in low-Prandtl-number convection, establishing a controlled framework for investigating reversal dynamics in magnetohydrodynamic systems. - 7 October 2025
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1020, A33
Temperature characteristics along the centreline in quasi-two-dimensional Rayleigh–Bénard convection filled with liquid metal
In the present study, we observe interesting profiles and fluctuations in a quasi-two-dimensional thermal convection system filled with low-Prandtl-number liquid metal. A high-precision thermistor, which can be precisely controlled to move up and down, is used to measure the temperature distribution along the centreline of a convection cell. As the thermistor probes move away from the heated wall surface, the measured temperatures initially decrease to values below the central temperature of the cell, then recover to the central temperature, indicating an inverse temperature gradient. Furthermore, by analysing the root-mean-square temperature ( $\sigma _T (z)$ ) along the centreline, we find a second peak away from the wall location, which has never been reported before, in addition to the first peak associated with the thermal boundary thickness. This phenomenon is also confirmed by the results of third- and fourth-order moments of temperature. Experimental results, together with insights from previous studies, suggest that in liquid metal, the distinct flow organisation arising from the large thermal diffusivity plays an important role in shaping the observed temperature distribution.- 7 October 2025
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1020, A33
Temperature characteristics along the centreline in quasi-two-dimensional Rayleigh–Bénard convection filled with liquid metal
In the present study, we observe interesting profiles and fluctuations in a quasi-two-dimensional thermal convection system filled with low-Prandtl-number liquid metal. A high-precision thermistor, which can be precisely controlled to move up and down, is used to measure the temperature distribution along the centreline of a convection cell. As the thermistor probes move away from the heated wall surface, the measured temperatures initially decrease to values below the central temperature of the cell, then recover to the central temperature, indicating an inverse temperature gradient. Furthermore, by analysing the root-mean-square temperature ( $\sigma _T (z)$ ) along the centreline, we find a second peak away from the wall location, which has never been reported before, in addition to the first peak associated with the thermal boundary thickness. This phenomenon is also confirmed by the results of third- and fourth-order moments of temperature. Experimental results, together with insights from previous studies, suggest that in liquid metal, the distinct flow organisation arising from the large thermal diffusivity plays an important role in shaping the observed temperature distribution.- 19 September 2025
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1019, A20
Interfacial wave coupling in an orbitally rotating cylinder
This study explores interfacial waves in a three-layer fluid system, focusing on the coupling effects between the two interfaces. These effects include resonance induced by inertial coupling and damping caused by viscous coupling. A linear theoretical framework is developed to describe the coupled wave motion and evaluate the impact of interfacial coupling under viscous damping. Additionally, a semi-analytical model is introduced to accurately capture resonance frequency shifts and phase differences due to viscosity. The spiral structure of interfacial waves predicted by the models is confirmed experimentally using the background oriented Schlieren (BOS) method. Further, the model is validated by excellent agreement between theoretical predictions and ultrasonic measurements of wave amplitudes and phase differences. Finally, the study examines mechanical coupling and energy transfer between interfaces under external forcing, elucidating the formation of spiral waves. The accurate treatment of viscous boundary conditions by the semi-analytical model also enables its extension to multilayer fluid systems.
- 19 September 2025
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1019, A20
Interfacial wave coupling in an orbitally rotating cylinder
This study explores interfacial waves in a three-layer fluid system, focusing on the coupling effects between the two interfaces. These effects include resonance induced by inertial coupling and damping caused by viscous coupling. A linear theoretical framework is developed to describe the coupled wave motion and evaluate the impact of interfacial coupling under viscous damping. Additionally, a semi-analytical model is introduced to accurately capture resonance frequency shifts and phase differences due to viscosity. The spiral structure of interfacial waves predicted by the models is confirmed experimentally using the background oriented Schlieren (BOS) method. Further, the model is validated by excellent agreement between theoretical predictions and ultrasonic measurements of wave amplitudes and phase differences. Finally, the study examines mechanical coupling and energy transfer between interfaces under external forcing, elucidating the formation of spiral waves. The accurate treatment of viscous boundary conditions by the semi-analytical model also enables its extension to multilayer fluid systems.