Article
Mechanics
Joseph I. Ibrahim, Garazi Gomez-de-Segura, Daniel Chung, Ricardo Garcia-Mayoral
Summary: The virtual origin shift between the mean flow and turbulence is a key parameter for near-wall turbulence. The use of slip-like boundary conditions affects the virtual origins for mean flow and turbulence, determined by the streamwise and wall-normal/spanwise slip lengths. The virtual origin perceived by quasi-streamwise vortices plays a key role in determining the virtual origin for turbulence.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Yulu Liu, Zhihong Ding, Yizhou Tao, Junwang Qu, Xilin Xie, Xiang Qiu
Summary: This study investigates the compressible flow around a circular cylinder near a wall using direct numerical simulation. The results show that compressibility enhances flow stability but reduces the strength, shedding frequency, and fluctuation of shedding vortices with increasing Mach number. The wall inhibits vortices shedding from both the free-stream side and the wall side, with the wall-side vortices being weaker. This imbalance is intensified as the cylinder approaches the wall, leading to a decrease in shedding frequency. Based on the effect of wall proximity on frequency, the flow behavior is divided into three regimes: high-frequency, low-frequency, and completely suppression regimes. The trend of mean drag and lift force coefficients with Mach number and gap ratio is described as a scaling behavior with two piecewise functions.
Article
Mechanics
Fuqi Li, Chuangxin He, Peng Wang, Yingzheng Liu
Summary: The present study numerically modeled turbulent wall heat transfer behind a wall-proximity square rib using dynamic delayed detached-eddy simulations to clarify unsteady flow behaviors and their influence on wall heat transfer. The interaction between different flow structures was found to significantly affect wall heat transfer, demonstrating distinctive characteristics with varying wall gap configurations.
Article
Mechanics
Alexander J. Smits, Marcus Hultmark, Myoungkyu Lee, Sergio Pirozzoli, Xiaohua Wu
Summary: The new scaling shows a Reynolds-number-independent profile for all components of the Reynolds stress in the near-wall region of wall-bounded flows, highlighting the significance of wall shear stress fluctuations and the role of large eddies in determining the Reynolds number dependence of near-wall turbulence behavior.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Qing Wang, Feng Qu, Di Sun, Junqiang Bai
Summary: In this study, the supersonic jet over a convex wall is examined using numerical simulation. The investigation focuses on instabilities, turbulent statistics, and the influence of compressibility effects. The results show that streamwise vortices play a significant role in shear layer instabilities, and compressibility effects inhibit their formation.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Xiaojing Zheng, Guohua Wang, Wei Zhu
Summary: This study investigates the influence of the interaction between heavy particles (high Stokes number) and the wall on two-phase flows and large-scale turbulent structures. Experimental results confirm that the P-W process significantly affects the size and strength of VLSM.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Multidisciplinary
Fathimunnisa, Neetu Srivastava
Summary: This study discusses the acoustic streaming generated by a standing wave over a flat plate in the presence of a magnetic field, dividing the flow into boundary layer and core flow regions. Using the successive approximation method, the velocity expression for the core region is found, confirming that the velocity is independent of viscosity but dependent on a magnetic field, used to demonstrate Couette flow.
AIN SHAMS ENGINEERING JOURNAL
(2021)
Article
Mechanics
Alexander J. Smits
Summary: Our understanding of turbulent boundary layer scaling and structure has greatly advanced in the past few decades, thanks to the progress in numerical simulations and experimental methods.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
L. Chan, T. Zahtila, A. Ooi, J. Philip
Summary: This study investigated the migration and deposition mechanisms of particles in turbulent flow over rough walls with varying roughness parameters and Stokes numbers. The results showed that particles with different Stokes numbers exhibit different behaviors in response to rough wall interactions and turbulent flow dynamics.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
G. G. Rooney
Summary: Dynamical constraints on the wall layer in turbulent pipe flow result in a narrow peak in the streamwise component of the turbulent Lamb vector near the wall, and a scaling relationship between the wall layer depth and the depth of the viscous sublayer. An approximation of the Lamb vector distribution, which is equivalent to the gradient of Reynolds stress, is proposed. Integration of the equation for streamwise mean flow allows for an expression of the velocity profile in the wall layer.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Shang-Gui Cai, Pierre Sagaut
Summary: Algebraic explicit wall models are proposed to cover the entire inner region of the turbulent boundary layer, reducing the computational effort for large eddy simulation of wall-bounded turbulent flows. The models use closed-form formulas with logarithmic- or power-function-based laws of the wall to straightforwardly evaluate the friction velocity on near wall grids, demonstrating good performance in wall modeled large eddy simulation of turbulent plane channel flow.
Article
Mechanics
Akanksha Baranwal, Diego A. Donzis, Rodney D. W. Bowersox
Summary: This study investigates the effects of compressibility on the near-wall asymptotic behavior of turbulent fluxes using a large direct numerical simulation (DNS) database, finding that the behavior of compressible turbulent flow near walls differs from incompressible flow even when mean density variations are considered. As Mach number increases, turbulent fluxes containing wall-normal components exhibit a decrease in slope due to increased dilatation effects, with Ity approaching its high Mach number asymptote at lower Mach numbers than other fluxes.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Sandipan Kumar Das
Summary: This study proposes a new method within the BIM framework to handle symmetry, zero normal-velocity gradient and specified pressure boundary conditions. The method is successfully applied to simple Stokes flow problems and shows good agreement with analytical solutions and literature data.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2023)
Article
Mechanics
Ping Wang, Qingqing Wei, Xiaojing Zheng
Summary: This study used wall-resolved large-eddy simulation and Lagrangian point-force model to simulate particle-laden flow over a rigid wall. It found that high-inertia particles can alter fluid velocity and turbulence structures, reduce near-wall turbulence scales, while splashing of particles on the bed causes changes in turbulence structures.
Article
Mechanics
Xi Chen, Katepalli R. Sreenivasan
Summary: In this article, a self-consistent Reynolds number asymptotics is presented to describe the variations of velocity fluctuation variances and root-mean-square pressure with respect to the wall-normal position in channel flows, pipe flows, and flat-plate boundary layers. The study shows that when normalized by peak values, the Reynolds number dependence and wall-normal variation of these profiles can be decoupled and are in good agreement with experimental and simulation data. Additionally, it is predicted that a finite plateau appears in the outer region for asymptotically high Reynolds numbers.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Chemistry, Applied
Harriet Kildahl, Zhongbo Li, Hui Cao, Peter Slater, Yulong Ding
Summary: A new type of perovskite material BCNF1 has been studied, showing good stability and high mass changes in reduction and re-oxidation cycles, making it suitable for energy storage and conversion systems.
Article
Engineering, Environmental
Chao Song, Xianglei Liu, Hangbin Zheng, Chuang Bao, Liang Teng, Yun Da, Feng Jiang, Chuan Li, Yongliang Li, Yimin Xuan, Yulong Ding
Summary: This study successfully enhanced solar absorptance, cycle stability, and decreased decomposition temperature simultaneously by doping CaCO3 particles, paving the way for the design of high-performance calcium-based materials for next-generation high temperature thermal energy storage systems.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Energy & Fuels
Xuemin Zhao, Yunmin Tang, Binglong Zhao, Changning Wu, Junguo Li, Changqing Chu, Ke Liu, Yulong Ding
Summary: The new collector HIP emulsion significantly reduces oil consumption and shows higher flocculation and flotation efficiency compared to kerosene. High-shear pulping promotes the overall flotation rate of HIP emulsion, but may also lead to degradation of its flocculation ability. HIP emulsions are proven to be a potential economic and efficient collector for ultrafine and high-ash content coal slimes beneficiation.
INTERNATIONAL JOURNAL OF COAL PREPARATION AND UTILIZATION
(2022)
Article
Engineering, Chemical
Tongtong Zhang, Xiaohui She, Yulong Ding
Summary: LNG regasification and liquid air energy storage (LAES) processes waste a significant amount of energy, which can be recovered to improve efficiency, although this would require additional capital investment and may not always be economically attractive.
CHINESE JOURNAL OF CHEMICAL ENGINEERING
(2021)
Article
Thermodynamics
Argyrios Anagnostopoulos, Alessio Alexiadis, Yulong Ding
Summary: A novel set of Lennard-Jones parameters for amorphous silica is proposed in this study, capable of accurately simulating the structure. The existence of a compressed liquid layer at the liquid-nanoparticle interface is observed experimentally, with higher density and lower self-diffusivity of the molten salt mixture in proximity to the interface. Ordered distribution of Na+ and K+ ions is indicated at the interface, suggesting the presence of an ordered double-layer.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Chemistry, Multidisciplinary
Qicheng Chen, Xupan Yang, Yingjin Zhang, Yulong Ding
Summary: The study examined the influence of vacancy defects on the wettability of molten alkali metal salt on the CaO surface using molecular dynamics simulations. The results indicated that higher temperatures and defect concentrations led to poorer wettability of Na2SO4. This was attributed to induced polarization caused by the defect surfaces, ultimately affecting thermal energy transportability at the interface.
Article
Materials Science, Ceramics
Renwei Li, Qicheng Chen, Liang Ouyang, Yingjin Zhang, Binjian Nie, Yulong Ding
Summary: Corrosion prevention is a crucial concern in thermal energy storage, particularly in high-temperature environments. Studying the doped alloy elements revealed that Ti and Mg significantly enhance interfacial bonding strength, while Cr and Ni are ineffective in this aspect. The presence of Mg and Ti atoms at the interface shows an enhancement effect as interfacial binders.
CERAMICS INTERNATIONAL
(2021)
Article
Engineering, Chemical
Mengyao Shen, Lige Tong, Hongsheng Ding, Li Wang, Yulong Ding
Summary: The study demonstrates that as the particle size ratio and the mass fraction of coarse particles increase, the separation degree of binary particles also increases. Additionally, the thickness of the coarse particle layer increases with the increase of the mass fraction of coarse particles.
Article
Energy & Fuels
Qi Miao, Yelong Zhang, Xu Jia, Zhongbo Li, Linghua Tan, Yulong Ding
Summary: Sorption based thermochemical energy storage using salt hydrates offers advantages such as low heat loss, small volume change, and high energy density, but faces challenges of mechanical structure stability and slow charging kinetics. The novel MgSO4-EG composite material shows superior heat and mass transfer properties, with 60% MgSO4 content displaying the best performance.
Article
Energy & Fuels
Yelong Zhang, Qi Miao, Xu Jia, Yi Jin, Zhongbo Li, Linghua Tan, Yulong Ding
Summary: A novel composite TCS material made from MgSO4 and diatomite was reported, showing improved cycle stability, enhanced sorption capacity, and thermal performance in the temperature range of 80-150 degrees C.
Article
Energy & Fuels
Xianglei Liu, Yanan Song, Qiao Xu, Qingyang Luo, Yang Tian, Chunzhuo Dang, Haolei Wang, Meng Chen, Yimin Xuan, Yongliang Li, Yulong Ding
Summary: By developing nacre-like ceramics embedded with titanium nitride nanoparticles, this study successfully achieves efficient solar-to-thermal conversion and rapid energy storage. The combination of high thermal conductivity biomimetic skeletons and volumetric absorptive phase change materials significantly enhances the solar-to-thermal energy storage rate.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Energy & Fuels
Robin Fisher, Yulong Ding, Adriano Sciacovelli
Summary: Thermochemical energy storage (TCES) provides a high energy storage density for storing heat indefinitely, making it ideal for seasonal thermal energy storage (TES). Research on the hydration of inorganic salts such as K2CO3 and MgCl2 sheds light on the kinetic differences between materials, improving hydration efficiency and understanding rate-limiting mechanisms. Expanding this fundamental understanding is crucial for unlocking the full potential of TCES and developing technical solutions.
JOURNAL OF ENERGY STORAGE
(2021)
Article
Energy & Fuels
Binjian Nie, Jie Chen, Zheng Du, Yunren Li, Tongtong Zhang, Lin Cong, Boyang Zou, Yulong Ding
Summary: The research demonstrated that the composite PCMs have good cyclability and chemical stability. The addition of 4 wt.% fumed silica could eliminate PCM leakage, while adding 1 wt.% of graphene increased the thermal conductivity by 55.4%. Using the composite PCMs led to a 6.25% reduction in charging time, providing a temperature environment of 2 to 8 degrees C for up to 11.5 hours. The overall energy efficiency increased by 12.58% with the use of the composite PCMs.
JOURNAL OF ENERGY STORAGE
(2021)
Article
Energy & Fuels
Xianglei Liu, Hang Shi, Xianguang Meng, Chen Sun, Kai Zhang, Lei Gao, Yuan Ma, Zekai Mu, Yueyue Ling, Bo Cheng, Yongliang Li, Yimin Xuan, Yulong Ding
Summary: The use of NiCo alloy catalyst enables efficient solar-driven CO2 conversion with high light-to-fuel efficiency, attributing to photo-enhanced reactant activation and synergistic catalysis to inhibit carbon formation.
Article
Chemistry, Inorganic & Nuclear
M. P. Stockham, B. Dong, M. S. James, Y. Li, Y. Ding, P. R. Slater
Summary: The next generation lithium ion batteries with all solid-state architecture offer higher energy density storage to meet the demands of modern society, particularly the growing electric vehicle market. Although solid state batteries face commercial challenges, garnet materials show promise as potential contenders due to their desirable properties, but there are still obstacles to overcome. Further engineering of Hf systems may lead to additional improvements for future use in solid state batteries.
DALTON TRANSACTIONS
(2021)