Article
Mechanics
Qi Li, Jianan Zeng, Zemin Huang, Lei Wu
Summary: Two kinetic models are proposed for high-temperature rarefied gas flows with internal degrees of freedom and radiation, one using Boltzmann collision operator and the other using relaxation time approximations. These models are validated and applied to rarefied gas flows with and without radiation, revealing the influence of non-equilibrium photon transport and their interactions with gas molecules on heat transfer characteristics. The study provides insights into the tightly coupled fields of gas and radiation under different flow conditions.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Thermodynamics
Young Dal Jeong, Ki Ho Ahn, Min Je Kim, Jae Hwa Lee
Summary: This study proposes a heat transfer system to improve the thermal performance of a channel flow with wall-mounted flexible flags. The effects of the gap distance and bending rigidity on vortex dynamics are examined. The results show that the heat transfer systems under different modes can improve thermal efficiency, but the effects vary.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Physics, Multidisciplinary
Tianbai Xiao
Summary: The study proposes a well-balanced unified gas-kinetic scheme for the study of cross-scale multicomponent flows under an external force field. The scheme leverages the Boltzmann model equation to construct numerical flux functions and accurately describes flow dynamics in different flow regimes. It provides a solution for long-term evolving systems and proves its well-balanced property through theoretical analysis and numerical validations.
Article
Thermodynamics
R. Siddharth, Shaik Subhani, Rajendran Senthil Kumar
Summary: The study investigates the flow and heat transfer characteristics of two hot circular bodies in a 2D simulation. By optimizing the geometry, maximum heat dissipation can be achieved. The positioning of the cylinders in the enclosure has a significant impact on heat transfer rate.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Chemistry, Multidisciplinary
Yuting Guo, Haiyi Sun, Meng An, Takuya Mabuchi, Yinbo Zhao, Gaoyang Li
Summary: This study combines molecular dynamics simulation, multi-attribute point cloud dataset, and deep learning network to map anisotropic wetting surfaces to the static and dynamic behaviors of water molecules and predict water transport behavior. A nanoparticle tracking optimization strategy is proposed to improve the prediction of chaotic water molecule flow. The results demonstrate the superior performance of the deep learning framework in terms of accuracy, computational cost, and visualization, and its potential for modeling different molecular transport behavior. This research is expected to promote the development of real-time water flow prediction at interfaces and contribute to surface structure optimization and design in nanofluidic devices.
Article
Thermodynamics
Mohammad Athar Khan, Saif Masood, Syed Fahad Anwer, Saleem Anwar Khan, Md. Reyaz Arif
Summary: In this study, the combined effect of buoyancy and flow approach angle on vortex-induced vibration of an elastically mounted square cylinder was numerically investigated. The results showed that the lock-in regime occurred between Ured = 5 and 6 for all flow approach angles. Different vortex shedding modes were observed, and the drag coefficient and Nusselt number were found to peak at α = 45 degrees. The study also showed that as α increased, the drag coefficient and Nusselt number increased due to larger heated surface area exposure to the fluid particles. The highest Nusselt number was observed at Ured = 6, α = 45 degrees for Ri = 0.5.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Multidisciplinary Sciences
Umar Farooq, Hassan Waqas, Nahid Fatima, Muhammad Imran, Sobia Noreen, Abdul Bariq, Ali Akgul, Ahmed M. Galal
Summary: The dominant characteristics of hybrid nanofluids, such as rapid heat transfer rates, superior electrical and thermal conductivity, and low cost, have attracted the interest of researchers worldwide. This study investigates the effects of a silver and cobalt ferrite-based hybrid nanofluid with MHD between a rotating disk and a cone. By utilizing similarity transformations, the set of partial differential equations is transformed into a set of ordinary differential equations. The volume proportion of nanoparticles and the temperature distribution profile are found to increase, making this hybrid nanofluid more efficient for metallurgical, medicinal, and electrical applications. Additionally, the antibacterial properties of silver nanoparticles can be utilized for bacteria growth inhibition.
SCIENTIFIC REPORTS
(2023)
Article
Multidisciplinary Sciences
Hussam Alrabaiah, Muhammad Bilal, Muhammad Altaf Khan, Taseer Muhammad, Endris Yimer Legas
Summary: This study addresses the flow of a hybrid nanofluid consisting of silver, magnesium oxide, and gyrotactic microorganisms inside a conical space between a disc and cone and its impact on thermal energy stabilization. The effects of different rotation directions and the introduction of magnetic field factors and nanoparticulate are investigated. The results show that the thermal energy profile is greatly improved by the magnetic effect, the addition of nanoparticulate, and an appropriate Eckert number.
SCIENTIFIC REPORTS
(2022)
Article
Multidisciplinary Sciences
Humaira Sharif, Bagh Ali, Imran Siddique, Iqra Saman, Mohammed M. M. Jaradat, Muhammad Sallah
Summary: This study analyzes the momentum and thermic aspects of MHD Ellis ternary nanomaterial embedded with dust particles using a stretchable Riga plate. The flow equations are converted into dimensionless nonlinear ODEs to obtain graphical results. The study investigates the velocity and temperature profiles, as well as evaluates the Nusselt number and skin friction. The findings show that the thermal transport performance of the trihybrid nanophase is better than that of the dusty phase, with rotational and volume fraction dust particles parameters leading to increased temperature distribution.
SCIENTIFIC REPORTS
(2023)
Article
Thermodynamics
Zhao Song, Xueshuo Shang, Zheng Cui, Yu Liu, Qun Cao
Summary: The high integration of electronic devices is an ongoing trend, but the bottleneck lies in the heat dissipation in micro/nanoscale. Surface roughness and wettability are two key factors affecting convective heat transfer in nanochannels. By conducting molecular dynamics simulations, this study investigates how wettability and roughness combined influence heat transfer and flow characteristics in rectangular nanochannels. The results show that increased hydrophilicity and subdivision of the surface lead to improved heat transfer efficiency, as evidenced by increased temperature and Nu values. However, this also results in reduced temperature slip and increased flow resistance, inhibiting fluid flow. The effects of wettability and roughness are inconsistent, with wettability having a slight hindrance on velocity development but significant improvement on temperature development.
APPLIED THERMAL ENGINEERING
(2023)
Article
Chemistry, Physical
Haiyi Sun, Man Wang
Summary: This study provides atomistic insights into the heat transfer and flow behaviors of nanofluids in nanochannels using molecular dynamics simulation. It is found that nanoparticles in nanofluids can affect temperature development and fluid flow, promoting heat transfer. Nanofluids with higher nanoparticle volume concentration exhibit better convective heat transfer performance.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Mechanics
Yanli Chen, Wenwen Jiang, Xueqing Zhang, Yuanyuan Geng, Guiqiang Bai
Summary: By linking the fractional operators to the microstructure of pore porous media, this study develops a spatial fractional permeability model and a fractional thermal conductivity model for non-Newtonian fluids in porous media. The accuracy of these models is higher than that of the conventional capillary model and they reveal the relationship between nonlocal memory and microstructural properties of complex fluids.
Article
Thermodynamics
Qifeng Zhu, Yangyang Jin, Junjie Chen, Ruirui Su, Feiyue Zhu, Haixia Li, Jianfeng Wan, Hongwei Zhang, Haolei Sun, Yang Cui, Huixue Xia
Summary: The combination of cavities and ribs significantly affects the performance and efficiency of microchannel heat sink systems. Optimizing the shape and position of ribs is crucial for minimizing pressure drop and maximizing heat removal efficiency. Different shapes and dimensions of ribs have a noticeable impact on the overall system performance.
APPLIED THERMAL ENGINEERING
(2021)
Article
Thermodynamics
D. Padrao, D. Hancock, J. Paterson, F. Schoofs, C. Tuck, I. Maskery
Summary: This study numerically analyzed the hydraulic and thermal performance of five surface-based lattice structures and developed predictive models for pressure drop and volumetric heat transfer coefficients. The research found that the thermal performance of the surface-based lattices is dependent on the internal geometry, with structures capable of distributing thermal energy across the entire fluid volume having higher heat transfer coefficients.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Diego Alcaniz, Paolo Caccavale, Maria Valeria De Bonis, Ruth de los Reyes, Maria Dolores Ortola, Gianpaolo Ruocco
Summary: A new fluid heater based on BCET was proposed in this paper, with fully-dimensional thermo-fluid analysis implemented to achieve more uniform and effective heat transfer to temperature-sensitive working fluids. Through geometry optimization with internal baffles, the uncontrolled temperature excess was significantly reduced, while the pressure drop across the flow device was also lowered.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Engineering, Multidisciplinary
Y. Egami, Y. Hasegawa, Y. Matsuda, T. Ikami, H. Nagai
Summary: A fast-responding pressure-sensitive paint (fast-PSP) has been developed for measuring time-resolved small pressure fluctuation on model surfaces. By mixing silicone and titanium dioxide particles of different sizes, a novel PSP with fast response, high robustness, and high luminescence intensity has been created, allowing for accurate pressure fluctuation data even at high mean velocities of 20 m/s.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2021)
Article
Mechanics
Hiroki Yamaguchi, Gota Kikugawa
Summary: This research studied thermal transpiration flow through a two-dimensional channel with nanoscale clearance using the molecular dynamics method, adopting two Knudsen number conditions by changing the width of the computational cell. The results showed that thermal transpiration flow can occur even under dense gas conditions, inducing flow in the adsorption layer of gas molecules on the channel wall in the height direction.
Article
Physics, Multidisciplinary
Ryo Iwao, Hiroki Yamaguchi, Tomohide Niimi, Yu Matsuda
Summary: The curing process of PDMS was investigated using single-molecule tracking method, showing discrepancies between time- and ensemble-averaged mean square displacements, indicating weak ergodicity breaking, as well as heterogeneous distribution of diffusion coefficient.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2021)
Article
Mechanics
Tomoki Inoue, Yu Matsuda, Tsubasa Ikami, Taku Nonomura, Yasuhiro Egami, Hiroki Nagai
Summary: The study proposes a noise reduction method for unsteady pressure-sensitive paint (PSP) data based on modal expansion, determining coefficients from optimally placed points. The method effectively reduces noise and accurately reconstructs pressure data, demonstrating applicability to various types of experimental data.
Article
Engineering, Aerospace
Masayuki Anyoji, Fujio Akagi, Yu Matsuda, Yasuhiro Egami, Taro Handa
Summary: A novel device enhances supersonic mixing through changes in flow structure, with experimental results confirming the vortex effect and pressure oscillation observed in computational results.
Article
Engineering, Mechanical
Hikaru Sugisaki, Chungil Lee, Yuta Ozawa, Kumi Nakai, Yuji Saito, Taku Nonomura, Keisuke Asai, Yu Matsuda
Summary: A high-spatial resolution measurement system based on the background-oriented schlieren (BOS) method is proposed in this note. The system utilizes the single-pixel correlation method to calculate the displacement obtained from the BOS method, and is compared with the conventional method. The results show that the proposed system can obtain displacement distribution with higher resolution.
EXPERIMENTS IN FLUIDS
(2022)
Article
Thermodynamics
Hiroki Yamaguchi, Taiki Mori, Yuki Ozaki, Yu Matsuda, Tomohide Niimi
Summary: The study focuses on the accommodation coefficients of water molecules in gas-surface interaction. The thermal accommodation coefficient (TAC) and tangential momentum accommodation coefficient (TMAC) of water molecules are measured. The results show that the accommodation coefficients of water are slightly larger than those of noble gases.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Analytical
Yu Matsuda, Riki Orimo, Yusaku Abe, Yuri Hiraiwa, Yosuke Okamura, Yuta Sunami
Summary: The translation provides an understanding of Pressure-Sensitive Paint (PSP) as a technique to measure pressure distribution by measuring the emission intensity of the PSP coating, with the use of organic solvents and applying skill affecting its properties.
Article
Chemistry, Analytical
Ryo Iwao, Hiroki Yamaguchi, Makoto Obata, Yu Matsuda
Summary: Polymer chains in solutions of different concentrations exhibit stretching and compression under shear flow conditions, which is different from classical theory. FRET measurement is a promising diagnostic method for understanding the dynamics of polymer chains.
Article
Mechanics
M. V. Johansson, M. Wuest, P. Perrier, I. Graur
Summary: The gas flow through low permeability porous media is widely studied for its applications in vacuum technology. It can provide high mass flow rate and rarefaction. In this study, a transient experimental technique is used to directly measure the permeability and conductance through pressure variation measurements. The results show that this methodology provides higher accuracy compared to other commonly used methods. The analysis also reveals the characteristic pore size of the sample and the achievement of constant conductance in free molecular flow regime.
Article
Thermodynamics
Martin V. Johansson, Keshvad Shahrivar, Hiroki Yamaguchi, Frederic Topin, Pierre Perrier, Irina Graur
Summary: The steady state characteristic of the transient temperature gradient driven flow through a microporous ceramic medium, known as the Thermomolecular Pressure Difference (TPD), is experimentally analyzed for five gases, including helium, neon, nitrogen, argon, and krypton. The pressure relaxation time and mass flow rate through the medium are extracted from the transient pressure measurements. The mass flow rate of helium shows a Gaussian type shape and a quasi analytical expression is proposed for the relaxation time. The experimental characterization of temperature driven flow has potential implications for the development of Knudsen pumps.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2023)
Article
Thermodynamics
Gbocho Gilles Soboh, Quy-Dong To, Irina Graur, Frederic Topin, Vincent Monchiet, Celine Leonard
Summary: In this paper, the Molecular Dynamics method was used to simulate the equilibrium vapor-liquid methane and investigate the condensation process and momentum exchange at the atomic level. By analyzing various parameters, the mass and velocity accommodation coefficients can be determined. The results are influenced by temperature, film thickness, and collision rate.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Chemistry, Analytical
Kyosuke Suzuki, Tomoki Inoue, Takayuki Nagata, Miku Kasai, Taku Nonomura, Yu Matsuda
Summary: This paper proposes a markerless image alignment method for pressure-sensitive paint measurement data, which improves the efficiency and alignment accuracy compared to the time-consuming conventional method. The results show that the proposed method performs equally well as the difference of Gaussian detector, while the image alignment using black markers and Hessian corner detector has slightly worse performance.
Article
Physics, Fluids & Plasmas
Tommaso Missoni, Hiroki Yamaguchi, Irina Graur, Silvia Lorenzani
Summary: In this paper, an analytical expression for the first- and second-order thermal slip coefficients is provided based on the true linearized collision operator for hard-sphere molecules. The influence of the gas-surface interaction and accommodation coefficients on the slip parameters is considered. The unique pair of accommodation coefficients is determined through a two-step process, taking into account experimental data and theoretical results for a fair agreement. Additionally, it is confirmed that both accommodation coefficients increase with the molecular weight of the gases considered, as previously observed in the literature.
