School of Energy and Power Engineering
Xi'an Jiaotong University, China
|Biography: Wen-Quan Tao is a Professor at Key Laboratory of Thermo-Fluids Science & Engineering of MOE, and Int. Joint Research Laboratory of Thermal Science & Engineering, Xi’an Jiaotong University, China. He graduated from Xi’an Jiaotong University in 1962 and received his graduate Diploma in 1966 under the supervision of Professor S.M.Yang. From 1980 to 1982 he worked with Professor E.M.Sparrow as a visiting scholar at the Heat Transfer Laboratory of University of Minnesota. He was selected as the member of Chinese Academy of Science in 2005. He has published more than 300 papers in international journals and 8 books in heat transfer and numerical heat transfer, among which the book titled by Numerical Heat Transfer has been cited more than 14000 times home and abroad. He has supervised more than 140 graduate students. His recent research interests include multiscale simulations of fluid flow and heat transfer problems , thermal management and performance enhancement of PEMFC, cooling technique of data center ,thermal energy storage and saving, and enhancement of heat transfer.|
|Title: Development of VOSET and it’s Applications in Simulation of Flow Boiling in a Mini-tube|
|Abstract: In this lecture the numerical method VOSET for the interface capturing is first briefly introduced, including the basic concept , major steps of implementation and and its development from 2 D to 3 D. Then a three-dimensional conjugated numerical simulation is conducted to investigate subcooled flow boiling in a horizontal rectangular mini-channel by VOSET. A reasonable nucleation density site model based on experimental results is adopted. Hundreds of bubbles with different sizes are successfully captured. Simulation results reproduce typical processes of subcooled boiling flow: bubble growth, coalescence, detachment, and condensation. In addition different flow boiling patterns, from pseudo bubbly flow to slug flow are visualized under different heat fluxes. The effects of heat flux and vapor fraction on heat transfer coefficient are discussed. The heat transfer deterioration is observed at high heat flux because of the formation of dry patches.|
Department of Mechanical Engineering
Tokyo University of Science, Japan
|Biography: Dr. Makoto Yamamoto received his BS, MS and Ph.D. in Mechanical Engineering from the University of Tokyo in 1982, 1984 and 1988, respectively. He previously worked at the IHI Corporation in Tokyo as an aerodynamic design engineer of a jet engine for about 3 years. Then he joined the Tokyo University of Science in 1990. Since 2004, he has been a professor. In the university he was a dean of the Faculty of Engineering from 2009 to 2010, and a vice president from 2014 to 2018. Since 1980s’, he has been investigating modeling of flow physics and its application to engineering problems, and recently he has been focusing on multi-physics flow problems in engineering, especially in a jet engine. Moreover, he is now challenging predictions of aneurysm rupture and surgery operations such as coiling and stenting. He is a member of various academic society such as JSME, GTSJ, JSFM, JSCES, IAESTE, FSP, JACM, IACM, ASME and SAE. He served a lot of Executive Committees of the societies, and he is now the president of JSFM. For his distinguished works he has received 13 awards from the societies and the government.|
|Title: Multi-physics CFD simulation of deposition phenomenon in a jet engine|
|Abstract: Deposition phenomenon occurs in a jet engine, when a jet engine is operated in a particulate environment such as yellow sand or volcanic ash clouds. The ingested sand or ash is melted in a combustion chamber and becomes a small droplet because the temperature exceeds the melting point of the particles. Since turbine components are colder than the droplet, some droplets adhere and accrete on the surfaces. The deposition phenomenon does not only lead to deterioration of the turbine aerodynamic performance, but also shorten the life time of the turbine. Therefore, the prediction and understanding of the deposition phenomenon are of importance in the design and development phases of a jet engine. The objectives of the present study are to numerically predict the deposition phenomenon on a turbine vane with a grid-based method, and also to investigate the deposition phenomenon of a single droplet with a particle-based method. In the grid-based simulation, the finite volume method and semi-empirical deposition model were used, and in the particle-based method, the E-MPS method was employed to simulate the solidification of a droplet. In the presentation, the detail of numerical procedures will be explained, and then some typical results will be introduced.|
Mechanical & Aerospace Engineering
Hong Kong University of Science and Technology, Hong Kong, China
Biography: (within 200 words)
Professor Zhao is an elected academician of the Chinese Academy of Sciences, the Cheong Ying Chan Professor of Engineering and Environment, Chair Professor of Mechanical & Aerospace Engineering at HKUST, the Director of the HKUST Energy Institute, and a Senior Fellow of the HKUST Institute for Advanced Study. He is a Fellow of the American Society Mechanical Engineers (ASME), Fellow of the Royal Society of Chemistry (RSC), and a Highly Cited Researcher by Clarivate/Thomson Reuters (2014, 2015, 2016, 2017, 2018, 2020), and Editor-in-Chief of International Journal of Heat and Mass Transfer.
Professor Zhao’s research has focused on heat transfer, fuel cells, and batteries. n addition to five books/monographs, nine book chapters, and more than 70 keynote lectures at international conferences, he has published 380 papers in various prestigious journals. These papers have collectively received more than 22,100 citations and earned Prof. Zhao an h-index of 78 (Web of Science).
In recognition of his research achievements, Prof. Zhao has received many awards, including the 2014 Distinguished Research Excellence Award (HKUST), a named professorship in Engineering and Environment, two State Natural Science Awards, the 2018 Ho Leung Ho Lee Prize for Scientific and Technological Progress, the Croucher Senior Fellowship award, the Overseas Distinguished Young Scholars Award (NSFC), and the Commemorative Medal for the 70th anniversary of the People’s Republic of China.
|Title: Three-dimensional electrochemical-thermal coupled modeling of lithium-ion batteries|
|Abstract: The operation of lithium-ion batteries will generate a large amount of heat, especially at high charge/discharge rates. The accumulation and distribution of heat will cause temperature rise and thus affect the electrochemical reactions, which in turn, impact the heat generation. Fundamental understanding of the interactive electrochemical and thermal characteristics of lithium-ion batteries is thus essential for the design and development of thermal management systems. In this talk, we will present a three-dimensional model by coupling ion transport, electrochemical reactions, and heat transfer. The heat generation rate calculated by the electrochemical model is applied to the thermal model as the heat source, while the temperature derived from the thermal model is regarded as the initial condition for the electrochemical model. After verifying the simulation with experimental dataat different discharge rates, the distributions of lithium-ion concentration, current density, overpotential, heat generation rate, and temperature against discharge time are numerically investigated. The effect of the average particle size of electrodes on the heat generation rate of the battery during the discharge process is studied. The fundamental cause of the non-uniform distribution of heat generation and temperature is also revealed.|
Shin Hyung Rhee
Department of Naval Architecture and Ocean Engineering
Seoul National University, Korea
Biography:For the last thirty years since his graduate study, Prof. Rhee passionately dedicated his career to Computational Fluid Dynamics (CFD) technology development for real-world applications. Prof. Rhee’s mainstream research topic is naval hydrodynamics and he developed and shared CFD codes for many different naval applications. As an engineering professor, Prof. Rhee considers his profession as a way to both satisfy his own curiosity and materialize new ideas. He is a Fellow of both the Society of Naval Architects and Marine Engineers (SNAME), USA, and the Royal Institution of Naval Architects, UK. He translated a book published by SNAME to Korean and authored two books. He published 74 international peer reviewed journal papers and registered 19 patents in the US and Korea.
Title: Modified partially-averaged Navier-Stokes models for secondary flows around a ship hull
|Abstract: Modified formulations of the partially-averaged Navier-Stokes (PANS) model were suggested for accurate prediction of the secondary flow by resolving the anisotropy of turbulence. The main characteristics of the modified PANS (mPANS) models were to resolve the wide range of turbulent length scale by decreasing fk value in the region where the anisotropic behavior of turbulence dominates. The information on the region, where there is highly anisotropic turbulence, was procured by using the budget analysis and the anisotropy invariant map. The level of how much fk should be reduced was determined by model factors, which were set to be able to resolve the secondary flow in a square duct and around a prolate spheroid. To identify the reliability of the model factors, the mPANS models were applied to the flow around the KRISO very large crude oil carrier at Froude number of 0.142. The mPANS models showed improved predictions of the hook-shape pattern of the streamwise component of velocity and secondary vortex on the propeller plane compared to the original PANS (oPANS) results by decreasing the modeled turbulent kinetic energy.|
School of Mechanical Engineering
Kookmin University, Korea
Biography: Professor, School of Mechanical Engineering, Kookmin Universkty, Seoul, Korea (2010~)
Senior Researcher, Korea Institute of Energy Research (2006~2010)
Postdoctoral Research Fellow, Mechanical Engineering, The University of Tokyo, Japan (2004~2006)
Ph.D., School of Mechanical and Aerospace Engineering, Seoul National University, Korea (2003)
M.S., School of Mechanical and Aerospace Engineering, Seoul National University, Korea (1999)
B.S., Department of Mechanical Engineering, Seoul National University, Korea (1997)
Title: Large eddy simulation of film cooling involving periodic pressure pulsation
|Abstract: The effects of flow unsteadiness, especially periodic pressure pulsation, on film cooling in gas turbine blades were investigated by conducting large eddy simulation. The film cooling flow fields from a cylindrical hole and triple holes inclined 35° to a flat plate at the average blowing ratio of M = 0.5 and 1.0 were numerically simulated. The effect of pressure pulsation at the Strouhal number from 0.1 to 1.6, which is typical in gas turbines, was examined. The LES results were compared to the experimental data of Seo, Lee, and Ligrani (1998) and Jung, Lee, and Ligrani (2001). The credibility of the LES results relative to the experimental data was demonstrated through a comparison of the time-averaged adiabatic film cooling effectiveness, time- and phase-averaged temperature contours, time-averaged velocity profiles and turbulence intensities. The adiabatic film cooling effectiveness predicted using LES agreed well with the experimental data, whereas RANS highly overpredicted the centerline effectiveness. RANS could not properly predict the injectant topology change in the streamwise normal plane, but LES reproduced it properly. The triple-hole system was found to be better for film cooling than a single-hole system for higher values of the pulsation Strouhal number.|
Department of Mechanical Systems Engineering
Tokyo University of Agriculture and Technology, Japan
Biography: Kaoru Iwamoto received his B. Eng., M. Eng. and Dr. Eng. degrees all from the University of Tokyo, Japan in 1999, 2001 and 2004, respectively, under the supervision of Prof. Nobuhide Kasagi. He was a postdoctoral fellow of Japan Society for the Promotion of Science at the University of Tokyo in 2004, a research associate at Tokyo University of Science in 2005-2006 and an associate professor at Tokyo University of Agriculture and Technology in 2007-2017. Since 2018, Dr. Iwamoto has been a full professor of the Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, Japan. He was the department chair in 2019. His research interests include understanding and controlling wall turbulence and turbulent heat transfer. On those topics, he has published about 60 refereed journal papers, about 130 international conference papers and about 20 review papers. His invited or keynote lectures are about 25 and he has won 7 awards from different institutions including Paper Award of Japan Society of Fluid Mechanics, and the Young Scientists' Prize, the commendation for science and technology by the Minister of Education, Culture, Sports, Science and Technology, Japan.
|Title: Wall Turbulence Control for Drag Reduction and Heat Transfer Enhancement Based on Biomimetics and Deep Learning|
|Abstract: Development of efficient turbulence control techniques for drag reduction and heat transfer augmentation is of great importance from the viewpoint of energy saving and environment impact mitigation. In our laboratory, basic technologies for energy saving have been developed by reducing energy loss owing to turbulent friction drag on high-speed transportation systems such as airplanes and high-speed trains which are indispensable tools for construction of a secure, safe and comfortable society. Specifically, world's largest super-parallel turbulent simulations and laboratory experiments using high-speed cameras and laser sheets are being performed to evaluate our efficient and unique biomimetic control technologies. First, we have developed a unique three-dimensional riblet by further developing shark skins. We have confirmed a world-leading drag-reduction effect of about 12%. Second, we demonstrated the drag-reduction effect of a micro-vibration traveling wave surface simulating dolphin’s skin for the first time in the world. Furthermore, we have been developing a new ship-bottom paint with drag-reduction polymer that simulates secretions of fish such as catfish, and a fluid-pulsating control by applying the principle of blood flow pulsation and deep learning. As for heat transfer enhancement, the convection in a pipe with transverse vibration was newly investigated. The Nusselt number periodically increases and decreases in time to achieve 70% augmentation on average. Our unique biomimetic control techniques are feasible solutions for the near future, and could contribute to significant progress in turbulence engineering.|
Professor Jae Hwa Lee
Department of Mechanical Engineering
Ulsan National Institute of Science and Technology, South Korea
Biography: Prof. Lee received Ph.D. in Mechanical Engineering from Korea Advanced Institute of Science and Technology (KAIST) in 2012. He is currently an Associate Professor in the Department of Mechanical Engineering at Ulsan National Institute of Science and Technology (UNIST), Korea.
Title: Artificial neural network-based wall-models for large-eddy simulations of turbulent flows
|Abstract: Wall-modeling approach in large-eddy simulation (LES) is necessary to alleviate the huge near-wall resolution requirements for high Reynolds number turbulent flows. However, because most existing wall-models either neglect non-equilibrium effects or require fine grids along the wall-normal direction, we propose artificial neural network-based wall-stress models (AWMs). An important feature of the AWMs is the accurate prediction of the wall-shear stress in complex flows (e.g. a separated flow) because input variables of the AWMs extracted from decomposition of skin-friction coefficient proposed by Fukagata et al. (Phys. Fluids vol. 14, 2002, pp. 73-76) can capture all non-equilibrium effects (i.e. unsteadiness, convection and pressure gradient effects). In addition, the AWMs have very high computational efficiency because they only use the outer layer information to obtain the wall-shear stress. The performance of the AWMs is tested for both a fully developed turbulent channel flow and a separated turbulent boundary layer flow. A direct comparison of turbulent statistics (e.g. skin-friction coefficient, mean velocity and Reynolds stresses) with those by previous existing wall-models, such as the log-law-based model (Yang et al. Phys. Rev. Fluids vol. 2, 2017, 104601) and the non-equilibrium model (Park & Moin, Phys. Fluids vol. 26, 2014, pp. 37-48) demonstrates that the AWMs provide better prediction performance for two types of flows, even at untrained Reynolds numbers. When a coarse grid resolution in the wall-normal direction is used for a turbulent channel flow, the AWM shows upward shift of the mean streamwise velocity profile (i.e. positive log-layer mismatch, LLM) compared to the DNS data. This problem is overcome by imposing wall-normal velocity at the wall that is dynamically calculated using the continuity equation and the Taylor series expansion using the wall-adjacent cells. This non-zero wall-normal velocity at the wall also improves prediction performance of the near-wall turbulence for a separated turbulent boundary layer flow.|
C. N. Markides
Department of Chemical Engineering
Imperial College London, United Kingdom
Biography:Christos Markides is Professor of Clean Energy Technologies, Head of the Clean Energy Processes Laboratory, and leads the Experimental Multiphase Flow Laboratory, which is the largest experimental space of its kind at Imperial College London.. He is also, amongst other, Editor-in-Chief of ‘Applied Thermal Engineering’. He specialises in applied thermodynamics and transport processes as applied to high-performance devices, technologies and systems for thermal-energy recovery, utilization, conversion or storage, and an ongoing interest in advanced diagnostic techniques for the provision of detailed, spatiotemporally resolved information in turbulent, reacting and multiphase flows. He has published >250 journal papers and >300 conference papers on these topics and won multiple awards, including: IMechE’s ‘Donald J. Groen’ outstanding paper prize in 2016, IChemE’s ‘Global Award for Best Research Project' in 2018, and the Engineers without Borders ‘Chill Challenge’ in 2020. He also received Imperial College President’s Awards for Teaching Excellent in 2016 and Research Excellence in 2017.
|Title: Detailed measurements as a complemtary tool to computational investigations of multiphase flows: Spatiotemporally-resolved data for advanced model development, validation and new physical insight|
|Abstract:Multiphase, and in particular two-phase, flows are encountered in a broad range of settings, from highly complex isothermal flows in upstream and midstream oil-and-gas applications, to flows in the presence of heating or cooling and phase change such as in heat exchangers, condensers, evaporators, absorbers and reactors in diverse industrial processes across a wide range of scales.|
Despite the numerous and well-performed experimental studies encountered in literature, only a limited number of studies relating to the simultaneous and spatiotemporal variations of the interfaces and underlying physical processes in these flows are currently available; a limitation linked inherently to the many challenges that arise when performing these measurements. Two-phase flows, in particular, present the experimentalist with a unique set of characteristics, including restricted (often sub-mm) fluid domains, moving and complex interfaces, and phases with large density or refractive index changes that render the extraction of reliable information challenging.
Experimental techniques based on optical measurement principles have experienced significant growth in recent decades. They are able to provide detailed information with high spatiotemporal resolution on important scalar (e.g., temperature, concentration, phase) and vector (e.g., velocity) fields in different flows, as well as interfacial characteristics. This has been instrumental to step-changes in our fundamental understanding of these flows, and to the development and validation of advanced models with ever-improving predictive accuracy and reliability. Relevant techniques rely upon optical methods such as direct photography, laser-induced fluorescence, laser Doppler velocimetry/phase Doppler anemometry, particle image/tracking velocimetry, and variants thereof.
In this talk, we will discuss recent efforts to develop and apply a range of infrared, laser-based and other optical diagnostic techniques to a range of multiphase flows, including in the presence of heat transfer and phase change. We will cover the deployment of simultaneous techniques for the generation of multi-physics, multi-field and multi-scale information, discuss the specific challenges faced when attempting to perform such measurements in select flows, and present a future outlook for these methods that will enable an increasingly complete fundamental understanding of relevant underlying phenomena, and the design of improved devices, technologies and systems.
Faculty of Engineering
Niigata University, Japan
Biography: Koji Matsubara received his B.Eng. and M. Eng. degrees in Mechanical Engineering from Kyoto University, Japan in 1990 and 1992, respectively. He got D. Eng. degree from Kyoto University under the supervision of Prof. Kenjiro Suzuki in 1996. He started his carrier and has been a professor since 2012 in Niigata University. His research interests include turbulent heat transfer with multi-scale hierarchy, radiative transfer of porous medium and high-temperature solar receiver. On those topics, he published more than 60 refereed papers in high-quality journals. He has patented technologies on high-temperature solar thermal usage. He currently serves as a leader for R & D project for solar receiver/reactor for carbon dioxide decomposition supported by NEDO (New Energy and Industrial Technology Development Organization). For international conferences, he chairs 11th SOLARIS 2021 held in Tokyo.
|Title: Conjugate radiation-convection-conduction simulation of solar porous receiver and its application for solar energy storage by hydrogen production|
Abstract: Radiation-convection-conduction interactive heat transfer in solar porous receiver has been analyzed through direct numerical simulation. In contrast to the conventional continuum-model approach, the present study simulated a gas stream and its heat transfer bounded by a real shape of the internal passage in porous material with external irradiation. Full interaction between radiation, convection and conduction was considered by the SIMPLE algorithm coupled with the DOM (Discrete Ordinate Method) as a radiation solver. The numerical result demonstrated that the very high porosity (> 90%) and the small cell size (< 1.0mm) were essential for highly efficient conversion of external irradiation to the sensible enthalpy. The fundamental finding is now utilized to design a new solar reactor for solar hydrogen production using thermochemical water splitting.
Department of Mechanical Engineering
National University of Singapore, Singapore
Biography: Dr Chang Shu is a Professor at the Department of Mechanical Engineering, National University of Singapore. He got his BEng and MEng respectively in 1983 and 1986 from Nanjing University of Aeronautics and Astronautics, China, and his PhD in 1991 from the University of Glasgow, UK. Dr Shu has been working in the computational Fluid Dynamics (CFD) for more than 35 years. His major interest is to develop efficient numerical methods to solve heat transfer and fluid flow problems, which are governed by a set of partial differential equations. Recently, he developed a series of flux solvers, which are based on the lattice Boltzmann equation and Boltzmann equation. These solvers can be well applied to simulate fluid flows from incompressible regime to hypersonic regime on structured and unstructured meshes. He also made effort to develop some efficient models for simulation of multiphase flows and flows around moving boundaries. So far, he has authored 4 monographs and published more than 350 articles in the international referred journals (SCI indexed). His work has been cited more than 20000 times in Google Scholar.
|Title: Lattice Boltzmann Flux Solver-Immersed Boundary Method and Its Applications in Heat Transfer and Fluid Flows|
|Abstract: This talk will introduce our recently developed lattice Boltzmann flux solver-immersed boundary method (LBFS-IBM) for simulation of incompressible heat transfer and fluid flows. LBFS is to combine advantages of conventional Navier-Stokes (N-S) solver and lattice Boltzmann method (LBM). It applies the finite volume method (FVM) to discretize the macroscopic governing equations given from the physical conservation laws, and reconstructs numerical fluxes at the cell interface by local solution of lattice Boltzmann equation from the macroscopic flow variables at two cell centers. LBFS removes the drawbacks of conventional LBM and N-S solver such as tie-up of mesh spacing and time interval in LBM and discretization of spatial derivatives in N-S solver. It can be easily applied to predict the flow field on both structured and unstructured meshes. The interaction between the fluid and the solid boundary will be considered by the boundary condition-enforced immersed boundary method (IBM). The essence of IBM is to consider the effect of solid boundary through the forcing term in the moment equation. This idea can also be extended to consider the thermal effect by adding a heat source term in the energy equation. The developed LBFS-IBM will be validated by its application to simulate various isothermal and thermal flow problems. The obtained numerical results compare very well with available data in the literature. It demonstrates that LBFS-IBM can be well applied to simulate practical heat transfer and fluid flows.|
Computational Transport Phenomena Laboratory,
King Abdullah Univeristy of Science and Technology, Saudi Arabia
|Biography: Shuyu Sun is a Professor of Earth Science and Engineering, Applied Mathematics and Computational Science and Energy Resource and Petroleum Engineering, Director of Computation Transport Phenomena Laboratory at King Abdullah University of Science and Technology (KAUST). He is a founding faculty member of KAUST since 2009. He holds or held a number of adjunct faculty positions across the world, including Adjunct Faculty in Clemson University, University of Nevada at Las Vegas, Xi’an Jiao Tong University, Sichuan University, China University of Petroleum and China University of Geosciences. He obtained his Ph.D. degree in computational and applied mathematics from The University of Texas at Austin. Dr. Sun has published 400+ articles or book chapters, including 250+ refereed journal articles. Based on Google Scholar, his total citation number (as of Apr 2021) is 5867 with an h-index of 36. He has three papers recognized as “Highly Cited in Field in Web of Science”, and recently he published a book with Elsevier entitled “Reservoir Simulation: Machine Learning and Modeling”. He achieved the certification under the SPE Petroleum Engineering Certification Program, and he is also a licensed professional engineer in Texas, USA. Currently he is the president of InterPore (International Society for Porous Media) Saudi Chapter.|
|Title: A 6M Digital Twin for Reservoirs|
|Abstract:Reservoir simulation has been recognized as an efficient approach to study the reserve mechanisms and to enhance the resource discovery/recovery using a number of models and algorithms, and the significant superiority on the flexibility and efficiency compared with experimental studies has made numerical studies more popular and accepted in the current energy industry. Digital Twin (also known as DT), a comprehensive and integrated concept proposed in this century, has been extensively recognized as an effective cutting-edge approach in this intelligent and digitizing era. A number of publications have been reported in the establishment and application of digital twins in various fields, including complete-cycle management, automatic production and predictive maintenance. The concept of digital twin is believed to be easily extended to reservoir studies in which data of the reservoir geometry, fluid properties, environmental and operation conditions can all feed into the model in virtual space, and we already have a mature understanding of the underneath physical and chemical rules. By simulating the mathematically-described assets in virtual space, the petroleum enterprises can gain more operating data about routine and abnormal situations, analyze how configuration differences and operating choices translate to key performance indicator in the oil and gas production, reduce lag between project conceptualization and implementation in reservoir exploitation, run trials of loss events to learn how the systems might respond to the real conditions in the complex reservoir environment and identify the most viable strategies for real-life pilot tests. In this paper, we will introduce a digital twin platform for reservoirs with the 6M properties, i.e. the multi-scale, multi-domain, multi-physics and multi-numerics numerical modeling and simulation of multi-component and multi-phase fluid flow. A new concept of reservoir digital twin is proposed in this work, covering a wide range of engineering processes related with the reservoirs, including the drainage, sorption and phase change in the reservoirs, as well as extended processes like injection, transportation and on-field processing. The mathematical tool package for constructing the numerical description in the digital space for various engineering processes in the physical space is equipped with certain advanced models and algorithms developed by ourselves.|
Division of Mechanical and Aerospace Engineering, Graduate School of Engineering
Hokkaido University, Japan
Biography: Yutaka Tabe received his B.E., M.E. and Dr. Engineering degrees from Tokyo Institute of Technology, worked at a company for 4 years, and then joined the faculty of Mechanical Engineering at Hokkaido University in 2004. Since 2019, he has been a professor of the Division of Mechanical and Aerospace Engineering at Hokkaido University. The motivations of his research are ‘reduction in CO2 emission and development of sustainable energy systems’. The current research interests lie within transport phenomena in electrochemical energy conversion devices: polymer electrolyte fuel cell and redox flow battery, and design of social energy systems in the future. He has been appointed as an associate editor of JSME Mechanical Engineering Journal since 2020 and an editor of Thermal Science and Engineering since 2008.
Title: Analysis of water transport in PEFC gas diffusion layers for improving drainage performance using the lattice Boltzmann simulation and the scale model experiment
|Abstract: In polymer electrolyte fuel cells (PEFCs), a gas diffusion layer (GDL) is a critical component to prevent flooding and to improve the cell efficiency under high current density operation. To evaluate the liquid water transport in the GDLs, the authors developed the large-scale simulations with the lattice Boltzmann method (LBM) and the scale model experiments. The LBM is able to analyze two-phase flows in complex structures. Here, to reduce computational loads and increase the simulation areas, an LBM treating two-phases as having the same density and a maximum limit of the Capillary number that maintains flow patterns similar to the precise simulation are applied. In the experiments, enlarged GDL structures are reproduced by a 3D printer, and simulated water behavior is observed with similarity conditions satisfying the flow in the GDL. Using these methods, effective structures and wettablitily patterns of GDLs are investigated for improving the dranage performance in PEFCs.|
Department of Mechanics and Aerospace Engineering
Southern University of Science and Technology , China
Biography: Dr. Lei Wu is an Associate Professor at the Southern University of Science and Technology (China) from November 2019. He received his BSc and MSc in Physics from Zhejiang Normal University, China. After obtaining the PhD in Fluid Mechanics from the University of Strathclyde (UK) in 2013, he continued to work there as a postdoctoral research associate, Chancellor’s Fellow and Senior Lecturer.
His research interest is in rarefied gas dynamics, in particular the construction of efficient/accurate numerical schemes to solve the Boltzmann equation for dilute gases and the Enskog equation for dense gases, as well as the kinetic modeling for polyatomic gas flows, with applications in aerothermodynamics of space vehicles, MEMS, shale gas extraction, and multi-scale phonon transport.
Title: GSIS: a fast convergence and asymptotic preserving solver for the Boltzmann equation
|Abstract: The Boltzmann equation is widely used to describe the multiscale transport of gas and/or phonon transport, where one of the central problems is to find the steady-state solution of the Boltzmann equation quickly, which requires efficient algorithms to (i) compute the Boltzmann collision operator and (ii) find converged solutions using limited number of iterations. The first problem is tackled by the fast spectral method. For the second problem, when the Knudsen number is large, the conventional iterative scheme can lead to convergence within a few iterations. However, when the Knudsen number is small, hundreds of thousands iterations are needed, and yet the “converged” solutions are prone to be contaminated by large numerical dissipation. Recently, we put forward a general synthetic iterative scheme (GSIS) to find the steady-state solutions within dozens of iterations at any Knudsen number. The key ingredient is that the macroscopic equations, which are solved together with the Boltzmann equation and help to adjust the distribution function, not only asymptotically preserve the Navier-Stokes limit, but also contain the Newton’s law for stress and the Fourier’s law for heat conduction explicitly. For these reasons, the constraint that the spatial cell size should be smaller than the mean free path of gas molecules is removed, making the GSIS a truly multiscale solver. Properties of fast convergence and asymptotic preserving are rigorously proven, and several numerical examples (e.g. gas flow in porous media, multiscale phonon transport) are simulated to demonstrate the efficiency and accuracy of GSIS.|
School of Energy Power and Mechanical Engineering
North China Electric Power University, China
Biography: Prof. Jinliang Xu is the professor of North China Electric Power University (NCEPU). He got PhD in 1995 at Xian Jiaotong University, and was a postdoctor in Tsinghua University from 1995 to 1997, then worked in University of Notre Dame during 1997-2002. He joined Guangzhou Institute of Energy Conversion from 2002, and setup the Micro Energy System Laboratory there. He joined NCEPU in 2009 and founded the Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilizations. His research interest includes multiphase flow and heat transfer in micro/nano systems, advanced power generation system etc. He published more than 200 international journal papers as the corresponding author and co-authored two books. He has been the highly cited author in recent five years in Energy field. He has been the chair or co-chair for a set of academic conferences and presented 40 keynote speeches in international conferences. He was the best reviewer of the Journal of Heat Transfer, ASME in the fiscal year of 2012. He received the Natural Science Award of the Ministry of Education, China (first grade). He has been the "973" project chief scientist, Ministry of Science since 2011 and was named as the "Yangtze River Scholar" Professor by the National Ministry of education, China in 2013.
|Title: Nanobubbles in supercritical fluid: a molecular dynamics study|
|Abstract: It is of great interest whether supercritical fluids contain bubbles, and if so, to determine the pressure and temperature ranges for bubbles to exist. We investigate the spatial-time phase distribution in supercritical fluids using molecular dynamics simulations. We discover nanobubbles for pressures significantly larger than the critical pressure. This finding is against common sense that supercritical fluids do not contain bubbles but can be explained that when an amount of energy is added to the fluid, a portion of the energy overcomes molecular attraction to separate neighboring molecules. We show that supercritical fluids can be divided into three regimes, liquid-like, two-phase-like containing bubbles, and gas-like, which are interfaced by an onset pseudo-boiling temperature Ts and a termination pseudo-boiling temperature Te. We determine Ts and Te using three different approaches and find consistent outcomes that match thermodynamically determined values. Nonlinear dynamics demonstrates the chaotic behavior in the two-phase-like regime, which is similar to the two-phase regime in the subcritical domain. Our work highlights the common features of bubbles in both supercritical and subcritical pressures and establishes a strong connection between the two pressure ranges. Hence, the well-established multiphase theory in subcritical pressures can be introduced to handle complex supercritical fluids.|
School of Mechanical Engineering
Beijing Institute of Petrochemical Technology, China
Prof. Yu obtained bachelor degree of Fluid Machinery in 1994 and PhD degree of Engineering Thermophysics in 1999 from Xi’an Jiaotong University. Before joining Beijing Institute of Petrochemical Technology, he worked in National Institute of Advanced Industrial Science and Technology of Japan as a Special Research Associate and China University of Petroleum (Beijing) as a full professor. His major research interests are numerical heat transfer, heat transfer enhancement, petroleum storage & transportation, etc. He has chaired 10+ national projects including National Science Fund for Distinguished Young Scholars and 30+ provincial projects from petroleum companies and government. Prof. Yu has been invited to deliver keynote speeches for 20+ times in the international or domestic conferences. He has published 150+ refereed international journal papers as the first/corresponding author, 2 textbooks and 2 monographs. So far, nine national and provincial natural science and technology awards have been conferred to Prof. Yu due to his research achievements. In 2016, he was awarded the distinguished professor of the Nation’s Changjiang Scholars Program. Other prizes awarded to Prof. Yu include the Sun Yueqi Award of Youth Science and Technology in 2006, Mao Yisheng Youth Science and Technology Award of Beijing in 2010, etc.
|Title: Research on Thermal-hydraulic-Mechanical Coupling Model for Fractured Geothermal Reservoir|
|Abstract: Hot Dry Rock (HDR) is a kind of high temperature geothermal recourse deeply buried beneath the Earth, which is also considered as a potential alternative energy resources due to its high quality, wide distribution and huge reserves. To exploit the HDR, the low-permeability rock matrix is usually fractured to form a fractured geothermal reservoir with proper flow conductivity. The behavior of fractured geothermal reservoir during exploitation process is a typical thermal-hydraulic-mechanical (THM) coupling problem. The THM coupling numerical simulation is of great importance to the design and operation of HDR exploitation project. This report focuses on the construction of THM coupling model and the corresponding numerical solution methods. Firstly, based on the embedded discrete fracture model, the fully coupled THM model of fractured geothermal reservoir is constructed, and the coupling solution method of finite volume method and extended finite element method (FVM+XFEM) is proposed. Therefore, the coupled THM model can be solved in the structured grid system. Secondly, the improved extended finite volume method (XFVM) is proposed to solve the mechanical deformation of fractured rock mass. Therefore, the integrated FVM can be used to solve the THM coupled model. Finally, to further improve the numerical efficiency of THM coupled model, an acceleration technique combining local model reduction method (MsFV) and global model reduction method (POD) is proposed.|
September 23-26, 2021
Deadline for online registration
September 20, 2021
China University of Petroleum (East China)
Xi’an Jiaotong University