Abstract: For many fluid problems it is in principle straight forward to represent the detailed problem through a molecular representation that will consistently represent the correct physics including fluctuations leading to nucleation phenomena. Representing these systems in larger scale continuum representations is not always straight forward. In this talk I present a coarse-graining procedure that maps an MD simulation onto a lattice gas. This lattice gas can then be ensemble-averaged to obtain a lattice Boltzmann representation that constitutes a first-principles derivation of lattice Boltzmann. This first-principles representation can then be analyzed and compared to existing multi-phase implementations of lattice Boltzmann to suggest a consistent path of developing multi-phase simulation methods.

Short resume: Prof. Alexander Wagner is an Associate Professor in the Department of Physics at North Dakota State University (NDSU) since 2008. He obtained his Ph.D. in theoretical physics from Oxford University in 1997. Following postdoctoral appointments at MIT and University of Edinburgh, he joined NDSU in 2002. Prof. Wagner specializes in computational physics, focusing on the lattice Boltzmann method for simulating fluid dynamics. He is also an Associate Editor for Physical Review E, where he oversees submissions related to computational physics. Additionally, he serves on the committee for the Discrete Simulation of Fluid Dynamics conference. Prof. Wagner has made significant contributions to the field of lattice Boltzmann methods, demonstrating their application beyond traditional Navier-Stokes systems, including fluctuating systems. He has authored and co-authored more than 50 papers in high-impact journals.

Abstract: Drag reduction in turbulent pipe by flow by the addition of polymer additives is a well-known procedure employed for reducing pumping power or increase flow rate. Flow rate increases of the order of 80% are obtained with small amounts of polymer added to the flow. Despite its use in field applications, the mechanisms responsible for reduction in friction and for the degradation of the performance of polymer additives are still the focus of current research. In the case of gas-liquid two-phase flows in pipes, polymer additives can still produce reductions in drag, although at reduced levels when compared to single phase flows. The addition of polymer additives can also affect the transition of flow regimes in two phase flow in pipes. In this lecture a review of the research conducted on drag reduction on gas-liquid two-phase flows in pipes by polymer additives will be presented. Some recent experimental results on the effect of polymer additive on flow transition from stratified to slug flow will be presented. Novel techniques for delivering encapsulated polymer additives will also be presented.

Short resume: Prof. Luis Fernando Azevedo holds a degree in Mechanical Engineering from the Pontifical Catholic University of Rio de Janeiro (1978), a master’s degree in Mechanical Engineering from the Pontifical Catholic University of Rio de Janeiro (1981) and a PhD in Mechanical Engineering from the University of Minnesota (1985). He is currently a full professor in the Department of Mechanical Engineering at the Pontifical Catholic University of Rio de Janeiro, working in the area of ​​fluid mechanics and experimental heat transfer. He develops fundamental and applied work in turbulent flow in pipelines, flow assurance in the oil industry, two-phase flow and optical methods for flow measurement.

Abstract: Diffusion bounding, a new fabrication technique for flat two-phase devices, is explored. Primely developed for the fabrication of compact heat exchangers, it consists of stacking thin grooved and/or machined plates and submitting the pile to high pressure and high temperature, in a controlled atmosphere and by a controlled time, within a special furnace. The resulting device may have internal multidimensional channels. Advantages of the fabrication procedure include easy fabrication of wick structures and easy surface treatment of channels. Examples of fabricated and tested devices, such as compact heat exchangers, heat pipes, loop heat pipes, thermosyphons, loop thermosyphons and pulsating heat pipes are presented and discussed.

Short resume: Prof. Márcia Mantelli holds a degree in Mechanical Engineering from the State University of Campinas (1982), a master’s degree in Space Engineering and Technology from the National Institute for Space Research (1985) and a Ph. D. in Mechanical Engineering from the University of Waterloo (1995). She is currently a full professor at the Federal University of Santa Catarina and is a CNPq Research Productivity Scholar – Level 1B. She has extensive experience in Mechanical Engineering, with an emphasis on Thermal Engineering, working mainly on the following topics: compact heat exchangers, thermal control of satellites, thermosyphons and heat pipes. She is a full member of the National Academy of Engineering (ANE).

Abstract: During a loss of coolant accident (LOCA), the core of a nuclear reactor loses its water inventory and, despite the automatic shutdown of the reactor, the temperature of the assemblies will rise rapidly due to the residual power produced by the core. This heat source (around 7% of the reactor’s rated power) explains the need to cool the reactor even when it is shut down. Cooling is achieved by injecting “cold” water through the bottom of the vessel, giving rise to a dispersed film flow boiling (DFFB) that spreads throughout the assembly fairly rapidly. This flow plays a vital role in the initial cooling of fuel rods that are not yet submerged and for safety reasons, we must ensure that the whole assembly can be cooled down before reaching the melting point. So, I will talk about estimation of heat and mass transfer within this particular flow.

Short resume: PhD in Fluid Mechnics (1996) after studying mechanical engineering and heat and mass transfer, Prof. Michel Gradeck is full professor at the University of Lorraine (France) since 2013. Since January 2023, he has been deputy director of the LEMTA CNRS. His research is in the fields of fluid mechanics and thermal science. For a long time, he has a special interest in cooling processes in steel making industry. For that, he developed different bench to measure boiling curve together with different industries in the field. After Fukushima accident he has been involved in national research program in nuclear safety together with CEA and IRSN to study severe accident in nuclear plants for which cooling of dewatered fuel assemblies is crucial. He is also involved in national network in the field of two-phase flows and in major international projects at European level.

Abstract: Research on convective condensation has been accelerating over the past few decades, spurred by multiple drivers such as phase-out of a variety of synthetic refrigerants due to climate change concerns, the need for compact condensers and thermal management systems, and waste heat recovery systems. This leads to a very wide parameter space of hydraulic diameters (100 µm < D < 15 mm), operating pressures (100 kPa < P < 20 MPa), fluid properties, and mass fluxes (25 < G < 1000 kg m-2 s-1). These conditions necessitate an understanding of condensation across a wide range of thermodynamic and transport properties of pure fluids (R134a, CO 2, ammonia, propane, pentane) as well as mixtures (refrigerant and hydrocarbon mixtures, ammonia-water.) Techniques for accurately measuring the high condensing heat transfer coefficients at small Dh will be presented. Flow regime maps and dimensionless transition criteria for a range of fluids with operating pressures up to the critical pressure will be discussed. Self-consistent models for condensation across this parameter space based on flow morphology and momentum, heat and mass transfer will be presented. Zeotropic mixtures present new challenges due to temperature and concentration gradients and coupled heat and mass transfer resistances in liquid and vapor phases. The applicability of engineering approximations such as the Silver-Bell-Ghaly method, as well as the more rigorous non-equilibrium methods that explicitly address the relevant resistances in both phases will be discussed. Recent developments in applying AI/ML techniques to develop reduced-order models for this wide parameter space will be presented. Also, emerging techniques such as tunable acoustic enhancement of condensation, will be briefly mentioned. The role of microscale phase change in enabling a variety of applications such as thermally driven heat pumps and carbon capture for decarbonization will be discussed.

Short resume: Prof. Srinivas Garimella is the Hightower Chair in Engineering and Director of the Sustainable Thermal Systems Laboratory at Georgia Institute of Technology. He has held prior positions as Research Scientist at Battelle Memorial Institute, Senior Engineer at General Motors Corp., and Associate Professor at Western Michigan University and Iowa State University. He conducts research in the areas of microscale phase change heat and mass transfer, vapor compression and sorption heat pumps, and heat recovery, upgrade and storage. He is a Fellow of the ASME and of ASHRAE. He is Editor of the Int. J. Air-conditioning and Refrigeration, and past Associate Editor of the ASME J. Heat Transfer and ASME J Energy Resources Technology, and of the ASHRAE SBTE Journal. He is Past Chair of the Advanced Energy Systems Division of ASME and was on the ASHRAE Research Administration Committee. He held the William and Virginia Binger Associate Professorship of Mechanical Engineering at ISU.