Invited Lecturers

Prof. R. S. Myong

Rho Shin Myong received the B.S. and M.S. degrees in the department of aeronautical engineering from the Seoul National University in 1987 and 1989, respectively. He received a Ph.D. degree in the department of aerospace engineering from the University of Michigan in 1996. Prior to the present position, he worked at the NASA Goddard Space Flight Center from 1997 to 1999 as a NRC research associate. Currently, he is a professor of the department of aerospace and system engineering at the Gyeongsang National University in Jinju, South Korea. He is an associate editor of the Communications in Computational Physics (CiCP) and an editorial board member of the International Journal of Computational Fluid Dynamics (IJCFD). His research interests include modeling (nonlinear coupled constitutive relation, Langmuir slip model) and simulation (FVM and discontinuous Galerkin) of non-equilibrium gas flow and heat transfer in space/micro/nano systems, applied aerodynamics and CFD, magneto-hydrodynamics, aircraft and wind turbine icing, and aircraft survivability.

Title and abstract of invited lecture:

What Makes Gas Micro Flows So Complicated: Non-classical Physical Laws and their Morphing into Gas-Surface Interaction

A seamless transition between macroscopic and microscopic theory has been a fundamental research subject in gas micro flows. Owing to formidable challenges in theoretical and computational aspects associated with the multi-scale nature of the problem, however, proper model is yet to be developed: the conventional Navier-Stokes-Fourier equations are inappropriate for highly non-equilibrium flows and the partial differential type higher-order equations such as the Burnett equations suffer inherent difficulty in handling the boundary condition at the solid wall. There is even no consensus what the proper master kinetic equations would be for describing diatomic gases like nitrogen in thermal non-equilibrium.
Here non-classical physics (governing equations and gas-surface interaction model) behind non-equilibrium micro gases is touched upon from the framework of nonlinear coupled algebraic constitutive relations and nonlinear boundary conditions. In particular, the effects of non-Navier-Stokes and non-Fourier laws and their morphing into gas-surface interaction are elucidated by solving various benchmark micro-flows: planar Couette (equivalently Knudsen layer), force-driven Poiseuille, and pressure-driven Poiseuille in microchannels. Of particular interests are non-classical physics of abnormal behaviors such as non-zero tangential heat flux and normal stress, pronounced thermal effect, rotational non-equilibrium effect, nonlinear velocity profile and velocity gradient singularity (Couette), Knudsen minimum (Poiseuille), non-uniform pressure and the central temperature minimum (Poiseuille), and cross-stream energy preservation (Poiseuille). In addition, a hybrid slip (jump) model combining well-known Maxwell/Smoluchowski model and recent Langmuir model based on the concept of adsorption isotherm is presented. Finally, the verification and validation issue of the multi-scale methods is discussed. As the first step, issues of micro- and macro- sampling of DSMC and its internal error in conservation laws are considered.

  

Dr. J. C. Lötters

Dr. Joost C. Lötters received the M.Sc. degree in electrical engineering from the University of Twente, Enschede, The Netherlands, in 1993 on the subject of a buffer amplifier for a piezoelectric impact sensor. In 1997 he received the Ph.D. degree in electrical engineering at the same university on the subject of a highly symmetrical triaxial capacitive accelerometer. In 1997 he joined Bronkhorst High-Tech BV, Ruurlo, The Netherlands. Since then, his research has concentrated on flow measurement and control in the field of thermal and Coriolis flow sensing. In 2010 he joined the Transducer Science and Technology (TST) group as part-time associate professor. Since then his research has focused on microfluidic handling systems. Highlights include a micromachined thermal flow sensor using thermopiles, a micro Coriolis flow sensor and a single chip flow sensing system comprising both a thermal and a Coriolisflow sensor. Joost Lötters is inventor or co-inventor of more than 10 patents and author or co-author of more than 50 journal and conference papers.

Title and abstract of invited lecture:

Integrated systems for the accurate measurement, control and analysis of micro liquid and gas flows

Worldwide, accurate measurement, control and analysis of small and extremely small mass flow rates of both gases and liquids is becoming more and more important, driven by numerous economically important applications in for instance semiconductor industry, analytical instrumentation, food, medical, pharmacy, energy, and micro reaction systems.
Necessary components for these integrated microfluidic handling systems are for instance proportional control valves, thermal flow sensors, Coriolis flow sensors, pumps, pressure sensors, temperature sensors and analysers such as gaschromatographs and Wobbe index meters. The individual components may exist, but they have never been designed from the system and industrial end-user point of view.
In this presentation, we propose to realise integrated microfluidic handling systems, composed of building blocks that are designed to fit within the system. Examples of applications in the markets as mentioned above will be given.

 

Dr. M. Bergoglio

Mercede Bergoglio was educated in the Turin University where, in 1985, she received her degree in Physics. She joined the Istituto Nazionale di Ricerca Metrologica (INRIM, Strada dellecacce 91  - 10135 Torino, Italy) in 1987 where, from 2001, she is a senior scientist. Her research is focused on: metrology (realization, reproduction, maintenance and dissemination) of vacuum and pressure, extension of primary flowmeter towards low gas flow rate both refereed to vacuum or atmosphere, accurate characterization of geometric elements like capillaries and permeation leaks, used in the quality controls with the primary flow-meters. She is head of the research line "vacuum and pressure metrology" of the Mechanics Division of INRIM and responsible for the Italian National Standard of vacuum and pressure. She has co-authored about one hundred scientific papers and acts as referee for some international journals.

Title and abstract of invited lecture:

Leak rate measurements: from metrological laboratory to industry

In the semiconductor industry, vacuum, nuclear and aerospace technology reliable tightness measurements of the materials and components play a fundamental role on the performance and quality of products. Very small gas flows have to be measured in the field of environmental protection and personal safety. Depending on the requirement, small gas flows have to be delivered either with reference to vacuum (i.e. practically zero pressure) or to atmosphere (ambient pressure). Various types of leak artifacts are available as secondary standards: capillary-leaks, sintered metal-type leak with external gas supply or with rechargeable gas reservoirs. Such artifacts are calibrated against primary flow-meters to assure the correct traceability of the measurements performed.
An overview on different primary flow-meters designed and realized in several National Metrology Institutes for throughput measurements with reference to vacuum and with outlet to atmospheric pressure will be given. The standard flow-meters are essentially based on constant pressure-variable volume method. Other type of primary method consists in measuring the concentration rise of the tracer gas emitted by the leak inside a known volume; to measure the rise of the refrigerant gas concentration infrared techniques are used. The best standard uncertainties of NMIs flow-meters are ranging from 0.6% to 0.8% for molar flow from 1x10-9 mol/s (2.5x10-6 Pa m3/s) to 4 x10-10 mol/s (3.7x10-7 Pa m3/s) and referred to atmospheric pressure. When the gas flow has to be delivered to vacuum the standard uncertainty lies in the range from 1.4% (at 4x10-13 mol/s, 9.7x10-9 Pa m3/s) to 0.14% (at 10-6 mol/s, 1.5x10-4 Pa m3/s).
Today, several methods of leak testing are available that include a variety of technology from a simple to highly sophisticated one. To take a good decision the advantages and the limitations of the various methods must be well known and compared. A discussion on the general leak test requirements will be given together with an analysis of the differences between the available test methods and the proper leak detection technique that has to be chosen. Finally, preliminary theoretical studies on metrological characteristics of the standard leaks are compared with the experimental results.

 

Dr.-Ing. Christian Day

Christian Day studied Process Engineering and received the PhD in Thermodynamics in 1995 at University Karlsruhe. He joined then the Research Centre Karlsruhe (now Karlsruhe Institute of Technology (KIT)) and started to work in the area of customized large vacuum systems. Since 2006, he is head of the Vacuum Department at the Institute of Technical Physics. Under his guidance, the conceptual design of the vacuum systems for the neutrino experiment KATRIN was elaborated as well as the detailed design of the cryopumping systems for the nuclear fusion project ITER. Since 2007, Dr. Day has a teaching position at KIT in vacuum science and technology, Fusion technology, and project management for Engineers. He is member of the Executive Board of the German Vacuum Society since 2008,  leading the vacuum activities in the German Physical Society since 2010 and current co-ordinator for fuelling and vacuum within the European Fusion Programme. In May 2011, he organized a prestigious International Workshop on vacuum gas dynamics. His present research interests are in applications of vacuum gas dynamics for complex geometries by advancing DSMC and developing network-based approaches. Chris Day has contributed as author or co-author to more than 150 journal and conference papers.

Title and abstract of invited lecture:

What Large Vacuum Systems can learn from micro gas flows – and vice versa

The calculation of flows over a wide range of the Knudsen number has seen significant progress in the last decade, much triggered by R&D performed in support of microsystem design and by the increase of computational power. It is known that the deviation from the continuum hypothesis and thermodynamic equilibrium and the dominance of surface and wall effects which appear in microflows result in fluid mechanics which is largely different from the conventional understanding of flows.
However, there are macroscopic systems which work in similar conditions, namely vacuum systems. These systems can be operated to maintain a certain pressure by pumping an incoming process gas flow or be used to pump out a chamber volume; in any case the flow may cover all regimes from viscous to free molecular. There are industrial applications like lithography, semiconductor or coating processes which are mainly operated in the transitional flow regime.
Modern methods of non-equilibrium flow simulation have been used for the design and predictive modeling of a number of vacuum pump types (turbomolecular, drag, scroll), but there are only a few cases up to now where the complete system design has been rigorously based on simulation tools. The design of the vacuum systems of the nuclear fusion project ITER is one of the few examples. However, it has been noted that within industry, it is still not yet sufficiently known, and the traditional approaches with all their limitations, sometimes physically unsound, are still used.
This talk will outline how a vacuum system design can be based on a toolbox of methods encompassing Test Particle Monte Carlo, collisional Monte Carlo (DSMC), kinetic equation, CFD and a network modeler. For code validation, an experimental R&D programme has been launched at Karlsruhe Institute of Technology (KIT) with the aim to parametrically investigate rarefied gas flows through (macrosocpic) ducts at acceptable accuracy over a wide range of Kn. The toolbox as well as the experimental work holds equally well for gas microflows and this lecture aims to bridge the gap between the macro and micro community.

 

Prof. Vladimir V. Aristov

Prof. Vladimir Aristov was educated at Moscow Institute of Physics and Technology (MFTI). He was post-graduate student and received a Ph. D. degree in the same institute. In 1996 he received the Dr. Sci. degree in Dorodnicyn Computing Centre of Russian Academy of Sciences. He is currently the head of the Subdivision of Kinetic Theory of Gases in the Computing Centre. His research is mainly related to the mathematical and physical aspects of describing nonequilibrium flows (including unstable and turbulent) based on the Boltzmann and other kinetic equations. He is the author of numerous publications including a monograph, Direct Methods of Solving the Boltzmann Equation and Study of Nonequilibrium Flows (Kluwer Academic Publishers, 2001).

Title and abstract of invited lecture:

Possibilities of direct methods for solving kinetic equations in the study of microflows

The methods of direct solving the Boltzmann and other kinetic equations have been developed in the last decades. These approaches have some advantages in the study and simulations of microflows, in comparison with popular DSMC methods, un particular, for simulating slow subsonic and unsteady flows as well as for constructing hybrid and parallel algorithms (and  implicit and high order schemes). In the present paper we describe recent results and future possibilities of direct methods of solving kinetic equations for the investigation of a wide circle of problems of rarefied gas dynamics and gas kinetics. The possibilities of UFS (Unified Flow Solver) with the hybrid schemes are overviewed. Steady and unsteady problems for simulating microflows are solved. A special attention is paid to the new effects at the microscale predicted by the kinetic theory which could be useful from the point of view of innovative technologies. These effects related to the nongradient transfer with anomalous transport properties in the nonequilibrium relaxation spatial zones are considered and discussed.

 


 

 

 

 

 

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