Author: C. ChungPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Numerical Simulation of Low-speed Gas Flows in Microchannels
Experimental Study and Numerical Modeling of Gas Flow in Microchannels and Micronozzles
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 110
Book Description
During the course of this research effort gas flows in microchannels and micronozzles were studied both experimentally and numerically. For the experimental study a flow visualization system was built and used to Study gas flows in microscale. Gas velocity measurements in microscope were conducted using both Laser Induced Fluorescence technique in conjunction with Image Correlation Velocimetry and Molecular Tagging Velocimetry technique. For the numerical study three different approaches were utilized. Continuum computational fluid dynamics was first used to study gas flows in microchannels and micronozzles. For micronozzles, effects of geometrical scaling down and different gas propellants were studied. For microchannels, slip versus no-slip boundary condition and compressibility and rarefaction effects were studied. Secondly, Direct simulation Monte Carlo (DSMC) method was used to study low Reynolds number flows in a conical micronozzle. The DSMC simulations were compared with the continuum model and available experimental data, and also used to study propellant gas temperature effect on the generated thrust Thirdly, a Unified Flow Solver that utilizes hybrid approach using deterministic Boltzmann solver for highly non-equilibrium flows at high Knudsen number and continuum solvers for low Knudsen numbers was tested and demonstrated for gas flows in microscale. Tested cases included gas flows in both microchannels and micronozzles.
MEMS
Author: Mohamed Gad-el-HakPublisher: CRC Press
ISBN: 1420036572
Category : Technology & Engineering
Languages : en
Pages : 494
Book Description
Thoroughly revised and updated, the new edition of the best-selling MEMS Handbook is now presented as a three-volume set that offers state-of-the-art coverage of microelectromechanical systems. The first volume, MEMS: Introduction and Fundamentals builds the required background and explores various physical considerations of MEMS. Topics include scaling, simulation models, the basics of control theory, and the physics of materials flow, thin liquid films, and bubble/drop transport. New chapters in this edition address lattice Boltzmann simulations and microscale hydrodynamics. Standing well on its own, this books builds an outstanding foundation for further exploration of MEMS and their applications.
Numerical Simulation of Rarefied Gas Flow in Micro and Vacuum Devices
Author: Anirudh Singh RanaPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
It is well established that non-equilibrium flows cannot properly be described by traditional hydrodynamics, namely, the Navier-Stokes-Fourier (NSF) equations. Such flows occur, for example, in micro-electro-mechanical systems (MEMS), and ultra vacuum systems, where the dimensions of the devices are comparable to the mean free path of a gas molecule. Therefore, the study of non-equilibrium effects in gas flows is extremely important. The general interest of the present study is to explore boundary value problems for moderately rarefied gas flows, with an emphasis on numerical solutions of the regularized 13--moment equations (R13). Boundary conditions for the moment equations are derived based on either phenomenological principles or on microscopic gas-surface scattering models, e.g., Maxwell's accommodation model and the isotropic scattering model.Using asymptotic analysis, several non-linear terms in the R13 equations are transformed into algebraic terms. The reduced equations allow us to obtain numerical solutions for multidimensional boundary value problems, with the same set of boundary conditions for the linearized and fully non-linear equations. Some basic flow configurations are employed to investigate steady and unsteady rarefaction effects in rarefied gas flows, namely, planar and cylindrical Couette flow, stationary heat transfer between two plates, unsteady and oscillatory Couette flow. A comparison with the corresponding results obtained previously by the DSMC method is performed. The influence of rarefaction effects in the lid driven cavity problem is investigated. Solutions obtained from several macroscopic models, in particular the classical NSF equations with jump and slip boundary conditions, and the R13--moment equations are compared. The R13 results compare well with those obtained from more costly solvers for rarefied gas dynamics, such as the Direct Simulation Monte Carlo (DSMC) method. Flow and heat transfer in a bottom heated square cavity in a moderately rarefied gas are investigated using the R13 and NSF equations. The results obtained are compared with those from the DSMC method with emphasis on understanding thermal flow characteristics from the slip flow to the early transition regime. The R13 theory gives satisfying results including flow patterns in fair agreement with DSMC in the transition regime, which the conventional Navier-Stokes-Fourier equations are not able to capture.
Numerical Simulation of Gas-liquid Bubbly Flows
Author: Bernard BunnerNumerical Simulation of the Gas Flow in Semi-detached Close Binary Systems
Author: Numerical Simulation of Imperfect Gas Flows
Author: John Murray AndersonAdvances in Multiphysics Simulation and Experimental Testing of MEMS
Author: Attilio FrangiPublisher: World Scientific
ISBN: 1860948626
Category : Science
Languages : en
Pages : 504
Book Description
This volume takes a much needed multiphysical approach to the numerical and experimental evaluation of the mechanical properties of MEMS and NEMS. The contributed chapters present many of the most recent developments in fields ranging from microfluids and damping to structural analysis, topology optimization and nanoscale simulations. The book responds to a growing need emerging in academia and industry to merge different areas of expertise towards a unified design and analysis of MEMS and NEMS.
Numerical Simulation of Rarefied Gas Flows Based on the Kinetic Approach
Author: Alexey PolikarpovPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
This work is devoted to the development of the numerical resolution of the kinetic model equations such as BGK, S-model, ES-model by the discrete velocity method. The different approximations of the Boltzmann equation are presented.
Numerical Simulation of the Gas Flow in Semi-detached Close Binary Systems
Author: Ronald Everett TaamPublisher:
ISBN:
Category : Eclipsing binaries
Languages : en
Pages : 178
Book Description