Author: John Murray AndersonPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Numerical Simulation of Imperfect Gas Flows
Author: John Murray AndersonNumerical 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 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 Low-speed Gas Flows in Microchannels
Author: C. ChungThe Modeling and Numerical Simulation of Gas Flow Networks
Author: Gabriele EnglPublisher:
ISBN:
Category : Gas dynamics
Languages : en
Pages : 20
Book Description
Abstract: "A network formulation is introduced for the modeling and numerical simulation of complex gas transmission systems like a multi- cylinder internal combustion engine. Several simulation levels are discussed which result in different network representations of a specific system. Basic elements of a network are chambers of finite volume, straight pipes and connections like valves or nozzles. The pipe flow is modeled by the unsteady, one-dimensional Euler equations of gas dynamics. Semi-empirical approaches for the chambers and the connections yield differential-algebraic equations (DAEs) in time. The numerical solution is based on a TVD scheme for the pipe equations and a predictor-corrector method for the DAE-system. Simulation results for an internal combustion engine demonstrate the practical interest of the new approach."
Note on the Importance of Imperfect-gas Effects and Variation of Heat Capacities on the Isentropic Flow of Gases
Author: Coleman duP. DonaldsonPublisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 28
Book Description
Abstract: The errors involved in using the perfect-gas law pv=RT and the assumption of constant heat capacities are evaluated. The basic equations of gas flows taking into account these phenomena separately and at the same time are presented.
Numerical Simulation of the Gas Flow in Semi-detached Close Binary Systems
Author: Numerical Simulation of Compressible Gas Flow Coupled to Heat Conduction in Two Space Dimensions
Author: Daria Y. KorneevaSome Applications of the Numerical Simulation of Gas-phase Flows
Author: Simon Mark WardHypersonic Flows for Reentry Problems
Author: Jean-Antoine DesideriPublisher: Springer
ISBN: 9783540544289
Category : Science
Languages : en
Pages : 268
Book Description
One of the most challenging problems of modern engineering is undoubtedly the prediction of hypersonic flows around space vehicles in reentry conditions. Indeed, the difficulties are numerous: first of all, these flows are very difficult to model, since very complex physical and chemical phenomena take place during the reentry phase; secondly, temperature, velocity and enthalpy are very high and densities are very low, making the reentry process very difficult to reproduce in ground-based experiments. The past three decades have seen important efforts in computational fluid dynam ics relying on the use of supercomputers to simulate these very complicated flows. The numerical simulation based on imperfect models and methods which were es sentially designed for transonic and supersonic flows has still a long way to go in order to be able to predict these hypersonic reentry flows very accurately. This situation has motivated very strong international cooperative efforts with, as the most visible consequences, the EuropelUnited States Short Courses on Hy personics, which were held in Paris, in 1987 [1,2], Colorado Springs in 1989 [3], and Aachen in 1990 [3]. The workshop on Hypersonics whose results are presented and analysed in these volumes is also a direct consequence of this international cooperation. This scien tific event was an initiative of P. Perrier, Head of the Theoretical Aerodynamics Department of DASSAULT AVIATION, who played a key role in the identification of the critical problems and the realisation of experiments, within the Hermes R&D program framework.