Discrete velocity modelling of gaseous mixture flows in MEMS (original) (raw)
Physics of Fluids, 2005
The flow of binary gaseous mixtures through rectangular microchannels due to small pressure, temperature, and molar concentration gradients over the whole range of the Knudsen number is studied. The solution is based on a mesoscale approach, formally described by two coupled kinetic equations, subject to diffuse scattering boundary conditions. The model proposed by McCormack substitutes the complicated collision term and the resulting kinetic equations are solved by an accelerated version of the discrete velocity method. Typical results are presented for the flow rates and the heat fluxes of two different binary mixtures ͑Ne-Ar and He-Xe͒ with various molar concentrations, in two-dimensional microchannels of different aspect ͑height to width͒ ratios. The formulation is very efficient and can be used instead of the classical method of solving the Navier-Stokes equations with slip boundary conditions, which is restricted by the hydrodynamic regime. Moreover, the present formulation is a good alternative to the direct simulation Monte Carlo method, which often becomes computationally inefficient.
Microchannel Fluid Flow and Heat Transfer By Lattice Boltzmann Method
2014
Micro flow has become a popular field of interest due to the advent of micro electromechanical systems (MEMS). In this work, the lattice Boltzmann method, a particle-based approach, is applied to simulate the two-dimensional micro channel fluid flow. We simulated fluid flow and heat transfer inside microchannel, the prototype application of this study is micro-heat exchangers. The main incentive to look at fluidic behaviour at micron scale is that micro devices tend to behave much differently from the objects we are used to handling in daily life. The choice of using LBM for micro flow simulation is a good one owing to the fact that it is based on the Boltzmann equation which is valid for the whole range of the Knudsen number. Slip velocity and temperature jump boundary conditions are used for the microchannel simulations with Knudsen number values covering the slip flow. The lattice Bhatnagar-Gross-Krook single relaxation time approximation was used. The results found are compared ...
2001
Interest in microelectromechanical systems (MEMS) has experienced explosive growth during the past few years. Such small devices typically have characteristic size ranging from 1 mm down to 1 micron, and may include sensors, actuators, motors, pumps, turbines, gears, ducts and valves. Microdevices often involve mass, momentum and energy transport. Modeling gas and liquid flows through MEMS may necessitate including slip,
A Parallel Thermal Lattice Boltzmann Model with Flux Limiters for Microscale Flow
International Journal of Modern Physics C, 2008
We propose a thermal lattice Boltzmann model to study gaseous flow in microcavities. The model relies on the use of a finite difference scheme to solve the set of evolution equations. By adopting diffuse reflection boundary conditions to deal with flows in the slip regime, we study the micro-Couette flow in order to select the best numerical scheme in terms of accuracy. The scheme based on flux limiters is then used to simulate a micro-lid-driven cavity flow by using an efficient and parallel implementation. The numerical results are in very good agreement with the available results recovered with different methods.
MDPI eBooks, 2019
France. He initiated and co-chaired a series of French (Flu'02 to Flu'06) and European (Flu'08 to Flu'18) Microfluidics Conferences. His current research is mainly focused on gas microflows, with a particular interest in the experimental analysis of rarefied flows. He was the coordinator of the GASMEMS European Network aimed at training young researchers in the field of gas flows in MEMS. He is the author of more than 140 scientific papers in international journals or conferences and the editor or co-author of four textbooks.
Numerical simulations of micro-channel devices with Lattice Boltzmann method
31ST INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS: RGD31, 2019
The study is devoted to the application of Lattice Boltzmann Method (LBM) and the Unified Gas-Kinetic Scheme (UGKS) to the numerical simulations of micro-channel flows in transitional regime. Both methods present the variants of the meso-scale gas-dynamic approach. This way of mathematial modelling allows taking into account both micro-and macro-scale process of a flow. At the same time, UGKS saves much more physics from the micro-scale molecular interaction mechanism than LBM. It leads to much more demands in sense of numerical resources. The numerical results are presented for the Knudsen compressor flow.
Journal of Statistical Physics, 2015
In this study, gaseous flow through a micro/nano-channel is investigated via a novel two relaxation time lattice Boltzmann method. In this method, the slip velocity at the fluidsolid interface is realized by defining the free relaxation parameter. Furthermore, in order to capture the non-linear phenomena associated with the Knudsen layer, the wall function correction is employed. To this respect, different available wall functions are implemented. The objective of the study is to provide a comparative study on the accuracy, range of applicability and computational efficiency of these wall functions in a wide range of Knudsen numbers. The results of the present study are compared against direct simulation Mont Carlo and information preservation data. It is found that only a few of the implemented wall functions are capable of predicting the flow behavior with reasonable accuracy, particularly when the Knudsen number lies in the transition flow regime.