Classical continuummethods break down for rarefied gas flows inmicro-channels. Twononcontinuumhydrodynamicmodels are investigated here: compressible Korteweg fluid-like andBiVelocity (VolumeDiffusion) hydrodynamicmodels. The pressure driven rarefied gasflow in a rectangularmicro-channel in thewhole range of Knudsen number is numerically considered. The Kortewegmodel shows improved results in co...

Classical continuummethods break down for rarefied gas flows inmicro-channels. Twononcontinuumhydrodynamicmodels are investigated here: compressible Korteweg fluid-like andBiVelocity (VolumeDiffusion) hydrodynamicmodels. The pressure driven rarefied gasflow in a rectangularmicro-channel in thewhole range of Knudsen number is numerically considered. The Kortewegmodel shows improved results in co...

A recently established version of the discrete-ordinates method is used to develop a solution to a class of problems in the theory of rarefied-gas dynamics. In particular, an accurate solution for the flow, described by the Bhatnagar, Gross and Krook model, of a rarefied gas between two parallel plates is developed for a wide range of the Knudsen number.

The cylindrical Couette flow of a rarefied gas is investigated, under the diffuse-specular reflection condition of Maxwell's type on the cylinders, in the case where the inner cylinder is rotating whereas the outer cylinder is at rest. The inverted velocity profile for small accommodation coefficients, pointed out by Tibbs, Baras, and Garcia [Phys. Rev. E 56, 2282 (1997)] on the basis of a Mont...

Both the particle based Direct Simulation Monte Carlo (DSMC) method and a compressible Navier-Stokes based continuum method are used to investigate the flow inside micronozzles and to predict the performance of such devices. For the Navier-Stokes approach, both slip and no-slip boundary conditions are applied. Moreover, the two methods have been coupled to be used together in a hybrid particle-...

Maxwell’s original slip boundary condition is widely misapplied in current rarefied gas flow calculations (e.g. in hypersonics, microfluidics). If its commonly-accepted form is applied in simulations of gas flows over curved or moving surfaces, crucial physics can be lost. We give examples of such cases. We also propose a new higher-order boundary condition which is based on Maxwell’s original ...

An analytical version of the discrete-ordinates method (the ADO method) is used to establish concise and particularly accurate solutions to the problem of sound-wave propagation in a rarefied gas. The analysis and the numerical work are based on a rigorous form of the linearized Boltzmann equation (for rigid-sphere interactions), and in contrast to many other works formulated (for an infinite m...

The present lecture is devoted to experimental and theoretical modelling for rarefied aerodynamics. General features of experimental studies in rarefied flows are discussed. Experimental facilities designed in Saint Petersburg State University for rarefied aerodynamics and plasma flow control are described. Several theoretical models for non-equilibrium reacting flows in the slip regime are pre...

The hypersonic rarefied wind tunnel has lately been developed at JAXA. The characteristics of hypersonic rarefied flows have been investigated experimentally and numerically in this work. Using a sphere pendulous model, the test flow has been probed by measuring its displacement due to the aerodynamic force. In addition, a spatial variation of total pressure of the test flow has also been measu...

A hybrid particle scheme is presented for the simulation of compressible gas flows involving both continuum regions and rarefied regions with strong translational nonequilibrium. The direct simulation Monte Carlo (DSMC) method is applied in rarefied regions, while remaining portions of the flowfield are simulated using a DSMC-based low diffusion particle method for inviscid flow simulation. The...