dsmcFoam+ is a direct simulation Monte Carlo (DSMC) solver for rarefied gas dynamics, implemented within the OpenFOAM software framework, and parallelised with MPI. It open-source released under GNU General Public License in publicly available repository that includes detailed documentation tutorial DSMC flow cases. This release of code many features not found standard dsmcFoam, such as molecular vibrational electronic energy modes, chemical reactions, subsonic pressure boundary conditions....

Maxwell's famous slip boundary condition is often misapplied in current rarefied gas flow calculations (e.g., hypersonics, microfluidics). For simulations of flows over curved or moving surfaces, this means crucial physics can be lost. We give examples such cases. also propose a higher-order based on general equation and the constitutive relations derived by Burnett. Unlike many other conditions these are applicable to any form surface geometry. It shown that "Maxwell-Burnett" reasonable...

The method of moments is employed to extend the validity continuum-hydrodynamic models into transition-flow regime. An evaluation regularized 13 moment equations for two confined flow problems, planar Couette and Poiseuille flows, indicates some important limitations. For at a Knudsen number 0.25, they fail reproduce Knudsen-layer velocity profile observed using direct simulation Monte Carlo approach, higher-order are not captured particularly well. Moreover, flow, this system creates large...

For gas flows in microchannels, slip motion at the solid surface can occur even if Mach number is negligibly small. Since Knudsen of flow a long microchannel vary widely and Navier-Stokes equations are not valid for numbers beyond 0.1, an alternative method that be applicable to continuum, transition regimes highly desirable. The lattice Boltzmann equation (LBE) approach has recently been expected have such potential. However, some hurdles need overcome before it applied simulate rarefied...

It has long been recognized that the fluid mechanics of gas-phase microflows can differ significantly from macroscopic world. Non-equilibrium effects such as rarefaction and gas-surface interactions need to be taken into account, it is well known no-slip boundary condition Navier-Stokes equations no longer valid. Following ideas proposed by Maxwell, generally accepted extended slip-flow regime, provided Knudsen number less than 10− 1. Improvements in micro-fabrication techniques, however,...

Ultrasound standing wave radiation force and laminar flow have been used to transfer yeast cells from one liquid medium another (washing) by a continuous field-flow fractionation (FFF) approach. Two co-flowing streams, cell-free suspending phase (flow rate > 50% of the total flow-through volume) suspension, were introduced parallel nodal plane 3 MHz resonator. The resonator was fabricated single pressure at centre line chamber. Laminar ensured stable interface maintained as two phases flowed...

The relationship governing the optimum ratio between diameters of parent and daughter branches in vascular systems was first discovered by Murray using principle minimum work. This is now known as Murray's law states that cube diameter vessel must equal sum cubes vessels. For symmetric bifurcations, an important consequence this geometric rule tangential shear stress at wall remains constant throughout network. In present paper, we extend hydrodynamic concept to arbitrary cross-sections...

In recent years, lattice Boltzmann methods have been increasingly used to simulate rarefied gas flows in microscale and nanoscale devices. This is partly due the fact that method computationally efficient, particularly when compared solution techniques such as direct simulation Monte Carlo approach. However, models developed for difficulty capturing nonlinear relationship between shear stress strain rate within Knudsen layer. As a consequence, these are equivalent slip-flow solutions of...

Gaseous flow and heat transfer in a lid-driven cavity under nonequilibrium conditions is investigated using the direct simulation Monte Carlo method, from slip to free-molecular regime. The emphasis on understanding thermal features. impact of lid velocity various degrees rarefaction shear stress flux rates are analyzed. role expansion cooling viscous dissipation mechanism investigated. Complex phenomena, such as counter-gradient transfer, revealed by simulations which conventional...

The problem of redistributing the work load on parallel computers is considered. An optimal redistribution algorithm, which minimises Euclidean norm migrating load, derived. relationship between this algorithm and some existing algorithms discussed convergence new studied. Finally, numerical results randomly generated graphs as well related to real meshes are given demonstrate effectiveness algorithm. © 1998 John Wiley & Sons, Ltd.

The velocity slip on the solid surfaces of microscale cylindrical Couette flow is investigated using Langmuir adsorption model for gas-surface molecular interaction. accommodation coefficient in Maxwell model, which a free parameter based concept diffusive reflection, replaced by physical heat model. phenomenon inversion then clearly explained introducing polar hodograph plane. It also shown that quantity used to determine momentum concentric geometry should be upon angular velocity, not...

Due to its computational efficiency, the kinetic-based lattice Boltzmann method has recently been used model nonequilibrium gas dynamics. With appropriate boundary conditions, models have able capture both velocity slip and temperature jump at a solid surface. To enable these simulate flows in transition regime, high-order modified proposed. In this paper, we demonstrate advantages of standard Bhatnagar-Gross-Krook predicting rarefaction phenomenon. addition, show that current are not yet...

Due to its intrinsically kinetic nature, lattice Boltzmann (LB) approach simulating non-equilibrium gas flows has recently attracted significant research interest. Compared with other methods, it can offer a significantly smaller computational cost. To capture the nonlinear high-order rarefaction phenomena in flows, geometry-dependent local mean free path been proposed be implemented our "high-order" LB model. A series of tests on effects and Knudsen layer interference have carried out...

A new Direct Numerical Simulation (DNS) code HAMISH with Adaptive Mesh Refinement (AMR) has been developed to simulate compressible reacting flow in a computationally economical manner. The focus is on problems where high gradients of temperature, density and species mass fraction remain localised, for example within the interior structure flames. resolution requirements such local high-gradient regions often determine global mesh spacing when uniform meshes are used. numerical framework...