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....

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...

Over the past half century, a variety of computational fluid dynamics (CFD) methods and direct simulation Monte Carlo (DSMC) method have been widely successfully applied to gas flows for continuum rarefied regime, respectively. However, they both encounter difficulties when dealing with multiscale in modern engineering problems, where whole system is on macroscopic scale but nonequilibrium effects play an important role. In this paper, we review two particle-based strategies developed flows,...

This paper presents a comprehensive investigation into flow past circular cylinder where compressibility and rarefaction effects play an important role. The study focuses on steady subsonic in the Reynolds-number range 0.1–45. Rarefaction, or non-equilibrium, slip early transition regime are accounted for using method of moments results compared to data from kinetic theory obtained direct simulation Monte Carlo method. Solutions incompressible continuum serve as baseline examine...

In the present study, we investigate flow past a rotating cylinder over wide range of rarefaction from early slip through to free-molecular regime using direct simulation Monte Carlo method. We focus specifically on high-speed conditions and consider Mach numbers near high subsonic, transonic, supersonic regimes. Various parameters such as coefficients lift drag well pressure, skin friction, wall heat transfer have been investigated function both number Knudsen gain insight into physics in...

We numerically study the thin film evaporation process enabled by nanoporous membranes for electronic device cooling. Results show that net evaporative mass flux is determined an interplay between physical effects, quantified Knudsen number, porosity, coefficient, and meniscus shape.

Abstract This paper discusses computational modeling of micro flow in the head–disk interface (HDI) gap using direct simulation Monte Carlo (DSMC) method. Modeling considerations are discussed detail both for a stand‐alone DSMC computation and case hybrid continuum–atomistic that couples Navier–Stokes (NS) equation to solver. The impact number particles cells on accuracy HDI is investigated two‐ three‐dimensional configurations. An appropriate implicit boundary treatment method inflow...

Nonequilibrium heat and mass transfer in a pressure-driven plane Poiseuille flow is investigated using the direct simulation Monte Carlo method from early slip to free molecular regime. Our investigations reveal several nonintuitive, nonequilibrium thermal patterns, including expansion cooling near walls, nonconstant pressure profile, counter-gradient along channel center-line. A bimodal trend tangential flux found transition In upper regime, net entire largely unidirectional opposite...

Understanding ion transport properties from the source to mass spectrometer (MS) is essential for optimizing device performance. Numerical simulation helps in understanding of and, furthermore, facilitates instrument design. In contrast previously reported numerical studies, simulations a continuous injection mode whilst considering realistic space-charge effects have been carried out. The flow field was solved using Reynolds-averaged Navier-Stokes (RANS) equations, and particle-in-cell...

Thin-film evaporation from nanoporous membranes is a promising cooling technology employed for the thermal management of modern electronic devices. We propose an effective one-dimensional analytical approach that can accurately predict temperature and density jump relations, rates, arbitrary membrane configurations. This accomplished through specification coefficient encompasses influence different system parameters, such as porosity, meniscus shape, coefficient, receding height. Our...

Hypersonic hybrid hydrodynamic-molecular gas flow solvers are required to satisfy the two essential requirements of any high-speed reacting code, these being physical accuracy and computational efficiency. The James Weir Fluids Laboratory at University Strathclyde is currently developing an open-source code which will eventually reconcile direct simulation Monte-Carlo method, making use OpenFOAM application called dsmcFoam, newly coded two-temperature fluid dynamics solver named hy2Foam. In...

Understanding ion transport mechanisms in the flow expansion section of first vacuum region a mass spectrometer (MS) with an atmospheric pressure ionization source is essential for optimizing MS sampling interface design. In this study, numerical simulations three types ions two different designs have been carried out. contrast to previously reported studies, nonequilibrium gas dynamics due rarefied effects has considered modeling and realistic space charge effect continuous injection mode....

We present a hybrid multi-scale method that provides capability to capture the disparate scales associated with modelling flow in micro- and nano-devices. Our model extends applicability of an internal-flow by providing framework couple internal (small scale) regions external (large regions. demonstrate application both original methodology new approach field vicinity head-disk interface gap hard disk drive enclosure. The within are modelled extended utilises finite-difference scheme for...

Airflow modeling in the vicinity of head-disk interface (HDI) gap a modern hard disk drive (HDD) enclosure using direct simulation Monte Carlo (DSMC) method is discussed. A hybrid continuum-DSMC model based on Schwarz Alternating employed to couple rarefied flow HDI region which modeled by DSMC continuum outside slider Navier-Stokes equation. The coupling done with aid overlap regions are considered two dimensions and Chapman-Enskog molecular velocity distribution used impose boundary...

Flow past a rotating cylinder has been investigated using the direct simulation Monte Carlo method. The study focuses on occurrence of inverse Magnus effect under subsonic flow conditions. In particular, variations in coefficients lift and drag have as function Knudsen Reynolds numbers. Additionally, temperature sensitivity carried out to assess influence wall computed aerodynamic coefficients. It found that both number significantly affect well onset inversion transition regime.

High-speed rarefied flow past both stationary and rotating cylinders is investigated using the direct simulation Monte Carlo method. Test validations are initially compared against experimental drag coefficients for a cylinder. We then compare various aerodynamic characteristics such as of lift drag, well pressure, skin friction, heat transfer cylinders. The impact speed rarefaction on has also been assessed. In particular, an inverse Magnus effect, which involves change in direction force,...

We implement computer graphics algorithms in the FLASH code to enable compressible high-speed flow simulation past any arbitrary two- and three-dimensional stationary bodies. The body shape is represented a block-structured Cartesian adaptive mesh refinement grid. A high level of required represent accurately also resolve shock features, resulting very large grid sizes for 3D simulations. Simulations are done parallel on IBM Blue Gene/Q computing system which scalability assessed....

A high-order moment method is employed to construct the transport model for non-equilibrium gas flow in micro-scale geometries. The motion of a two-dimensional square micro-cavity solved using 26 equations low Reynolds and Mach number flows early transition regime. computed velocity temperature fields are compared with data obtained from direct simulation Monte Carlo method. It found that able capture phenomena driven micro-cavity, such as counter-gradient heat transfer, which not embedded...

An alternative methodology to compute aerodynamic coefficients, such as lift and drag, using the direct simulation Monte Carlo method is presented. This methodology, which valid for all flow conditions, then applied investigate characteristics of nonequilibrium past a rotating cylinder. work focuses specifically on transition regime in an inverse Magnus effect involving directional change force can be observed. In particular, subsonic are investigated by studying variation coefficients their...

The influence of split-injection on engine performance is studied using system and in-cylinder simulation a two-stroke medium speed diesel engine. System level models for the fuel multi-dimension CFD model combustion chamber were developed calibrated with experimental data. Calibration these from available test data discussed calibration results are presented. SFC NOx predictions show good sensitivity to injection timing variation. These then used simulate split through modification...