Direct Monte Carlo simulation

Since the middle of the 1990s, another computation method, direct simulation Monte Carlo (DSMC), has been employed in analysis of ultra-thin film gas lubrication problems [13-15]. DSMC is a particle-based simulation scheme suitable to treat rarefied gas flow problems. It was introduced by Bird [16] in the 1970s. It has been proven that a DSMC solution is an equivalent solution of the Boltzmann equation, and the method has been effectively used to solve gas flow problems in aerospace engineering. However, a disadvantageous feature of DSMC is heavy time consumption in computing, compared with the approach by solving the slip-flow or F-K models. This limits its application to two- or three-dimensional gas flow problems in microscale. In the... 

Zhang, Y. R. and Meng,Y. G., Direct Simulation Monte Carlo [32] Method on Nanoscale Effect of Gas Mean Free Path," Lubr. 

Sun, H., Faghri, M., Effect of surface roughness on nitrogen flow in a micro-channel using the Direct Simulation Monte Carlo Method (DSMC), Numerical Heat Transfer A 43 (2003) 1-8. 

DSMC Direct simulation Monte Carlo method... 

Understanding the dependence of film structure and morphology on system layout and process parameters is a core topic for the further development of ZnO technology. Work is being performed on in situ characterization of deposition processes. Growth processes are simulated using Direct Simulation Monte-Carlo (DSMC) techniques to simulate the gas flow and sputter kinetics simulation and Particle-ln-Cell Monte-Carlo (PICMC) techniques for the plasma simulation [132]. 

Under high vacuum conditions, i.e., pressure p < 10 2 mbar, the material transfer can be described using Monte Carlo simulations. Usually, inelastic collisions and collective phenomena as shock waves cannot be considered here. The so called Direct Simulation Monte Carlo method allows extension to slightly higher gas pressures. 

In Chap. 2, Raz and Levine investigate a regime of dynamics where the motion along intermolecular coordinates is comparable or faster than that of intramolecular vibrational modes. These conditions exist momentarily when a large cluster impacts a surface at hyperthermal velocities ( 10 kms ). In Chap. 3, Boyd describes the challenges facing a direct simulation Monte Carlo modeler of hypersonic flows in a regime intermediate to the continuum and free molecular flow limits. Many of the lessons... 

Modified Navier-Stokes equations are also used by [10] in the range of 0.01 < Kn < 30 and the results are eompared to Direct Simulation Monte Carlo (DSMC) and linearized Boltzman solutions. They obtained good results for the centerline velocity, assuming b = -1, but deviations for the slip veloeity for 0.1 < Kn < 5. 

The Boltzmann equation is solved by the particulate methods, the Molecular Dynamics (MD), the Direct Simulation Monte Carlo (DSMC) method, or by deriving higher order fluid dynamics approximations beyond Navier-Stokes, which are the Burnett Equations. The Burnett equation... 

In the free-molecular flow regime, the molecular mean free path is of the same order as the channel characteristic length. Because Newton s 2" Law should more or less be applied to each molecule, the analysis becomes extremely tedious and complicated. The current computational tools, the Molecular Dynamics (MD) and the Direct Simulation Monte Carlo, are still incapable of providing effective and efficient solutions. 

Figure4.6 Left a microfluidicftlterexample.The baths are simulated by using the continuum Stokes equations and the filter is simulated by using the direct simulation Monte Carlo (DSMC) method. Right plot of temperature in the device...

Kruis, E. E., Maisels, A. Eissan, H. 2000 Direct simulation Monte Carlo method for particle coagulation and aggregation. AIChE Journal 46,1735-1742. 

Liffman, K. 1992 A direct simulation Monte-Carlo method for cluster coagulation. Journal of Computational Physics 100, 116-127. 

Maisels, A., Kruis, F. E. Fissan, H. 2004b Direct simulation Monte Carlo for simultaneous nucleation, coagulation, and surface growth in dispersed systems. Chemical Engineering Science 59, 2231-2239. 

The plume development in MD simulations can only be followed up to a few nanoseconds after the pulse, which is not enough to compare the data with various experimental techniques (such as MALDI, TOF-MS, shadowgra-phy, interferometry, or for PLD). The long-term plume expansion is then modeled by the direct simulation Monte Carlo method, which was recently applied to systems relevant to MALDI [112]. 

One of the earliest particle-based schemes is the Direct Simulation Monte Carlo (DSMC) method of Bird [126]. In DSMC simulations, particle positions and velocities are continuous variables. The system is divided into cells and pairs of particles in a cell are chosen for collision at times that are determined from a suitable distribution. This method has seen wide use, especially in the rarefied gas dynamics community where complex fluid flows can be simulated. 

Diffusive flow for neutrals The importance of convective vs. diffusive flow of neutrals is determined by the Peclet number Pe = uL/D, where L is a characteristic dimension of the system. Away from inlet and exit ports, the characteristic length will be on the order of the reactor dimension. The system will be primarily diffusive when Pe 1. For CI2 gas in a reactor with L 0.1 m and a neutral species diffusivity of D 5m s at 20mtorr, the Peclet number will be Pe 1 when M = 50ms. Convective gas velocities are not likely to be that high, except for a small region near the gas inlet ports. It follows that gas flow can be approximated as diffusive this obviates the need for solving the full Navier-Stokes equations which adds to the computational burden. It should be noted that both the diffusivity and the convective velocity scale inversely with gas pressure, so the Pe number is independent of pressure. However, as the pressure is lowered to the point of free molecular flow, the gas diffusion coefficient has no meaning any more. Direct Simulation Monte Carlo (DSMC) [41, 143] can then be applied to solve for the fluid velocity profiles. 

DSMC Direct simulation Monte Carlo IP Information preservation Kn Knudsen number NS Navier-Stokes... 

Direct simulation Monte Carlo (DSMC) method is a statistical approach widely employed for simulating rarefied micro-/nanoflows. DSMC is... 

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