Assam, A and Kalkote, Nikhil Narayan and Dongari, Nishanth and Eswaran, Vinayak
(2017)
Computation of Rarefied Gas Flows in Nano/micro Devices using an Indigeneous Developed Computational Fluid Dynamics Solver.
In: Proceedings of the International Conference on Nanotechnology, Ideas, Innovations & Initiatives (ICN:3I),, 68 December 2017, IIT Roorkee, India.
Full text not available from this repository.
(
Request a copy)
Abstract
Gaseous Nano/micro Electronic Mechanical Systems (NEMS/MEMS) are used for measurement and control in the atomic level. Numerical simulation of such system is important for understanding the gas flow behaviour in such devices. Nonequilibrium effects such as small characteristic length, rarefaction and gassurface interactions characterize such flow behaviour. The Knudsen number, Kn, ratio of the molecular mean free path, λ, to the characteristic length of the geometry, l is used to characterize the translational nonequilibrium of a rarefied gas flow in nano/micro devices. For high gas density with small Kn (Kn≤0.001) the conventional NavierStokes (NS) equations are applicable. When the gas density becomes small, the mean free path of gas becomes large and the nonequilibrium effects appear in the flow with fewer collisions between molecules. The conventional NavierStokes equation with velocity slip and temperature jump conditions can be used to simulate the slipflow regime 0.001≤ Kn ≤ 0.1. The only other method for such flows, direct simulation Monte Carlo (DSMC), is computationally quite expensive, especially for threedimensional flows. In this work we demonstrate the functionality of our allspeed threedimensional indigenously developed unstructured grid cellbased finitevolume computational fluid dynamics (CFD) solver for MEMS/NEMS devices. The solver is well validated for relatively high gas density flows corresponding to small Kn (Kn≤0.001). The meanflow in NS equation is solved using lowspeed preconditioning with ROE flux in a density based solver. The timestepping has been done implicitly using the LUSGS scheme. The Maxwell velocity slip and Smoluchowski temperature jump boundary condition is used at the wall. The Sutherland Law of viscosity is used for the gases considered in this study, i.e. nitrogen and argon. In the final paper, we will present the results for gaseous flow in (NEMS/MEMS) devices such as pressure driven micro/nano channel and cavity. Three cases will be considered (a) pressure driven 90degree bent microchannel, (b) liddriven microcavity and (c) pressure driven backward facing step nanochannel. The results will be compared with available experimental, DSMC and other CFD data.
[error in script]
Actions (login required)

View Item 