Journal ArticleDOI
Kinetic theory of the drag force on objects in rarefied gas flows
TLDR
In this paper, a kinetic theory is presented for the drag force on objects in rarefied gas flows as a function of the inverse Knudsen number, and it is shown how the coefficients of this expansion are related to various sequences of collisions among the gas molecules and the object.Abstract:
A kinetic theory is presented for the drag force on objects in rarefied gas flows as a function of the inverse Knudsen number. It is demonstrated that an expansion of the drag force around the free molecular limit contains terms that depend logarithmically on the inverse Knudsen number. It is shown how the coefficients of this expansion are related to various sequences of collisions among the gas molecules and the object. The analogy between the inverse Knudsen number expansion for the drag force on objects in rarefied gases and the density expansion of the transport properties of moderately dense gases is elucidated.read more
Citations
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Journal ArticleDOI
Unifying kinetic approach to phoretic forces and torques onto moving and rotating convex particles
Martin Kröger,Markus Hütter +1 more
TL;DR: An accommodation coefficient is implemented characterizing the collision process in order to derive the tracer particle's complete equations of motion in a form which offers the possibility for immediate numerical implementation, and the analytical exploration of the effect of particle shape and size on phoretic drift velocity.
Journal ArticleDOI
Kinetic theory of drag on objects in nearly free molecular flow
TL;DR: In this article, the first correction term to the free-molecular drag limit was derived using an analogy between the density expansion of the transport coefficients of moderately dense gases and the inverse-Knudsen-number expansion of drag on objects in nearly free molecular flows.
Journal ArticleDOI
Analysis of Standby Losses and Charging Cycles in Flywheel Energy Storage Systems
TL;DR: In this paper, the authors provide a loss assessment methodology for flywheel windage losses and bearing friction losses using the latest available information, and the effect of the number of charging cycles on the relative importance of flywheel standby losses has also been investigated and the total losses and efficiency have been calculated accordingly.
Journal ArticleDOI
Effects of Drag Force of Helium Gas on a Spinning Superconducting Rotor
TL;DR: The results show that the angular velocity is decaying with exponential function when the rotor rotates in the gas, and rotor deceleration at different gas pressures with different analysis methods is necessary.
Journal ArticleDOI
Nanoscale Fluid Flow Over Two Side-by-Side Cylinders With Atomically Rough Surface
TL;DR: In this paper, a molecular dynamics simulation of flow over two side-by-side cylinders with atomically rough surfaces is presented, where the surface roughness is constructed by external protrusion of atoms on the surface of the cylinders with specified amplitude and width.
References
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Book
Rarefied Gas Dynamics
TL;DR: In this paper, the authors present a simulation of a free jet expansion of a high-energy scattering of molecular beams in the presence of high-temperature Viscosity cross sections.
Journal ArticleDOI
Theory and Application of the Boltzmann Equation
Carlo Cercignani,A. S. Berman +1 more
Journal Article
Monte-carlo simulation in an engineering context
TL;DR: It is shown that requirements for the accurate modeling of engineering flows are best met by a new molecular model called the variable hard sphere, or VHS, model, and the necessary kinetic theory for the application of this model is presented.
Journal ArticleDOI
Hard-sphere dynamics and binary-collision operators
TL;DR: In this paper, the binary-collision expansion for potentials consisting of a hard core and a soft tail is discussed and the restrictions to their applicability are determined, and the different expressions so far proposed are critically examined.
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