Flow instability and turbulent transition can be well explained using a new proposed theory--Energy gradient theory [1]. In this theory, the stability of a flow depends on the relative magnitude of energy gradient in streamwise direction and that in transverse direction, if there is no work input. In this note, it is shown based on the energy gradient theory that inviscid nonuniform flow is uns...

The influence of the inlet swirl velocity profile shape on the decay of swirl in steady-state, incompressible, laminar pipe flows is investigated by means of computational fluid dynamics. The investigation is carried out for a Reynolds number of 2000, which marks the upper limit of the laminar flow behavior for unidirectional pipe flow. Computations are performed for two different mean swirl nu...

Abstract. In this paper, a Cascaded Lattice Boltzmann Method with second order slip boundary conditions is developed to study gas flows in a microchannel in the slip and transition flow regimes with a wide range of Knudsen numbers. For the first time the effect of wall confinement is considered on the effective mean free path of the gas molecules using a function with nonconstant Bosanquet para...

Stress waves contain useful information about the properties of porous materials; they can be recovered through different non-destructive testing methods such as crosswell, vertical seismic profile, borehole logging as well as sonic tests. In all these methods, it is crucial to assess the effects of frequency on wave attributes including velocity and intrinsic attenuation. The dependency of per...