Showing papers by "Anthony G. Straatman published in 2003"
TL;DR: In this paper, the effect of boundary layer thickness on vortex shedding from a square cylinder in proximity to a solid wall is examined. But the results show that, in general, thickening of the wall boundary layer causes wake periodicity to persist for increasingly smaller cylinder-to-wall gap widths, S/D.
19 citations
TL;DR: In this paper, the flow inside channels with periodic, wavy walls of arbitrary shape is considered numerically and solutions are obtained using either a perturbation approach, for weak modulation amplitude, or a finite volume technique, for strong amplitude.
Abstract: The flow inside channels with periodic, wavy walls of arbitrary shape is considered numerically. Solutions are obtained using either a perturbation approach, for weak modulation amplitude, or a finite volume technique, for strong amplitude. The flow is examined for sinusoidal, arched and triangular modulation over a wide range of amplitude, wavelength and Reynolds number in the steady laminar regime. For weak wall modulation (e<0.3, α<2, where e and α are the dimensionless half-wave height and wavelength, respectively), it is found that the flow behavior along the modulated wall is of the boundary-layer type. As such, the critical Reynolds number, Rec, for separation for each modulation shape can be expressed as an explicit function of e and α, while the location of separation and pressure distribution along the modulated wall scale with e, α, and Rec. For strong modulations, the boundary layer model is no longer satisfactory to predict the flow behavior and deviations from the trends found for weaker mod...
17 citations
TL;DR: In this paper, a periodic boundary condition was developed that can be used in conjunction with a specified flow rate to produce accurate results in spatially periodic geometries, where the flow rate is imposed at the inlet in terms of a bulk velocity.
Abstract: A periodic boundary condition has been developed that can be used in conjunction with a specified flow rate to produce accurate results in spatially periodic geometries. This condition is useful in situations where the flow rate is known, or more importantly, in cases where the pressure gradient is not known a priori, such as in countercurrent flows. Using the present condition, the flow rate is imposed at the inlet in terms of a bulk velocity, but the velocity field evolves as part of the solution. The condition is formulated to be suitable for both fixed and moving periodic domains. For the case of a moving domain, a correction is introduced to account for changes in the instantaneous velocity through the periodic edges. Under periodic conditions, these corrections integrate to zero over a complete (temporal) period. The new periodic condition is shown to produce accurate results for flat and wavy-walled channels under both induced flow and countercurrent conditions. Copyright © 2003 John Wiley & Sons, Ltd.
7 citations