We explore two low-dimensional dynamical systems modeling transition to turbulence in shear flows to try to understand the nature of the boundary ∂B of the basin of attraction B of the stable, laminar point at the origin of coordinates. Components of ∂B are found to exist in two types: one (the ’strong’ type) separating B from a complementary set where orbits never relaminarize, and a second (t...

An experimental study is conducted to determine local heat-transfer performance and mechanisms in radial flow through two parallel heated disks. Three distinct heat-transfer mechanisms are disclosed along the flow passage: steady laminar, periodic laminar, and turbulent. The heat-transfer performance is enhanced proportional to the 0.5 and 0.8 powers of Reynolds number, in the steady periodic a...

Laminar and turbulent pipe flow of a ferrofluid with an imposed linearly polarized, oscillating, magnetic field is examined here. Experimental results show a fractional pressure drop dependence on flow rate, magnetic field strength, and oscillation frequency. Calculations are presented, which show that ferrofluid theory can explain the flow phenomena in laminar and turbulent pipe flow. The mode...

To simulate the effect of free st ream turbulence on turbulent spot formation, experiments were conducted on the interaction of localized three-dimensional disturbances with the harmonic waves in a laminar boundary layer on a flat plate. Experiments conducted in three-dimensional diverging flow (but zero pressure gradient) show, while individually the disturbances decay downstream, their intera...

Title Numerical visualization of boundary layer transition when negative Magnus effect occurs Author(s) Muto, Masaya; Tsubokura, Makoto; Oshima, Nobuyuki Citation Journal of Visualization, 15(3): 261-268 Issue Date 2012-08 DOI Doc URL http://hdl.handle.net/2115/53053 Right The original publication is available at www.springerlink.com Type article (author version) Additional Information File Inf...

To reveal the inner mechanism of gas explosion dynamic behavior affected by gas equivalent concentration, a high speed Schlieren image system and flow field measurement technology was applied to record the gas explosion flame propagation and flame structure transition. The results show that a flame front structure transition occurs, followed by a flame accelerating propagation process. The lami...

The turbulent potential model is a RANS model that avoids modeling the Reynolds stress tensor. As a result it has the ability to obtain the physical accuracy of Reynolds stress transport equation models at a cost and complexity comparable to popular two equation models. The model’s ability to predict channel flow, free-shear layers, homogeneous shear flow, stagnation point flow, backward facing...

A new universal theory for flow instability and turbulent transition is proposed in this study. Flow instability and turbulence transition have been challenging subjects for fluid dynamics for a century. The critical condition of turbulent transition from theory and experiments differs largely from each other for Poiseuille flows. This enigma has not been clarified so far owing to the difficult...

The performance of a generic surfboard fin is investigated in a cavitation tunnel to gain basic understanding of the viscous flows involved for future systematic experimental and computational studies. Measurements of lift and drag forces, pitching moment and results of flow visualisation are presented. Surface flow visualisation studies reveal relatively complex boundary layer transition and s...