The energy gradient theory has been proposed with the aim of better understanding the mechanism of flow transition from laminar flow to turbulent flow. In this theory, it is suggested that the transition to turbulence depends on the relative magnitudes of the energy gradient amplifying the disturbance and the viscous friction damping that disturbance. For a given flow geometry and fluid propert...

We present stability analyses for the boundary-layer flow over broad cones (half-angle ψ > 40◦) rotating in imposed axial flows. Preliminary convective instability analyses are presented that are based on the Orr–Sommerfeld equation for a variety of axial-flow speeds. The results are discussed in terms of the limited existing experimental data and previous stability analyses on related bodies. ...

The purpose of this contribution is to present some examples for the use of recent data processing and visualization techniques for the study of unsteady vortical flows. The basic idea is to extract vortices, shear layers and data defining their current state from DNS data and to track their evolution in time. Some apparent signatures which help to get additional insight into the flow dynamics ...

when flow passes over the tube bundles, energy of flow transfers to the tubes. the fluid induced vibrations (fiv) imposed on the tubes is one of the important problems in analyzing the tube bundles and causes several problems. in this work, first, laminar flow around circular cylinder asymmetrically in a channel is simulated. the reynolds number is 20 and 100. the lift forces to tube are not ze...

Early in 1989, the late Marcel Golay derived a theory for turbulent flow capillary gas chromatography. He assumed that the flow pattern under turbulent conditions consists of a turbulent core separated from the tube wall by a very thin laminar flow layer. Further, it was assumed that the viscosity and the diffusion constant are uniform within the turbulent core. The core radius is a fraction p ...

The transition to turbulence in pipe and plane Couette flow differs from the better understood situation of Taylor-Couette or Rayleigh-Bénard flow in that the laminar profile is stable against infinitesimal perturbations for all Reynolds numbers. Moreover, even when turbulent flow is established, it can spontaneously return to laminar flow. These observations are compatible with the formation o...

Prior to the 2001 CMER pilot study, several TFW cooperators conducted independent field studies of the distribution of perennial and seasonal headwater streams (Table 1). All of the studies were conducted during the summer low flow seasons of 1998 or 2000, in part, to evaluate proposed regulatory guidelines that differentiate non-fish-bearing headwater streams on the basis of the seasonal flow ...

In this research we have implemented the Random Vortex Method to calculate velocity fields of fluids inside open cavities in both turbulent and laminar flows. the Random Vortex Method is a CFD method (in both turbulent and laminar fields) which needs the Schwarz-Christoffel transformation formula to map the physical geometry into the upper half plane. In some complex geometries like the flow in...