On the origin of spanwise vortex deformations in laminar separation bubbles

This work investigates the three-dimensional, spatio-Temporal flow development in the aft portion of a laminar separation bubble. The bubble is forming on a flat plate geometry, subjected to an adverse pressure gradient, featuring maximum reverse flow of approximately 2Â % of the local free-stream velocity. Time-resolved velocity measurements...

Experimental study of the flow in the wake of a stationary sphere immersed in a turbulent boundary layer

In many applications, finite-sized particles are immersed in a turbulent boundary layer (TBL) and it is of interest to study wall effects on the instantaneous shedding of turbulence structures and associated mean velocity and Reynolds stress distributions. Here, 3D flow field dynamics in the wake of a prototypical, small sphere (D+=50, 692&lt...

Response of a laminar separation bubble to impulsive forcing

The spatial and temporal response characteristics of a laminar separation bubble to impulsive forcing are investigated by means of time-resolved particle image velocimetry and linear stability theory. A two-dimensional impulsive disturbance is introduced with an alternating current dielectric barrier discharge plasma actuator, exciting...

Auto-generation by interaction of weak eddies

For channel flow, we explore how the interaction of weak eddies produces additional eddies by means of auto-generation. This is done by DNS of two eddies with different initial strengths, initial sizes and initial stream-wise spacing between them. The numerical procedure followed is similar to Zhou et al[1]. The two eddies merge into a single...

Benchmarking high order finite element approximations for one-dimensional boundary layer problems

In this article we investigate the application of high order approximation techniques to one-dimensional boundary layer problems. In particular, we use second order differential equations and coupled second order differential equations as case studies. The accuracy and convergence rate of numerical solutions obtained with Lagrange, Hermite, B...

An analytical kinetic model for chemical-vapor deposition of pureB layers from diborane

In this paper, an analytical model is established to describe the deposition kinetics and the deposition chamber characteristics that determine the deposition rates of pure boron (PureB-) layers grown by chemical-vapor deposition (CVD) from diborane (B2H6) as gas source on a non-rotating silicon wafer. The model takes into consideration the...

Tracking of vortices in a turbulent boundary layer

A study on the application of two different acoustic analogies to experimental PIV data

The aim of the present study is to compare two different acoustic analogies applied to time-resolved particle image velocimetry (PIV) data for the prediction of the acoustic far-field generated by the flow over a rectangular cavity. We consider the model problem of sound radiating from an open, two-dimensional, shallow cavity with an aspect...

Experimental study on dielectric barrier discharge actuators operating in pulse mode

An experimental investigation is performed on the operation of dielectric barrier discharge plasma actuators used as manipulators of secondary and unsteady flow structures such as boundary layer instabilities or shedding vortices. The actuators are tested mainly in pulse mode. High sample rate hot-wire measurements of the induced velocity field...

Wind and boundary layers in Rayleigh-Bénard convection. II: Boundary layer character and scaling

Wind and boundary layers in Rayleigh-Bénard convection. I: Analysis and modeling

Spectral analysis of boundary layers in Rayleigh-Bénard convection

On the spatial linear growth of gravity-capillary water waves sheared by a laminar air flow

The initial growth of mechanically generated small amplitude water waves below a laminar air stream was examined numerically and experimentally in order to explore the primary growth mechanism, that is, the interfacial instability of coupled laminar air and water flows. Measurements of the laminar velocity profile in the air over the water...

A study on the transmission of sound through flow ducts of varying cross section

A study is made of sound propagation through axially varying ducts with mean flow. Several analytical and numerical approaches are considered, and discussed with respect to their possibilities and limitations. Two new analytical theories, relevant for low and for high frequencies, are worked out in some detail. A fortuitously available *)...

A quasi-simultaneous calculation method for strongly interacting viscous flow around an infinite swept wing

An outline is presented of a new code, called VISIAN, for the analysis of aerodynamic flows with strong viscous-inviscid interaction. The code is based on the recently developed quasi-simultsuieous method for the calculation of strongly interacting boundary layers. The feasibility of this method has already been demonstrated liy means of a...