相关论文: Destruction of wall-bounded vortices using synthet…
The vortex dynamics resulting from the interaction of synthetic jets with turbulent boundary layers was investigated experimentally using stereoscopic particle image velocimetry (SPIV). Three aspect ratio 18 rectangular orifice geometries…
There are numerous devices currently known with the purpose of reducing the irregularity of the flow upstream of the propeller and to decrease by that means the propeller-induced vibration and noise. Many of these devices are wing-shaped…
This study investigates a mechanism of controlling separated flows around an airfoil using a synthetic jet (SJ). A large-eddy simulation (LES) was performed for a leading-edge separation flow around a NACA0015 airfoil at the chord Reynolds…
Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generator jets (VGJs) was investigated using direct numerical simulations. Both control strategies were found to be effective in controlling the…
To investigate the influence of the orifice geometry on near-field coherent structures in a jet, Fourier-POD is applied. Velocity and vorticity snapshots obtained from tomographic particle image velocimetry at the downstream distance of two…
G\"{o}rtler vortices develop along concave walls as a result of the imbalance between the centrifugal force and radial pressure gradient. In this study, we introduce a simple control strategy aimed at reducing the growth rate of G\"{o}rtler…
We perform direct numerical simulations (DNS) of actively controlled laminar separated wakes around low-aspect-ratio wings with two primary goals: (i) reducing the size of the separation bubble and (ii) attenuating the wing tip vortex.…
In confined rotating convection, a strong zonal flow can develop close to the side wall with a modal structure that precesses anti-cyclonically (counter to the applied rotation) along the side wall. It is surmised that this is a robust…
G\"{o}rtler vortices in boundary layer flows over concave surfaces are caused by the imbalance between centrifugal effects and radial pressure gradients. Depending on various geometrical and/or freestream flow conditions, vortex breakdown…
The purpose of this work is to analyze the flow due to a potential point vortex pair in the vicinity of a symmetry line (or "wall"), in order to understand why the presence of the wall, even far from the vortices, accelerates fluid mixing…
The interaction of trailing and leading vortex structures in low Reynolds number forced (varicose) jet with coflow is studied using Direct Numerical Simulation (DNS), where we report the dynamics of these vortices for a range of varying…
We present an experimental study of reactive control of turbulent jets. We target axisymmetric disturbances associated with coherent structures, which are known to underpin the peak sound radiation of turbulent jets. We first consider a…
An array of twelve circular-orifice synthetic jet actuators (SJAs) was used to provide the unsteady forcing required for flow separation control over a National Advisory Committee for Aeronautics (NACA) 0025 airfoil at a chord-based…
We study the dynamics of vortices in an asymmetric ring channel driven by an external current I in a Corbino setup. The asymmetric potential can rectify the motion of vortices and cause a net flow without any unbiased external drive, which…
Introducing a fluid microjet into the boundary layer to increase fluid momentum and hence delay separation is a method for actively controlling a flow separation region. The present work numerically analyzed the control of a separation…
Velocity profiles and wall shear stress values in the wall jet region of planar underexpanded impinging jets are parameterized based on nozzle parameters (stand-off height, jet hydraulic diameter, and nozzle pressure ratio). Computational…
Three-dimensional unsteady numerical simulations are performed to investigate the effects of blowing ratio $C_B$ ($0.85 < \overline{U}_j/U_\infty < 1.7$), stroke ratio $L^+$ ($10.6 < \overline{U}_j /(fd) < 21.3$), and boundary-layer height…
Closed-loop control of turbulent flows is a challenging problem with important practical and fundamental implications. We perform closed-loop control of forced, turbulent jets based on a wave-cancellation strategy. The study is motivated by…
This paper presents a study on wave cancellation in forced jets. Building on recent work on real-time control of forced turbulent jets [1,2], we here assess the effect of jet upstream conditions and nonlinearity on wave-cancellation…
Patterns of vorticity in the wake of a single rectangular winglet (vortex generator) embedded in a turbulent boundary layer have been studied using Stereoscopic Particle Image Velocimetry (SPIV). The winglet was mounted normally to a flat…