Related papers: Airfoil Boundary Layer Bubble Separation and Trans…
Combined pitching-and-surging of an airfoil at the identical frequency (i.e., synchronously), at four different phase-differences, was investigated theoretically and experimentally. The most general unsteady theoretical formulation was…
The spatio-temporal dynamics of separation bubbles induced to form in a fully-developed turbulent boundary layer (with Reynolds number based on momentum thickness of the boundary layer of 490) over a flat plate are studied via direct…
Large eddy simulations are performed to study tonal noise generation by a NACA0012 airfoil at an angle of attack ${\alpha = 3}$ deg. and freestream Mach number of ${M_{\infty} = 0.3}$. Different Reynolds numbers are analyzed spanning ${0.5…
The shock-boundary layer interaction over the convex wall of a supersonic turbine vane is studied with a focus on extreme separation bubble events and the interplay between the bubble, streaks, and streamwise vortices. The present analysis…
A large eddy simulation is performed to study secondary tones generated by a NACA0012 airfoil at angle of attack of $\alpha = 3^{\circ}$ with freestream Mach number of $M_{\infty} = 0.3$ and Reynolds number of $Re = 5 \times 10^4$. Laminar…
In nature, phase transitions prevail amongst inherently different systems, while frequently showing a universal behavior at their critical point. As a fundamental phenomenon of fluid mechanics, recent studies suggested laminar-turbulent…
This work aims to numerically investigate the linear global instability of long separation bubbles origin from the changes in the adverse pressure gradient inside a laminar flat plate boundary layer disturbed by placing a bluff body with…
The flow over a NACA0012 airfoil at a moderate Reynolds number Re = 50,000 and angle of attack of alpha = 3 degrees is investigated using the lattice-Boltzmann method (LBM). The LBM solutions are computed in direct numerical simulation…
A comprehensive and detailed overview of the flow topology over a cambered NACA 65(1)-412 airfoil at Re = 20,000 is presented for angles of attack ranging from 0{\deg} to 10{\deg} using high-order direct numerical simulations. It is shown…
Experiments were conducted in a low-turbulence wind tunnel to investigate the efficacy of localised acoustic forcing upon the dynamics and stability of the flow on a cambered, wall-bounded airfoil over a range of Reynolds numbers (Re) where…
In standard (symmetry-breaking) first-order phase transitions, the frictional pressure on expanding bubble walls can be dominated by transition radiation -- the emission of a gauge boson with phase-dependent masses as particles present in…
This study investigates laminar boundary layer separation over a fully porous Gaussian bump using pore-resolved direct numerical simulations. The bump is formed by randomly packed spheres. Compared to a solid bump, the porous surface…
We find actual evidence, relying upon vorticity time series taken in a high Reynolds number atmospheric experiment, that to a very good approximation the surface boundary layer flow may be described, in a statistical sense and under certain…
This work describes an experimental investigation on the mixing induced by a swarm of high Reynolds number air bubbles rising through a nearly homogeneous and isotropic turbulent flow. The gas volume fraction $\alpha$ and the velocity…
Bubbles play an important role in the transport of chemicals and nutrients in many natural and industrial flows. Their dispersion is crucial to understand the mixing processes in these flows. Here we report on the dispersion of millimetric…
We investigate by direct numerical simulations the flow that rising bubbles cause in an originally quiescent fluid. We employ the Eulerian-Lagrangian method with two-way coupling and periodic boundary conditions. In order to be able to…
The separated flow response to single and multiple burst mode actuation over a 2-D airfoil at $12^o$ angle of attack was studied experimentally. For the single-burst actuation case, surface pressure signals were correlated with the…
Direct numerical simulations are carried out to investigate the flow features responsible for secondary tones arising in trailing-edge noise at moderate Reynolds numbers. Simulations are performed for a NACA 0012 airfoil at freestream Mach…
A quantitative analysis illustrating salient features of a Laminar Separation Bubble (LSB), its transition forming coherent structures, and associated heat transfer has been performed on a flat plate for varying free stream turbulence (fst)…
Transonic buffet is an unsteady flow phenomenon that limits the safe flight envelope of modern aircraft. Scale-resolving simulations with span-periodic boundary conditions are capable of providing new insights into its flow physics. The…