The understanding of flow over open cavities is relevant for a wide range of applications,
from car sunroof to aircraft weapon bay, landing gear well and instrumentation/optical cavities.
Self-sustained oscillations inside the cavity generate intense pressure fluctuations that can lead
to structural damage and failure of components. Linear stability analysis and direct numerical simulations
(DNS) of two- and three-dimensional compressible flow over open cavities are performed to investigate
the flow physics and the basic mechanisms underlying the cavity oscillations.
DNS of 2D cavity flow with shear-layer oscillations (Rossiter mode II): dilatation (top) and vorticity magnitude (bottom)Vorticity magnitude from DNS of 2D cavity flow at higher Reynolds NumberIsosurface of spanwise vorticity from DNS of 3D cavity flow
For the next-generation of hypersonic vehicles, efficient laminar flow control technologies that delay
laminar-turbulent transition are required to reduce heat transfer rates, and thereby reduce the weight and
complexity of necessary thermal protection systems. Passive ultrasonic absorptive coatings (UAC), which consist
of thin perforated layer of regular microstructure,
have been shown to significantly increase laminar run. As part of a multidisciplinary effort to design and
fabricate UAC prototypes, the current research focuses on theoretical modeling and direct numerical simulations
(DNS) of these porous coatings.
As a branch of computational fluid dynamics, computational aeroacoustics is dedicated to the study of
sound generated via aerodynamic interactions with surface and/or turbulent fluid motions. For most practical
applications such as train or aircraft noise certification, far-field noise predictions are made through the
use of an acoustic analogy method, such as the Ffowcs Williams-Hawkings (FW-H) equation. This efficient method
has been applied to a wide range of problems, from helicopter noise, to jet predictions and landing gear noise.
Landing gear predictions with LBMTandem cylinder aeroacoustic benchmark
For wings at high angles of attack in unsteady flow conditions, the ability to increase lift or
delay the onset of flow separation via active flow control is of interest. Such ability is particularly
relevant for micro-air vehicles (MAV) performing rapid maneuvers or responding to gusting flows. As a next
step towards a better understanding of unsteady flow control of MAV, simulations can be used to investigate
the unsteady flow over 3D planform wing representative of full-size MAV, including the effect of leading edge blowing.
Smoke visualization of flow over 3D wing: continuous pulsed-jet actuation (left) and no forcing (right)Instantaneous vorticity magnitude in LBM simulation (angle of attack: 19 deg)
This research is part of a broader ongoing effort to improve understanding and develop predictive
capabilities of propulsive jet noise, through high-fidelity physics-based simulations with the unstructured
compressible flow solver Charles™ developed at Cascade Technologies. Charles™ is currently being used to
investigate a wide range of high-speed unsteady flow processes for various complex configurations,
including impinging flows, nozzle with chevrons, circular and rectangular jets, faceted military-style nozzle, etc.
Isosurface of vorticity magnitude colored by streamwise velocity
LES of heated supersonic over-expanded jet from round nozzle with chevronsInstantaneous temperature field
LES of heated supersonic over-expanded jetVorticity magnitude and grid cuts.
LES of isothermal supersonic ideally-expanded jet
