Computational Aero-sciences Laboratory

Research Areas

1. High-speed compressible jets

  • Jets are free shear layers harboring a rich set of physical phenomena including vorticity dynamics, turbulent mixing and acoustic emissions.
  • We utilize experimentally anchored high-fidelity simulations to understand the evolution of coherent structures and fine-scale turbulence in low-subsonic to high supersonic operating conditions.
  • These studies are of relevance to thrust and noise control in commercial turbofan as well as military-style turbojet engines.


2. Aeroacoustics

  • Exhaust jets produce a lot of sound
  • A first principle-based noise source identification and control is still an active field of research
  • We use a novel fluid-thermodynamic (FT) decomposition to delineate the feeble but highly detrimental acoustic component from the more energetic hydrodynamic component
  • This makes quantification of sound and identification of its sources significantly easier, and even yields insight into its controllability


Delineated turbulence and sounds fields of a jet - 


3. Hydrodynamic stability and global analysis

  • Linear dynamics of Navier-Stokes equations yield significant insights into the stability of fluid systems, without doing expensive simulations
  • Shown is a classical lid-driven cavity problem with its leading instability mode
  • We explore operator and operator-free methods to expand the utility of linear analysis to compressible flows in three-dimensional space
  • This is critical in identifying unsteadiness and coherent structures in relatively complex flows of practical interest 


  • Mean flow perturbation (MFP) is an operator-free perturbation technique which gives accurate estimates of leading scales of unsteadiiness in 3D flows
  • It has also been shown to accurate capture prominent acoustic emissions from free-shear layers


Global stability analysis - 

Numerical linearization instability mode extraction


4. Hypersonic flows - stability, transition, and turbulence

  • High speed flows, generally above Mach 4 are qualitative different from subsonic and supersonic flows in terms of stability and physical characteristics
  • Futuristic civilian transport, space exploration and military technology all relies on accurate prediction and control of fluid flow in this regime
  • A major problem encountered here is transition - transition induces increased heating and drag on high-speed vehicles
  • We study the role of instabilities in perturbing these flows, causing transition to turbulence

A flared cone model - nonzero pressure gradient boundary layer Mach 6             NASA Compression corner - Shock=boundary-layer integration Mach 5.4





Theoretical and numerical analysis of radiation form cooled-hypersonic boundary layers

Turbulent spots and their evolution



5. Numerics

3-D, Unsteady, Compressible Navier-Stokes equations solved on curvilinear coordinates

Temporal Schemes:

Explicit - Rk3

Implicit - B&W

Spatial schemes:

  • Smooth solution fields:
    • 6th order compact scheme
    • 8th order Pade filter
    • 5th/7th order WENO reconstruction
  • Compressible scenarios – shock dynamics
    • Roe flux calculation
    • 3rd order spatial reconstruction – MUSCL based
    • van- Leer harmonic limiter for stabilization
  • High-fidelity computations for transition and turbulent flows
    • Hybridization of compact schemes with the Riemann solver – informed by shock detection routines


6. Aero-propulsion

  • Characterize and quantify the performance of aero-propulsion systems
  • Utilize theorical models and simplified analyses to identify sensitive flow features
  • Employ turbulence modeling and high-fidelity simulations to evaluate performance deviations in relevant systems
  • Current flow problems studied include:
  • Non-axisymmetric, heated, over-expanded jets
  • Supersonic inlets


Last Updated: Monday, October 19, 2020 at 9:16 AM