Abdellah Hadjadj

Professeur - INSA de Rouen

  • Research Activities : High-Performance Computing, Computational Fluid Dynamics, Turbulence Modeling, Wall-Bounded Flows, Turbulent Mixing, Micro-fluidics.
  • Teaching Activities : Turbulence modeling, Numerical Methods, OpenFoam. The courses are given to students from different INSA Departments ; Mechanical Engineering (MECA), Energetic & Propulsion (EP), Industrial Safety & Environment (MRIE) Departments., as well as EFE Master Research.

Groupe de recherche :
Turbulence et mélange

This work presents an overview of the main research activities in the area of internal and external aerodynamics. The current research is motivated by the desire to develop reliable numerical tools for predicting complex turbulent flows in real applications, especially for problems including sharp fluid interface (discontinuities), interacting with instabilities and turbulence.

A variety of problems encountered in supersonic flows, such as supersonic turbulence including shock/shock and shock/boundary layer interactions, shear-layer instability and transient flows are considered.

The results of this study provide a better understanding of the main characteristics of complex flows that are not easily accessible experimentally, and may be useful for flow controlling and practical aerodynamics design and improvement.

Compressible Navier-Stokes solvers using high-order shock-capturing schemes and turbulence models are developed for solving gas-dynamics problems.

Numerical schlieren pictures as well as computed interferogram techniques are used to visualize the major features of physical phenomena occurring in such flows. A variety of test problems encountered in supersonic flows, such as supersonic turbulence including shock/shock and shock/boundary layer interactions, shear-layer instability and transient flows are considered. The results of this study provide in general better understanding of the main characteristics of complex flows that are not easily accessible experimentally, and may be useful for flow controlling and practical aerodynamics design and improvement.

Example 1 : Shock-wave propagation in a round tube undergoing a sudden expansion

After multiple wall reflexions, the transmitted shock quickly reaches the end of the test section, leaving behind it a highly disturbed flow. As time proceeds, the flow becomes more and more complex resulting in extremely complicated shock-strain rate interactions, multiple shock reflections, acoustic wave propagations, vorticity dynamics, expansion and other gas dynamics instabilities.

GIF - 37.1 ko
Propagation of shock wave (Ms=1.5) in round tube with sudden expansion. Numerical schlieren picture.

see the file amorcage.mov at bottom of this page.

Example 2 : Nozzle start-up

GIF - 42.7 ko
Enlargement of the transient flow-field near the nozzle wall region showing shock waves bifurcations and Richtmyer-Meshkov instability of the contact discontinuity in between two shocks during the earlier stage of the Vulcain nozzle start-up process.

This example concerns the transient flow developing in the Vulcain nozzle (designed for the European rocket Ariane V) during the engine start-up. After burning in the combustion chamber, the exhaust gases are expanded in the nozzle to deliver an optimal thrust to the launcher. The starting process begins with the primary shock (blast wave) entering the nozzle and ends when a quasi-steady flow has been achieved.

Example 3 : Large-eddy simulation of shock/boundary layer interaction

This example concerns numerical simulation of supersonic turbulent flows when shock/turbulent boundary layer interaction occurs. Large eddy simulation is used to investigate unsteady mechanisms. Since a shock-capturing scheme is used, an hybrid numerical scheme has been developed to reduce its dissipative properties. Computations results are in very good agreement with experimental data and DNS. Especially, oscillations of the reflected shock occurring at low frequencies are observed, in agreement with experimental investigations. Moreover, simulations reveal the presence of such frequencies inside the recirculation bubble. This point gives credit to the hypothesis which presents the instabilities of the reflected shock as a consequence of the dynamic properties of the separated zone.

GIF - 20.3 ko
Boundary layer structure in the absence of interacting shock wave. Instantaneous longitudinal velocity fluctuation field in x-z plane at y+=100 (top) and three-dimensional view of vortex structure (bottom).
JPEG - 520.1 ko
Instantaneous iso-surface of the second invariant of the velocity gradient tensor Q = 0,01Qmax colored by the density field, showing the shock/boundary layer interaction

Portfolio

photo

Fichiers ...

CAF17

2 Mo

JFM17

1 Mo

CAM17

1.7 Mo

JoT6a

2.1 Mo

CAF6a

2.5 Mo

AST6a

5.5 Mo

CCP6a

1.1 Mo

FTC6a

2.9 Mo

SWJ5a

2 Mo

CaF5a

1.3 Mo

CaF5a

1.3 Mo

JPP5a

1.9 Mo

JPP5a

1.9 Mo

PoF5a

2.4 Mo

IJF5a

5.4 Mo

AST5a

2.8 Mo

IJH5a

6 Mo

POF4a

1010.1 ko

NHT4a

2.5 Mo

NHT4a

2.5 Mo

PhD-LB

4.2 Mo

PhD-AM

47.1 Mo

PhD-SD

3.6 Mo

PhD-YP

11 Mo

PhD-DT

23.7 Mo

PhD-NO

13.1 Mo

PhD-OT

26.1 Mo

PhD-OB

8.9 Mo

PhD-ED

23.7 Mo

EDP

23.7 Mo

PHD

10.5 Mo

HDR

8.2 Mo

JSC0a

2.5 Mo

JCP1a

1.7 Mo

PRE1a

646.5 ko

IJNF2a

4.1 Mo

IJNE2a

2.7 Mo

CCP2a

2.2 Mo

AIA2a

5.4 Mo

SWJ3d

1.3 Mo

SWJ3c

1 Mo

SWJ3b

1.2 Mo

POF3a

2.2 Mo

JFM4a

2.3 Mo

AIP3a

306.1 ko

amorcage.mov

Propagation of shock wave ...

12.5 Mo

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