RESEARCH EXPERIENCE

Department of Aerospace and Mechanical Engineering, The University of Arizona (Jan. 2011 __ cont)

Graduate Research Assistant __ Computational Fluid Dynamics Laboratory

PI: Prof. Hermann F. Fasel

A. Tasks

• Performed all aspects of computational fluid dynamics constituted of employing Navier-Stokes based codes, pre- and post-processing.
• Wrote peer-reviewed conference and high-impact journal papers
• Frequently presented my research at major aeronautical conferences.
• Contributed in writing research grant proposals, final grant reports and technical reports.
• Administrated the high-performance computing center in CFDL.

B. Research Projects

• Performing highly resolved direct numerical simulations to investigate laminar-turbulent transition in subsonic boundary layers with particular focus on a ‘natural’ breakdown to turbulence as it occurs in wind-tunnels and/or free-flight.
• Examining the interaction of transition and separation and its control for separation bubbles over swept aircraft wings subjected to unsteady pressure gradients.
• Investigated the interaction between free-stream turbulence and the active flow separation control strategy using high-fidelity numerical simulations and comprehensive stability analyses.
• Developed robust and efficient high-order numerical algorithms aimed at high-fidelity large-scale numerical simulations of flow around complex geometries.
• Investigated the effects of sweep angle on the complex interaction of transition and separation with specific emphasis on understanding the role of crossflow instability mechanism.
• Explored complex topology and flow structures of three-dimensional separation bubbles using DNS, with particular focus on the effect of aspect ratio.
• Performed landmark numerical simulations of pulsed vortex generator jets flow control of laminar boundary-layer separation in the presence of realistic free-stream turbulence.
• Carried out a unique research consisting of high-fidelity numerical simulations, primary and secondary linear stability analyses as well as modal decomposition techniques, for physics-based understanding of the physical mechanisms governing separation in general and the laminar-turbulent transition process in particular in laminar separation bubbles, in the presence of free-stream turbulence.

C. Code Development

• Developed a high-order accurate Navier-Stokes code capable of handling complex geometries using advanced computational algorithms.
• Developed a novel, efficient and high-order accurate sharp-interface method for solving the 2D Poisson equation on irregular domains, based on a combination of a fourth-order compact finite difference scheme and a multiscale multigrid method.
• Developed an efficient fourth-order sharp immersed interface method for solving 3D Poisson equation with arbitrary boundaries, based on the combination of the compact finite difference scheme and the multigrid preconditioned stabilized biconjugate-gradient method.
• Developed massively parallel state-of-the-art modal decomposition tools.
• Developed an efficient parallel secondary instability (SI) solver without additional assumptions as required by the standard SI analysis.
• Developed a linearized Navier-Stokes solver (without using any additional assumptions as required by LST and PSE) capable of investigating 2D & 3D convective and global instability mechanisms.
• Optimized existing computational tools, thus reducing compute time significantly for large-scale simulations.

Department of Aerospace Engineering, Tehran Polytechnic University (Sep. 2008 __ Oct. 2010)

Undergraduate Researcher

• Developed free-transition model on the basis of coupling the RANS equations with empirical and semi-empirical correlations used for transition onset and extent prediction.
• Investigated lift and drag characteristics of a geometrically modified airfoil which utilized the backward facing step to explore the possibility of enhancing airfoil aerodynamic performance by trapped vortex lift augmentation.
• Explored three-dimensional flow over backward facing step with particular focus on the effect of side walls on the flow topology and mean flow characteristics.