Behzad Reza Ahrabi

Behzad Reza Ahrabi
The Boeing Company · Boeing Research and Technology

PhD

About

22
Publications
5,182
Reads
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181
Citations
Introduction
Behzad R. Ahrabi is a researcher in the field of Computational Fluid Dynamics (CFD). He works at Boeing Research & Technology (BR&T) as an Aerodynamics Engineer and he is involved in development of state-of-art computational simulation technologies. Before that he worked for four years with Dimitri J. Mavriplis (at the University of Wyoming) on emerging solver technologies for massively parallel applications. Behzad finished his Ph.D. in Computational Engineering under William K. Anderson at the SimCenter, the National Center for Computational Engineering, at the University of Tennessee at Chattanooga.
Additional affiliations
September 2019 - present
The Boeing Company
Position
  • Engineer
Description
  • Development of finite-element methodologies for simulation of compressible turbulent flows
April 2017 - September 2019
University of Wyoming
Position
  • Researcher
August 2011 - August 2015
University of Tennessee at Chattanooga
Position
  • Research Assistant

Publications

Publications (22)
Article
The time-spectral method is a fast and efficient scheme for computing the solution to temporal periodic problems. Compared to traditional backward difference implicit time-stepping methods, time-spectral methods incur significant computational savings by using a temporal Fourier representation of the time discretization and solving the periodic pro...
Article
This paper presents an efficient and highly-parallelizable preconditioning technique for Newton–Krylov solvers. The proposed method can be viewed as a generalization of the implicit line smoothing technique by extending the groups of implicitly-solved unknowns from lines to blocks. The blocks are formed by partitioning the computational domain such...
Article
Blade-resolved numerical simulations of wind energy applications using full blade and tower models are presented. The computational methodology combines solution technologies in a multi-mesh, multi-solver paradigm through a dynamic overset framework. The coupling of a finite volume solver and a high-order, hp-adaptive finite element solver is utili...
Conference Paper
Full-text available
Two high-order finite-element solvers are used to simulate two 3D benchmark problems provided by the NASA Turbulence Modeling Resource (TMR) website. The first problem is a subsonic turbulent flow over a hemisphere-cylinder body at angles of attack of 5 and 19 degrees. The second problem is a transonic turbulent flow an ONERA M6 wing at angles of a...
Conference Paper
Full-text available
This paper extends the application of traditional implicit line smoothers to high-order continuous finite-element methods. It is shown that for high-order continuous finite-element discretizations, the interconnections of the degrees of freedom on an implicit line form a banded matrix which is wider than tridiagonal, but still can be factorized com...
Article
In this study, an adjoint-based hp-adaptation algorithm has been developed within a Petrov-Galerkin finite-element method. The developed mesh adaptation algorithm is able to perform non-conformal mesh adaptations. To account for hanging nodes in a consistently manner, the constrained approximation method has been utilized. Hierarchical basis functi...
Conference Paper
Full-text available
1. The objective of the present study is to investigate and develop robust, efficient, and scalable multilevel solution strategies and preconditioning techniques for stabilized finite-element flow solvers. The proposed solution strategy is essentially a p-multigrid approach in which the solution on the mesh with lowest polynomial degree (p=1) is so...
Article
Full-text available
A high-order Petrov–Galerkin finite element scheme is used to compute turbulent flow over a NACA 0012 airfoil at a freestream Mach number of 0.15, an angle of attack of 10 deg, and a Reynolds number based on the airfoil chord of 6 million. Results are obtained on a series of grids available on the NASA Turbulence Modeling Resource Web site and are...
Conference Paper
Full-text available
A high-order Discontinuous Galerkin (DG) solver is used to simulate three turbulent flow simulations. Two of these simulations come from the NASA turbulence modeling resource and include turbulent flow over a hemisphere-cylinder and turbulent flow over a 3D bump in a channel. The third simulation is the DLR-F11 from the second high-lift prediction...
Thesis
Full-text available
After several decades of development, higher-order finite-element methods are now being considered for realistic and large scale Computational Fluid Dynamics (CFD) simulations. This necessitates further studies on utilization of mesh adaptation techniques in order to reach reliable solutions at minimal computation cost. In this study, adaptation ca...
Conference Paper
Full-text available
In this paper enhancements to a stabilized finite-element overset scheme are presented. First, the recently proposed grid overlapping method referred to as elliptic hole cutting has been modified to be more suitable for parallel implementation. These modifications dramatically reduce the amount of searching and interpolation required to establish t...
Conference Paper
Full-text available
In this study, an adjoint-based hp-adaptation algorithm has been developed within a Petrov-Galerkin finite-element method. The developed mesh adaptation algorithm is able to perform non-conformal mesh adaptations. To consistently account for hanging nodes, the constrained approximation method has been utilized. Hierarchical basis functions have bee...
Conference Paper
Full-text available
This paper aims to report the computational research carried out to study the flow in a diffusing S-duct using Computational Fluid Dynamics (CFD). Computations were carried out for the two cases of an S-duct without flow control devices and an S-duct with passive flow control devices (vortex generators). The complexities of the flow field such as s...
Conference Paper
Full-text available
A high-order Petrov-Galerkin finite-element scheme is used to compute turbulent flow over a NACA 0012 airfoil at a free stream Mach number of 0.15, an angle-of-attack of ten degrees, and a Reynolds number based on the airfoil chord of six million. Results are obtained on a series of grids available on the NASA Turbulence Modeling Resource website a...
Conference Paper
Full-text available
A dynamic adaptation approach has been implemented within a streamline/upwind Petrov-Galerkin (SUPG) finite-element method. The proposed adaptation is able to perform h-, p-, and hp-refinement/derefinement and utilized within any Galerkin formulation. To demonstrate the developed methodology, the Euler and Reynolds Average Navier-Stokes (RANS) equa...
Conference Paper
Full-text available
This paper aims to report the computational research carried out to study the flow in a diffusing S-duct. Using Computational Fluid Dynamics (CFD), this study seeks to validate the numerical results by comparing them to experimental data reported in AIAA Propulsion Aerodynamics Workshop (PAW01). For this purpose, RANS equations were solved using an...
Article
Developing incompressible viscous fluid flow and heat transfer in a curved annular pipe is studied numerically. The governing equations consisting of continuity, full Navier–Stokes, and energy equations are solved using a projection method based on the second order central difference discretization. Considering the outer wall to be adiabatic, two d...

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