Ali Uzun

Education

• Ph.D. in Aeronautics & Astronautics, Purdue University, 2003
• Master of Science in Mechanical Engineering, Purdue University, 1999
• Bachelor of Science in Aeronautical Engineering, Middle East Technical University, 1997

Work Experience

• Senior Research Scientist, National Institute of Aerospace, 2015-present
• Assistant Scholar Scientist, Florida Center for Advanced Aero-Propulsion, Florida State University, 2011-2015
• Research Associate, Florida State University, 2003-2011

Research Areas/Expertise

• Computational Fluid Dynamics
• Turbulence Simulations
• Hydrodynamic Stability
• Computational Aeroacoustics
• High-Performance Computing

Current Research

High-Resolution Turbulence Simulations of Separated Flows

Smooth-body flow separation is an important problem of interest, due to its appearance in many technological applications. The problem involves a boundary layer attached to a solid surface, which becomes detached from the surface after interaction with an adverse pressure gradient generated by a change in body contour or the presence of a shock. Flow separation often leads to increased aerodynamic drag, stall and reduced system performance. Such separated flows are generally difficult to predict because they involve high-Reynolds-number turbulence. High-resolution simulations are being carried out in the form of wall-resolved large-eddy simulations to investigate the flow separation phenomenon under subsonic and transonic flow conditions.

Extreme-Scale Direct Numerical Simulations of Turbulence

Latest developments in computing technology present exciting opportunities for the application of direct numerical simulation (DNS) methods to practical problems. Even though much more computationally expensive than lower-fidelity simulation tools, a properly-performed DNS eliminates the uncertainties associated with grid under-resolution and turbulence modeling errors, which are always present in lower-fidelity simulations. Our objective on the current state-of-the-art and upcoming exascale computing systems is to perform DNS with unprecedented levels of grid resolution for very challenging aerodynamics problems, such as the transonic flowfield over an entire aircraft wing. In preparation for these planned extreme-scale calculations, the computational algorithms used in our flow solver are being modified and enhanced in order to harness the full potential of the latest and upcoming computing architectures.

Publications

Uzun, A. and Malik, M. R., “Wall-Resolved Large-Eddy Simulations of Transonic Shock-Induced Flow Separation,” AIAA Journal, in press, 2019.

Davis, T. B., Uzun, A. and Alvi, F. S., “Optimal Disturbances and Large-Scale Energetic Motions in Turbulent Boundary Layers,” Journal of Fluid Mechanics, Vol. 860, February 2019, pp. 40 – 80.

Uzun, A. and Malik, M. R., “Wall-Resolved Large-Eddy Simulations of Transonic Shock-Induced Flow Separation,” in Proceedings of the 2018 AIAA Fluid Dynamics Conference, 25-29 June 2018, Atlanta, Georgia.

Nicholson, G., Zhang, C., Duan, L., Malik, M., Li. F. and Uzun, A., “Direct Numerical Simulation of Receptivity to Roughness in a Swept-Wing Boundary Layer at High Reynolds Numbers,” in Proceedings of the 2018 AIAA Fluid Dynamics Conference, 25-29 June 2018, Atlanta, Georgia.

Uzun, A. and Malik, M. R., “Large-Eddy Simulation of Flow over a Wall-Mounted Hump with Separation and Reattachment,” AIAA Journal, Vol. 56, No. 2, February 2018, pp. 715 – 730.

Uzun, A., Davis, T. B., Alvi, F. S. and Hussaini, M. Y., “Optimally Growing Boundary Layer Disturbances in a Convergent Nozzle Preceded by a Circular Pipe,” Theoretical and Computational Fluid Dynamics, Vol. 31, No. 3, June 2017, pp. 317 – 348.

Lee, H., Uzun, A. and Hussaini, M. Y., “Identification of Jet Noise Source Using Causality Method Based on Large-Eddy Simulation of a Round Jet Flow,” International Journal of Aeroacoustics, Vol. 16, No. 1+2, March 2017, pp. 78 – 96.

Uzun, A. and Malik, M. R., “Wall-Resolved Large-Eddy Simulation of Flow Separation Over NASA Wall-Mounted Hump,” in Proceedings of the 55th AIAA Aerospace Sciences Meeting, 9-13 January 2017, Grapevine, Texas.

Uzun, A., Alvi, F. S., Colonius, T. and Hussaini, M. Y., “Spatial Stability Analysis of Subsonic Jets Modified for Low-Frequency Noise Reduction,” AIAA Journal, Vol. 53, No. 8, August 2015, pp. 2335 – 2358.

Taligoski, J., Fernandez, E., Uzun, A. and Kumar, R., “Study of the Roll Orientation Effects on Vortex Asymmetry on a Conical Forebody at High Angles of Incidence,” in Proceedings of the 53rd AIAA Aerospace Sciences Meeting, 5-9 January 2015, Kissimmee, Florida.

Taligoski, J., Uzun, A. and Kumar, R., “Numerical Investigation of Vortex Asymmetry on a Conical Forebody at High Angles of Incidence,” in Proceedings of the 52nd AIAA Aerospace Sciences Meeting, 13-17 January 2014, National Harbor, Maryland.

Uzun, A., Solomon, J. T., Foster, C. H., Oates, W. S., Hussaini, M. Y and Alvi, F. S., “Flow Physics of a Pulsed Microjet Actuator for High-Speed Flow Control,” AIAA Journal, Vol. 51, No. 12, December 2013, pp. 2894 – 2918.

Uzun, A., Kumar, R., Hussaini, M. Y. and Alvi, F. S., “Simulation of Tonal Noise Generation by Supersonic Impinging Jets,” AIAA Journal, Vol. 51, No. 7, July 2013, pp. 1593 – 1611.

Najafiyazdi, A., Uzun, A. and Mongeau, L. G., “On the Sources of Jet Noise: A Numerical Study Using Band-Pass Filtering,” in Proceedings of the 19th AIAA/CEAS Aeroacoustics Conference, 27-29 May 2013, Berlin, Germany.

Uzun, A. and Hussaini, M. Y., “An Application of Delayed Detached Eddy Simulation to Tandem Cylinder Flow Field Prediction,” Computers & Fluids, Vol. 60, May 2012, pp. 71 – 85.

Uzun, A. and Hussaini, M. Y., “Some Issues in Large-Eddy Simulations for Chevron Nozzle Jet Flows,” Journal of Propulsion and Power, Vol. 28, No. 2, March-April 2012, pp. 246 – 258.

Uzun, A., Bin, J. and Hussaini, M. Y., “High-Fidelity Numerical Simulation of a Chevron Nozzle Jet Flow,” International Journal of Aeroacoustics, Vol. 10, No, 5+6, October-December 2011, pp. 531 – 564.

Uzun, A. and Hussaini, M. Y., “Prediction of Noise Generated by a Round Nozzle Jet Flow Using Computational Aeroacoustics,” Journal of Computational Acoustics, Vol. 19, No. 3, September 2011, pp. 291 – 316.

Uzun, A., Kumar, R., Hussaini, M. Y. and Alvi, F. S., “Prediction of Supersonic Impinging Jet Noise Using Computational Aeroacoustics,” in Proceedings of the INTER-NOISE 2011 Conference, 4-7 September 2011, Osaka, Japan.

Uzun, A., Foster, C. H., Solomon, J. T., Oates, W. S., Hussaini, M. Y. and Alvi, F. S., “Simulations of Pulsed Actuators for High-Speed Flow Control,” in Proceedings of the 17th AIAA/CEAS Aeroacoustics Conference, 6-8 June 2011, Portland, Oregon.

Bin, J., Uzun, A. and Hussaini, M. Y., “Adaptive Mesh Redistribution Method for Domains with Complex Boundaries,” Journal of Computational Physics, Vol. 230, No. 8, April 2011, pp. 3178 – 3204.

Bin, J., Uzun, A. and Hussaini, M. Y., “Adaptive Mesh Refinement for Chevron Nozzle Jet Flows,” Computers & Fluids, Vol. 39, No. 6, June 2010, pp. 979 – 993.

Uzun, A. and Hussaini, M. Y., “Simulations of Vortex Formation Around a Blunt Wing Tip,” AIAA Journal, Vol. 48, No. 6, June 2010, pp. 1221 – 1234.

Uzun, A. and Hussaini, M. Y., “High-Fidelity Numerical Simulations of a Round Nozzle Jet Flow,” in Proceedings of the 16th AIAA/CEAS Aeroacoustics Conference, 7-9 June 2010, Stockholm, Sweden.

Zhao, H., Uzun, A., Hussaini, M. Y. and Woodruff, S. L., “Computations of Flow Past a Circular Cylinder Using a Continuous-Turbulence Model,” AIAA Journal, Vol. 47, No. 10, October 2009, pp. 2460 – 2466.

Uzun, A. and Hussaini, M. Y., “Simulation of Noise Generation in Near-Nozzle Region of a Chevron Nozzle Jet,” AIAA Journal, Vol. 47, No. 8, August 2009, pp. 1793 – 1810.

Uzun, A. and Hussaini, M. Y., “High-Fidelity Numerical Simulation of a Chevron Nozzle Jet Flow,” in Proceedings of the 15th AIAA/CEAS Aeroacoustics Conference, 11-13 May 2009, Miami, Florida.

Uzun, A., Lyrintzis, A. S. and Blaisdell, G. A., “Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction,” in Jet Aeroacoustics, edited by Ganesh Raman, published by Multi-Science Publishing Co. Ltd, 2008, pp. 95 –145.

Uzun, A. and Hussaini, M. Y., “A Computational Study on Tip Vortex Noise,” in Proceedings of the 14th AIAA/CEAS Aeroacoustics Conference, 5-7 May 2008, Vancouver, British Columbia, Canada.

Pan, F. L., Uzun, A and Lyrintzis, A. S., “Surface Integral Methods in Jet Aeroacoustics: Refraction Corrections,” Journal of Aircraft, Vol. 45, No. 2, March-April 2008, pp. 381 – 387.

Uzun, A. and Hussaini, M. Y., “Investigation of High Frequency Noise Generation in the Near Nozzle Region of a Jet using Large Eddy Simulation,” Theoretical and Computational Fluid Dynamics, Vol. 21, No. 4, July 2007, pp. 291 – 321.

Uzun, A. and Hussaini, M. Y., “Noise Generation in the Near-Nozzle Region of a Chevron Nozzle Jet Flow,” in Proceedings of the 13th AIAA/CEAS Aeroacoustics Conference, 21-23 May 2007, Rome, Italy.

Uzun, A., Hussaini, M. Y. and Streett, C. L., “Large-Eddy Simulation of a Wing Tip Vortex on Overset Grids,” AIAA Journal, Vol. 44, No. 6, June 2006, pp. 1229 – 1242.

Uzun, A., Blaisdell, G. A. and Lyrintzis, A. S., “Impact of Subgrid-Scale Models on Jet Turbulence and Noise,” AIAA Journal, Vol. 44, No. 6, June 2006, pp. 1365 – 1368.

Uzun, A. and Hussaini, M. Y., “High Frequency Noise Generation in the Near Nozzle Region of a Jet,” in Proceedings of the 12th AIAA/CEAS Aeroacoustics Conference, 8-10 May 2006, Cambridge, Massachusetts.

Lew, P., Uzun, A., Blaisdell, G. A. and Lyrintzis, A. S., “Development of a Parallel 3-D LES Methodology for Jet Aeroacoustics via the Schur Complement,” in Proceedings of the 44th AIAA Aerospace Sciences Meeting and Exhibit, 9-12 January 2006, Reno, Nevada.

Uzun, A., Hussaini, M. Y. and Streett, C. L., “Comparative Study of Single-Block vs Multiblock Jet Flow Computations,” AIAA Journal, Vol. 43, No. 5, May 2005, pp. 1143 – 1146.

Uzun, A., Hussaini, M. Y. and Streett, C. L., “Towards Tip Vortex Noise Prediction by High-Order LES on Overset Grids,” in Proceedings of the 11th AIAA/CEAS Aeroacoustics Conference, 23-25 May 2005, Monterey, California.

Uzun, A., Hussaini, M. Y. and Streett, C. L., “Progress Towards Multi-Block Large Eddy Simulations for Wind Turbine Aeroacoustics,” in Proceedings of the 43rd AIAA Aerospace Sciences Meeting and Exhibit, 10-13 January 2005, Reno, Nevada.

Xu, J., Uzun, A., Hussaini, M. Y., Kopriva, D. A. and Hardin, J. C., “Modeling and Computation of Wind Turbine Periodic Low-Frequency Noise Generation and Scattering,” in Proceedings of the 43rd AIAA Aerospace Sciences Meeting and Exhibit, 10-13 January 2005, Reno, Nevada.

Uzun, A., Blaisdell, G. A. and Lyrintzis, A. S., “Application of Compact Schemes to Large Eddy Simulation of Turbulent Jets,” Journal of Scientific Computing, Vol. 21, No. 3, December 2004, pp. 283 – 319.

Uzun, A., Lyrintzis, A. S. and Blaisdell, G. A., “Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction,” International Journal of Aeroacoustics, Vol. 3, No. 4, October 2004, pp. 297 – 346.

Pan, F. L., Uzun, A. and Lyrintzis, A. S., “Refraction Corrections for Surface Integral Methods in Jet Aeroacoustics,” in Proceedings of the 10th AIAA/CEAS Aeroacoustics Conference, 10-12 May 2004, Manchester, United Kingdom.

Uzun, A., Lyrintzis, A. S. and Blaisdell, G. A., “Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction,” in Proceedings of the 42nd AIAA Aerospace Sciences Meeting and Exhibit, 5-8 January 2004, Reno, Nevada.

Lew, P., Uzun, A., Blaisdell, G. A. and Lyrintzis, A. S., “Effects of Inflow Forcing on Jet Noise Using Large Eddy Simulation,” in Proceedings of the 42nd AIAA Aerospace Sciences Meeting and Exhibit, 5-8 January 2004, Reno, Nevada.

Uzun, A., Blaisdell, G. A. and Lyrintzis, A. S., “Sensitivity to the Smagorinsky Constant in Turbulent Jet Simulations,” AIAA Journal, Vol. 41, No. 10, October 2003, pp. 2077 – 2079.

Uzun, A., Blaisdell, G. A. and Lyrintzis, A. S., “3-D Large Eddy Simulation for Jet Aeroacoustics,” in Proceedings of the 9th AIAA/CEAS Aeroacoustics Conference, 12-14 May 2003, Hilton Head, South Carolina.

Oktay, E., Akay, H. U. and Uzun, A., “Parallelized Three-Dimensional Unstructured Euler Solver for Unsteady Aerodynamics,” Journal of Aircraft, Vol. 40, No. 2, March-April 2003, pp. 348 – 354.

Uzun, A., Blaisdell, G. A. and Lyrintzis, A. S., “Recent Progress Towards a Large Eddy Simulation Code for Jet Aeroacoustics,” in Proceedings of the 8th AIAA/CEAS Aeroacoustics Conference, 17-19 June 2002, Breckenridge, Colorado.

Oktay, E., Akay, H. U. and Uzun, A., “A Parallelized Unstructured Euler Solver for Unsteady Aerodynamics,” in Proceedings of the 40th AIAA Aerospace Sciences Meeting and Exhibit, 14-17 January 2002, Reno, Nevada.

Uzun, A., Koutsavdis, E. K., Blaisdell, G. A. and Lyrintzis, A. S., “Direct Numerical Simulation of 3-D Jets Using Compact Schemes and Spatial Filtering,” in Proceedings of the 15th AIAA Computational Fluid Dynamics Conference, 11-14 June 2001, Anaheim, California.

Lyrintzis, A. S. and Uzun, A., “Integral Techniques for Jet Aeroacoustics Calculations,” in Proceedings of the 7th AIAA/CEAS Aeroacoustics Conference, 28-30 May 2001, Maastricht, Netherlands.

Uzun, A., Akay, H. U. and Bronnenberg, C. E., “Parallel Computations of Unsteady Euler Equations on Dynamically Deforming Unstructured Grids,” in Proceedings of the Parallel CFD ’99 Conference, 24-26 May 1999, Williamsburg, Virginia.