NOTE: Later starting time than usual.

36th NIA CFD Seminar

Topic: Improved Turbulence and Transition Modeling Methods for Industrial CFD Simulations

[ There will be a brief overview by Dr. Baeder of the CFD research activities in the Dept. of Aerospace Engineering at the University of Maryland College Park. ]

Date: Tuesday, June 11, 2013

Time:11:30am-12:30pm (EST),

Location: NIA room 137

Speaker: Shivaji Medida

Biography: Shivaji Medida is a Ph.D. candidate in the Dept. of Aerospace Engineering at the University of Maryland College Park. He received a Master of Science degree in Mechanical Engineering from The University of Toledo in 2007, with a focus on developing high­-order accurate non­reflecting boundary conditions for computational aeroacoustics simulations. He received a Bachelor of Technology degree in Aerospace Engineering from the Indian Institute of Technology Madras in 2005. His doctoral research is focused on improving turbulence and transition modeling methods for unsteady RANS simulations of fixed-­wing and rotorcraft/wind­-turbine applications. His research interests include RANS and hybrid RANS­LES turbulence modeling, high­-order numerical schemes for PDEs, and high performance computing.

Abstract: Without significant enhancements to traditional RANS turbulence models, it is difficult to predict viscous flow phenomena such as laminar-­turbulent boundary layer transition, and flow reversal/separation in wall-­bounded flows. These modifications are necessary to improve skin friction drag and stall onset predictions in high­Reynolds number flows at an affordable computational cost without resorting to expensive methods such as DNS/LES and other hybrid methods. In this work, the correlation­based intermittency ­transport transition model of Langtry&Menter is improved, and coupled with the one­-equation Spalart-­Allmaras turbulence model. Transition onset and drag predictions obtained using the improved transition model coupled with the k-­omega SST model and the S­A model agree well with experimental data for various 2-­D flat plate and airfoil cases. A new crossflow transition onset criterion is developed to account for crossflow instabilities in 3-­D boundary layers. Significant improvement in transition onset prediction, compared to the baseline transition model, is demonstrated on 3­-D fixed wing and rotorcraft problems using the new crossflow criterion. Next, a new empirical criterion is identified and applied to RANS turbulence models to increase their sensitivity to strong adverse pressure gradients (APG) that lead to flow reversal and separation of boundary layers. Improved static and dynamic stall predictions on 2-­D airfoils are demonstrated with APG-­sensitive turbulence modeling.

Additional information, including the webcast link, can be found at the NIA CFD Seminar website, which is temporarily located at

http://www.hiroakinishikawa.com/niacfds/