Research Themes

  • Numerical methods for fluid mechanics

    I have been developing immersed boundary (IB) methods to simulate turbulent flows in a Reynolds-Averaged Navier-Stokes context with application complex, industrial problems during my PhD thesis ( more ). This research led to the introduction of novel IB conditions based on turbulent wall-models ( more ) and adaptive grids ( more ). More recently we have explored the use of IB for conjugate heat transfer problems ( more ) and for aero-acoustics applications ( more ). The methods that I developed are routinely used in industry for design studies ( more ). I also wrote a review article ( more ) on IB methods (with Prof. R. Mittal) that is one of the most cited (10th) and downloaded (7th) papers in Annual Review of Fluid Mechanics ( see ).
  • Physical models for laminar/turbulent flows

    The development of models for turbulent flows has been the original theme that attracted me to Stanford. I worked with Prof. P. Durbin on a variety of problems involving the V2F model: heat transfer ( more ), separation ( more ), unsteady effects ( more ). I developed V2F implementations for commercial codes ( more ) that are now used by 100s of engineers worldwide. More recently we have developed an anisotropic eddy diffusion model based on the V2F framework ( more ). We have also studied transition to turbulence in high-speed flows using DNS ( more ), and more recently applying uncertainty quantification techniques ( more ). I have also been involved in a detailed investigation of the effect of non-Newtonian stresses in turbulent and transitional flows. I have developed a Reynolds-averaged model for polymer solutions ( more ) and we have used DNS to study the transition characteristics of the wake of a cylinder in the presence of polymer injection ( more ).

    Uncertainty Quantification in Computational Science

    This is the most recent focus of my research. I have been leading the uncertainty modeling in the DoE PSAAP Center at Stanford. Our focus is on high-speed reactive flows and we have developed new techniques to handle highly non-linear system responses driven by shocks ( more ), problems with large number of uncertainties induced by imprecise reaction rates ( more ), and extended existing techniques to solve genuinely hyperbolic systems ( more ). An important area of research is the assessment of uncertainties induced by assumptions in physical model, for example turbulence ( more ) or mixing. More recently I have been interested in optimization under uncertainty ( more ).

Predictive Science Academic Alliance Program (PSAAP)

Simulations of hypersonic air-breathing propulsion vehicle, the HyShot system. Simulations are based on RANS modeling and include both reacting and non-reacting computations. ness element.

Uncertainty Quantification in Reacting Flows

Uncertainty in the prediction of CO concentration for Sandia Flame D induced by imperfect measerements of the reaction rates.

Modeling and simulations of scalar dispersion in urban environments (Completed)

Simulations of dispersion scenarios in downtown Chicago. Under the same wind conditions, few hundred feet displacement of the release source can lead to large differences in the downstream dispersion.

Fluid Mechanics of Formula 1 Tires (Completed)

Simulations of the turbulent flow around a realistic Formula 1 tire. The contours show pressure distributions on an horizontal plane close to the ground to illustrate the vortical structures.

Effect of roughness in hypersonic boundary layers (Completed)

Simulations of high-speed boundary layer on a flat plate with a discrete roughness element. The picture shows contours of density to identify the edge of the boundary layer and a weak compression shock downstream of the roughness element.