Understanding turbulence for better flow prediction and control Junlin Yuan Lee & Li 13, NASA/JPL Favier et al. JFM 09 Thank you for the introduction. I am going to talke about combined effects of roughness and acce in bounary layers. This is a colaboration with ugo piomelli from Queens’ ---- P24: add: uv+ profiles Questions what’s the link with RANS models Variation of turbulent statistics How to calculate tauw Start with link with other talks? Add publication in cite ME Retreat, Aug. 22, 2016

Design / analysis / control Resolving physics Outline Fundamental studies Modeling techniques Design / analysis / control Integrating important mechanisms; Calibration database West & Yuan, 2016 Smooth Rough Simulating complex flows using models

Fundamental studies Objective Approaches Acceleration + Deceleration Fundamental studies Objective Turbulence response to disturbances? Coupling mechanisms? Roughness, pressure gradients, curvature, unsteadiness, rotation, transition, … Approaches Problem simplification Resolved simulation Manipulation of flow/boundary conditions Yuan & Piomelli, PoF, 2013 Mottaghian, PhD thesis, 2015 Mesh Yuan & Piomelli, JoT, 2014

Important role of roughness topography Fundamental studies (a) Low turbulent time scale (b) High turbulent time scale Eddy Acceleration Wake production Enhanced isotropy Roughness wake Results Turbulence production & redistribution mechanisms Physics-based parameterization of topography Important role of roughness topography Sand grains Turbine roughness

Hope for a universal correlation! Modeling Negative wake field Physics-based Hope for a universal correlation! Friction Integrating physics in one-point turbulent closures Geometry-based Friction

Design/analysis/control Analysis of hydraulic turbine performance Roughness model calibration Accurate loss estimation Design of vertical-axis wind turbine Power output calculation Angle-of-attack optimization Interested in other fluid-related problems Non-equilibrium, unsteady, complex geometry, .. Yuan et al., IOP Conf. Series 2014