4:10-4:35 p.m. Presentation
“A Novel Particle Tracking Technique using a Scanning Laser Setup Tested via Numerical Experiment”
Presented by MELISSA KOZUL from NTNU (Host: Prof. Tamer Zaki)
Lagrangian particle tracking relying on line-of-sight based volumetric methods is challenged by high particle densities, required for the adequate spatial resolution of high Reynolds-number flows. This presentation will introduce a novel robust 3D particle tracking technique based on a scanning laser setup. We have developed an effective triangulation greatly reducing ghost particle reconstruction using images from only two cameras. Following successful reconstruction of a time series of 3D particle fields, Lagrangian velocities and accelerations are calculated using particle tracking. The method was developed via numerical experiment using the Johns Hopkins Turbulence Database.
4:35-5:00 p.m. Presentation
“Scale Separation in Restricted Nonlinear Wall-Bounded Turbulence”
Presented by BENJAMIN MINNICK (Adviser: Prof. Dennice Gayme)
Numerical and experimental studies have revealed the significance of streamwise coherent structures in wall-bounded turbulence, both near the wall where energy is dissipated and far from the wall where energy is carried. Engineering applications have prompted the study of wall-bounded turbulent flows however, the computational expense of resolving the necessary scales has limited our ability to interrogate the mechanisms underlying the flow. Recently the restricted nonlinear (RNL) model has been proposed. Motivated by these streamwise coherent structures inherent in wall-bounded turbulence, the RNL model neglects nonlinear interactions between nonzero streamwise Fourier modes thereby reducing the order of the streamwise varying dynamics. At low Reynolds number, the RNL model has been shown to accurately predict first-and second-order statistics while retaining as few as one nonzero Fourier mode. Extending to more moderate Reynolds numbers, this model correctly captures log-law behavior, provided the streamwise dynamics are band-limited to dissipative scales. In this work, we move the RNL modeling paradigm to even higher Reynolds numbers, in a regime where a separation of scales is expected. We present results of current efforts and identity additional phenomena to properly capture scale separation.