Fluid Dynamics Research Facility
Professor Dana Dabiri
Researchers:
Mazyar Amin (M.S./Ph.D., AA), Greg Rixon (Ph.D., AA), Wei-Hsin Tien (Ph.D., AA), Fletcher Kimura (Ph.D., Chemistry), Rob Grothe (M.S. AA), and Joey Duncan (M.S., AA), and Alvaro Pantigoso (M.S., AA)
- Development and Implementation of Advanced Fluid Imaging Diagnosticss
- Three-Dimensional Experimental Investigations of LES Turbulence Models
- Vertical Display Case Air Curtain Optimization
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 Free surface deformation due to a vertical shear layer intersecting with a free surface Click on image for full size. |
Development and Implementation of Advanced Fluid Imaging Diagnosticss
DDPIV: In the last couple of decades, the development of Digital Particle Image Velocimetry (DPIV) has allowed for spatial and temporal measurements by providing two-component velocities within a plane through time. Most recently, Defocusing Digital Particle Image Velocimetry (DDPIV) has allowed for complete spatial and temporal measurements by providing three-component velocities within a volume. To further develop this methodology, we have derived A Full Three-Dimensional Characterization of Defocusing Digital Particle Image Velocimetry Furthermore, we have overcome the limitations of previous implementations of the single camera DDPIV system, which could only image sparsely distributed particles, by developing A color-coded backlighted defocusing digital particle image velocimetry system.
Outlier Detection and Correction: We propose a new method for correcting spurious displacement vectors obtained by using particle image velocimetry. Unlike methods that generate and use statistics from neighboring vectors toward outlier identification, a bootstrapping process is employed to generate statistics for each component. The mode-ratio criterion, defined as the normalized absolute value of the difference between the mode of the generated statistics and the actual value on the field, is used to identify and tag spurious components. The bootstrapping process is repeated to generate new statistics from the untagged components. This process is then repeated multiple times. The resulting mode field is used as the correction field. The method is then tested on a real turbulent jet flow, obtained from www.pivchallenge.org.
The field on the left is obtained by performing a basic cross-correlation algorithm on a pair of experimentally obtained PIV images of a turbulent jet flow, available at the PIV challenge website, www.pivchallenge.org. Note that the vector field contains both random and clustered errors. The plot to the right shows the outlier-corrected result using the mode-ratio bootstrapping method. Note that the random errors shown in region 1, the small clustered error shown in region 2, and the large clustered error sown in region 3 are well identified and corrected. For further reference, please see Mode-ratio bootstrapping method for PIV outlier correction.
Three-Dimensional Experimental Investigations of LES Turbulence Models
The goal of this project is to perform three-dimensional experimental studies of turbulent flow over a heated backward-facing step using novel experimental diagnostics. Towards this end, we propose to combine Defocusing Digital Particle Image Velocimetry (DDPIV) with Digital Particle Image and Thermometry Velocimetry (DPITV) to allow for measurements of temperature and velocity simultaneously, within a volume, a technique which we refer to as Defocusing Digital Liquid Crystal Particle Thermometry and Velocimetry (DDLCPTV). Upon completion of the development of this method, we will investigate LES turbulence models, and perhaps develop more accurate and generally applicable models for numerical simulation based on a deeper understanding of the flow physics. (see NSF 2005 Nugget and NSF 2006 Nugget and NSF 2007 Nuggetand NSF 2008 Nugget.)
Vertical Display Case Air Curtain Optimization
This collaborative effort between UW, Kettering University, and Southern California Edison, is to study air curtains, their entrainments, and their infiltration as applied to vertical open display cases, which are commonly found in supermarket stores nationwide. The goal is to ascertain the conditions that would minimize ambient warm air infiltration into the vertical display cases, so as to minimize the energy consumption of the display cases. As vertical display cases are used nationwide, we will therefore be able to reduce the national energy burden in this area. Also see this article.
