Evaluation of Baroclinic ADCIRC Using a Process-Oriented Test along a Slope

Process-oriented tests, such as those suggested by Haidvogel and Beckmann (1999), are often utilized in the validation of baroclinic processes in shallow water models. In a previous analysis, the so-called "lock-exchange" or "dam break" problem on a flat slope, wherein a vertical barrier that separates water of different densities is removed at time zero, was utilized in the validation of the baroclinic additions to the shallow water ADCIRC (ADvanced CIRCulation) model (Kolar et al., 2009). More specifically, a laboratory-scale model was utilized to capture high-resolution data sets of the lock-exchange problem. These data sets allowed for direct comparison throughout the domain of the experimental and numerical results. Results showed good agreement between model and laboratory results, sans the shear instabilities along the interface. Using these same techniques, we analyzed a density front along a slope, the "gravity adjustment" test case suggested by Haidvogel and Beckmann (1999). In this analysis, water of different densities is separated by a vertical barrier that is removed at time zero, allowing the more dense water to travel down the slope. Data is captured every 0.2 seconds using high-resolution digital photography, with salt concentration extracted by comparing pixel intensity of the dyed fluid against calibration standards. Herein, experimental results are compared to numerical results for the location of the front, along with the average root mean square errors of the salinity field.