TREX13 target experiments and case study: Comparison of aluminum cylinder data to combined finite element/physical acoustics modeling

The apparatus and experimental procedure used during the target portion of TREX13 are described. A primary goal of the TREX13 target experiments was to test the high speed modeling methods developed and previously tested as part of efforts in more controlled environments where the sediment/water interface was flat. At issue is to what extent the simplified physics used in our models can predict the changes seen in acoustic templates (target strength versus angle and frequency) as a function of grazing angle, i.e., the Target-In-the-Environment-Response (TIER), for a target proud on an unprepared “natural” sand sediment interface. Data/model comparisons for a 3 ft. long, 1 ft. diameter cylinder are used as a case study. These comparisons indicate that much of the general TIER dependence is indeed captured and allows one to understand/predict geometries where the broadest band of TIER information can be obtained. This case study indicates the predictive utility of dissecting the target physics at the expense of making the model results “inexact” from a purely finite element, constitutive equation standpoint. [Work supported by ONR and SERDP.]