Time-Domain Simulations of Problems in Ocean Acoustics

Abstract

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the d-ataneeded, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports 10704-01881, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid DMB control number. A total-field scattered-field (TFSF) boundary can be used to introduce incident plane waves into finite-difference time-domain (FDTD) simulations. For fields which are traveling obliquely to the grid axes, there is no simple way to account fully for the effects of the inherent numerical artifacts associated with plane-wave propagation in the FDTD grid. Failure to account for these artifacts causes erroneous fields to leak across the TFSF boundary. The work performed under this grant developed a TFSF boundary for problems involving a planar interface that is theoretically exact. Such a boundary is essential when modeling the scattering from objects in the vicinity of ocean sediment. Although the TFSF boundary assumes a planar interface, the actual interface used in a simulation can take any shape and the space within the total-field region is arbitrary. A suite of C programs was written to implement the boundary. factual summary of the most significant information. PLEASE DO NOT5e. TASK NUMBER. Enter all task numbers as they 15. SUBJECT TERMS. Key words or phrases appear in the report, e.g. 05; RF0330201; T4112.identifying major concepts in the report.5f. WORK UNIT NUMBER. Enter all work unit numbers as they appear in the report, e.g. 001; 16. SECURITY CLASSIFICATION. Enter security AFAPL30480105.classification in accordance with security classification regulations, e.g. U, C, S, etc. If this form contains 6. AUTHOR(S). Enter name(s) of person(s) classified information, stamp classification level on the responsible for writing the report, performing the top and bottom of this page. research, or credited with the content of the report. The form of entry is the last name, first name, middle 17. LIMITATION OF ABSTRACT. This block must be initial, and additional qualifiers separated by commas, completed to assign a distribution limitation to the e.g. Smith, Richard, J, Jr.abstract. Enter UU (Unclassified Unlimited) or SAR (Same as Report). An entry in this block is necessary if 7. PERFORMING ORGANIZATION NAME(S) AND teasrc st elmtd the abstract is to be limited. Abstract A total-field scattered-field (TFSF) boundary can be used to introduce incident plane waves into fi...