Form Approved
REPORT DOCUMENTATION PAGE
OMB No. 0704-0188
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2. REPORT TYPE
1. REPORT DATE (DD-MM-YYYY)
3. DATES COVERED (From - To)
Report 2 of a series
September 2002
4. TITLE AND SUBTITLE
5a. CONTRACT NUMBER
NMLONG: Numerical Model for Simulating Longshore Current; Report 2,
5b. GRANT NUMBER
Wave-Current Interaction, Roller Modeling, and Validation of Model
Enhancements
5c. PROGRAM ELEMENT NUMBER
6. AUTHOR(S)
5d. PROJECT NUMBER
Magnus Larson, Nicholas C. Kraus
5e. TASK NUMBER
5f. WORK UNIT NUMBER
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION REPORT
NUMBER
Department of Water Resources Engineering, Lund University, Box 118, Lund,
Sweden S-22100; U.S. Army Engineer Research and Development Center, Coastal
ERDC/CHL TR-02-22
and Hydraulics Laboratory, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199
10. SPONSOR/MONITOR'S ACRONYM(S)
9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)
U.S. Army Corps of Engineers
Washington, DC 20314-1000
11. SPONSOR/MONITOR'S REPORT
NUMBER(S)
12. DISTRIBUTION / AVAILABILITY STATEMENT
Approved for public release; distribution is unlimited.
13. SUPPLEMENTARY NOTES
14. ABSTRACT
The Numerical Model of the Longshore current (NMLong) was originally developed under the U.S. Army Corps of Engineers' Dredging
Research Program. It calculates nearshore wave transformation, water level change, and wave-induced longshore current across a single beach profile,
under the assumption of longshore uniformity in both the profile and hydrodynamic processes. In considering the nearshore more generally, and the
waves at an inlet entrance in particular, both tidal and wind-generated currents can be comparable to or exceed the strength of the wave-generated
longshore current. Also, currents produced independently by waves and by wind and tide may be in opposite directions, producing complex
distributions of the current across the shore. The capability of representing the action of currents in NMLong and the interaction between the current
and waves resulted in a new model with the modified name NMLong-CW, where CW stands for the interaction between currents and waves. The new
model includes an algorithm to simulate the contribution of wave rollers generated by breaking waves, improving agreement of calculations to
measurements of the longshore current on a beach profile with a longshore bar.
This report documents the theoretical developments associated with the enhancement of NMLong that have extended it to NMLong-CW. The
new model is validated by sensitivity tests and through comparison of calculations to both field and laboratory measurements of waves and currents.
Wave transformation at a long, narrow inlet, resulting in changes in wave steepness as well as wave blocking, is described.
15. SUBJECT TERMS
See reverse.
19a. NAME OF RESPONSIBLE
16. SECURITY CLASSIFICATION OF:
17. LIMITATION
18. NUMBER
PERSON
OF ABSTRACT
OF PAGES
a. REPORT
b. ABSTRACT
c. THIS PAGE
19b. TELEPHONE NUMBER (include
area code)
85
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Standard Form 298 (Rev. 8-98)
Prescribed by ANSI Std. 239.18