Development and Implementation of Depth Dependent Wave Forcing and Stokes Drift into Coupled 3D PADCIRC/PUNSWAN Joshua Todd Coastal Engineering Department of Marine and Environmental Systems Florida Institute of Technology Advisor: Dr. Robert Weaver April 29,2013

Objective To modify the three dimensional version of ADCIRC to use wave forcing and mass flux in the calculation of sea surface elevation and current velocities

Background Stokes 1847 – Study of Water Waves Longuet-Higgins and Stewart 1962 – Studied shoreward directed momentum flux by water waves Mellor 2003,2008 – Included wave effects on three dimensional equations of motion in addition to the LHS radiation stress

Modifications Add three dimensional depth dependent radiation stress to the momentum equations Add depth dependent Stoke’s drift to the velocity solution

Mellor 2008

Stokes Drift Incorporates mass transport from waves into the 3D model

SWAN Coupling Uses SWAN to provide: – Wave Number – Direction – Frequency – Energy (from the Action Density)

Couple2Swan Added 3D Radiation Stress equation to the ComputeRadiationStress and ComputeWaveDrivenForces Subroutines Created Compute3DStokesDrift Subroutine Set up equations to be able to turn them on and off with Input File Flags

VSMY Added Stoke’s Drift Velocity to the velocity at each node Added the 3D Radiation Stress to the RHS forcing vector in the VSSOL subroutine

IM Types 3 Different Models – IM 7 - Depth Dependent Radiation Stress – IM 8- Depth Dependent Radiation Stress and Stokes Drift – IM 9- Stokes Drift

Stability Testing Hurricane Gustav – EC95 Grid – Quick Run – No Tides – 5 day run Results Pending

Questions?