Abstract
The Computation and Modeling Engineering Laboratory (CaMEL), an implicit solver-based storm surge model, has been extended for use on high performance computing platforms. An MPI (Message Passing Interface) based parallel version of CaMEL has been developed from the previously existing serial version. CaMEL uses hybrid finite element and finite volume techniques to solve shallow water conservation equations in either a Cartesian or a spherical coordinate system and includes hurricane-induced wind stress and pressure, bottom friction, the Coriolis effect, and tidal forcing. Both semi-implicit and fully-implicit time stepping formulations are available. Once the parallel implementation is properly validated, CaMEL is evaluated against ADCIRC, an established storm surge model, using a hindcast of storm surge due to Hurricane Katrina. Observed high water marks are used to verify that both models have comparable accuracy. The effects of time step on the stability and accuracy of the models are investigated and indicate that the semi- and fully-implicit solvers in CaMEL allow the use of larger timesteps than ADCIRC’s explicit and semi-implicit solvers. However, ADCIRC outperforms CaMEL in parallel scalability and execution wall clock times. Wall times of CaMEL improve significantly when the largest stable time step sizes are used in respective models, although ADCIRC still is faster.
Highlights
The destruction caused by frequent hurricanes in the recent past calls for a reliable and fast storm surge model capable of predicting storm surges, floods, and levee overtopping phenomena
The Computation and Modeling Engineering Laboratory—Shallow Water Equation program is a recently developed storm surge model [8,16] that uses an implicit solver, primarily developed with the capability to use larger time step sizes with great numerical stability
The explicit solver option of Advanced Circulation (ADCIRC) appears to perform better than its semi-implicit solver or Computation and Modeling Engineering Laboratory (CaMEL)’s fully implicit
Summary
The destruction caused by frequent hurricanes in the recent past calls for a reliable and fast storm surge model capable of predicting storm surges, floods, and levee overtopping phenomena. The Computation and Modeling Engineering Laboratory—Shallow Water Equation program (referred to as CaMELSWE or CaMEL from here after) is a recently developed storm surge model [8,16] that uses an implicit solver, primarily developed with the capability to use larger time step sizes with great numerical stability. ADCIRC GWCE utilizes a three time-level semi-implicit scheme centered at k (i.e., the present time level), and the momentum equation uses a two time-level scheme centered at k + 1/2 They proved that the implicit treatment of the non-linear terms through the use of a time-marching algorithm stabilizes the solution. In the semi-implicit formulation of the ADCIRC momentum equation, barotropic pressure gradients, Coriolis, free surface stresses, and bottom friction terms are ‘averaged’ between the new time step values and previous time step values. The rest of the paper is organized as follows: Section 2 presents governing equations, Section 3 presents the CaMEL model approach, Section 4 briefly presents the ADCIRC model approach, Section 5 presents the CaMEL parallel implementation, Section 6 presents the benchmarking of the CaMEL parallelization, Section 7 presents a model comparison using the hurricane storm surge hindcast, Section 8 presents model execution and parallel scalability, and Section 9 presents concluding remarks
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