Session: 11-02-03: CFD Applications for Optimization and Control II

Paper Number: 166606

Local Scale Flood Simulations and Comparisons 

The study aims to identify the optimal flood modeling tool for a local scale storm surge flood simulation. The flood modeling area is a portion of McNeese State University campus where the Contraband Bayou pass through. The bayou is connected to the Gulf of America (Mexico), and the target area is about 15 miles north of the Gulf. There are several campus buildings near the bayou, and are prone to flood if a strong storm surge reaches thus far. The simulation domain is less than a square mile, thus the simulation should be considered as local scale. The target modeling tools are HEC-RAS, Flood Modeler, and FlipFluids. HEC-RAS is the traditional hydraulic modeling tool solving the 2D depth averaged shallow water equations. There is no special treatment to implement the bayou in the simulation, which is simply implemented by the lower land elevation of the river bed compared with the elevation of the surrounding lands. On the contrary, the Flood Modeler utilize the 1D-2D coupled model to realize the bayou. The bayou flow is separately calculated with the 1D model, and a two-way coupling between the 1D model and the 2D background shallow water model. FlipFluids model is considered a CFD tool using the hybrid particle-flow method, a coupled Eulerian-Lagrangian approach. For the land elevations which is the basic geometric data for the flood modeling, a detailed LiDAR terrain mapping was conducted and the same data set was integrated in all three modeling approaches. Therefore, the results can be objectively compared to identify the differences among the models. Some hydrodynamic measurements in the bayou were also conducted to identify the initial condition of the water body. The measurements include flowrates and water depth. Since the flowrates and water depths change with the daily tidal conditions, several measurements during several day periods were conducted to identify the changes. In addition, a detail river bed profile was measured on one location of the bayou. The profile data were integrated into all three modeling tools for enhanced topographic implementation. In addition to the storm-surge flood simulation of the existing condition, a flood prevention design, flood walls, was implemented and simulated with the modeling tools for the same storm surge to investigate the effectiveness of such design. These two sets of simulation results were analyzed to identify the differences among the three modeling tools. Finally, the costs of the simulations were also compared which is also an important criterion for determining the optimal tool for this type of flood modeling.

Presenting Author: Ning Zhang McNeese State University

Presenting Author Biography: Professor of Mechanical Engineering at McNeese State University
Ph.D. Kansas State University

Authors:

Ning Zhang McNeese State University
Manoj Adhikari Kshetri McNeese State University