Coastal regions are inherently complex, and they present intriguing scenarios for the study of fluid dynamics. An abrupt change in the aerodynamic-roughness across the land-sea intersection, the vastly different surface-thermal conditions over the land and the sea, the complex land topology, the ocean bathymetry nearshore and its effect on ocean waves all have profound effects on the local atmosphere in coastal regions. Our research group is actively studying the fluid dynamics of coastal areas via numerical simulations.
We use large-eddy simulation (LES) to simulate the flows over complex terrains to fine details which otherwise have been overlooked. We also study the interaction of ocean-bathymetry and coastal waves. The following animation shows the wind velocity variations with space and time at the Elkhorn Slough beach in Monterey Bay, California.
We also study the interaction of ocean-bathymetry and coastal waves. The following animations show the wave shoaling and breaking in simulations with the real ocean bathymetry.
Coastal waves themselves are complex and have spatially variant features that are difficult to extract using conventional data-analysis techniques widely used for spatially invariant wave field. We have recently developed a data-driven analysis framework based on the two-dimensional Hilbert-Huang transform that addresses some of the short-comings of the conventional data analysis. We have also performed high resolution phase-resolved simulations for nonlinear broadband waves propagating over coastal bathymetry. The following figures show the results from our simulations for (a) ocean surface elevation and (b) surface velocity along with (c) the bathymetry used in the simulation.
- Yang, Z., Calderer, A., He, S., Sotiropoulos, F., Krishnamurthy, R., Leo, L.S., Fernando, H.J.S., Hocut, C.M. & Shen, L. (2019), “Measurement-based numerical study of effects of realistic land topography and stratification on coastal marine atmospheric surface layer,” Boundary-Layer Meteorology, Vol. 171, pp.289-314.
- Yang, Z., Calderer, A., He, S., Sotiropoulos, F., Doyle, J., Flagg, D., MacMahan, J., Wang, Q., Haus, B., Graber, H. & Shen, L. (2018), “Numerical study on the effect of air–sea–land interaction on the atmospheric boundary layer in coastal area,” Atmosphere, Vol. 9(2), 51.