Robert S. Arthur

Numerical investigation of split flows by gravity currents into two‐layered stratified water bodies

The behavior of a two-dimensional (2-D) gravity current impinging upon a density step in a two-layered stratified basin is analyzed using a high-resolution Reynolds-Averaged Navier-Stokes model. The gravity current splits at the density step, and the portion of the buoyancy flux becoming an interflow is largely controlled by the vertical distribution of velocity and density within the gravity current and the magnitude of the density step between the two ambient layers. This is in agreement with recent laboratory observations. The strongest changes in the ambient density profiles occur as a result of the impingement of supercritical currents with strong density contrasts, for which a large portion of the gravity current detaches from the bottom and becomes an interflow. We characterize the current partition process in the simulated experiments using the densimetric Froude number of the current (Fr) across the density step (upstream and downstream). When underflows are formed, more supercritical currents are observed downstream of the density step compared to upstream (Fru   Frd), which indicates lower mixing between the current and ambient water after the impingement due to the significant stripping of interfacial material at the density step.

Internal Wave Breaking Dynamics and Associated Mixing in the Coastal Ocean

Introduction 548 Internal Tide Breaking 548 Classification of Internal Bores 549 Canonical bores 549 Noncanonical bores 550 Intermittency of Internal Tide Breaking 550 Internal Solitary Wave Breaking 551 Breaker Classifications 551 Mixing and Mixing Efficiency 552 A note on the internal Iribarren number 552 Mass and Sediment Transport Driven by Internal Wave Breaking 552 Summary and Outlook 553 Acknowledgments 553 References 554 Further Reading 554