Lecture 1: Fluid Dynamics

MIT RES.12-003 Fluid Motions, Sediment Transport, and Current-Generated Sedimentary Structures, Fall 2025 Instructor: John Southard View the complete course: https://ocw.mit.edu/courses/res-12-003-fluid-motions-sediment-transport-and-current-generated-sedimentary-structures-fall-2025/ YouTube Playlist: https://www.youtube.com/playlist?list=PLUl4u3cNGP60q1Ib4pyz_FBs_lYUPr9MN This lecture introduces the fundamentals of fluid dynamics as they relate to sediment transport in natural environments like rivers and oceans. Prof. Southard explains key concepts such as laminar versus turbulent flow, Reynolds number, and dimensional analysis, using classic experiments to illustrate how fluid behavior changes with velocity. The discussion then expands to forces acting on particles, including drag, lift, and the role of viscosity, as well as how flow interacts with boundaries in channels. The lecture also explores oscillatory flows generated by waves, their effects on sediment movement, and how combined flow conditions can become complex. Finally, it examines how sediment begins to move, highlighting factors like shear stress, particle size, and turbulence, and introduces concepts such as the Shields diagram to describe the onset of motion. License: Creative Commons BY-NC-SA More information at https://ocw.mit.edu/terms More courses at https://ocw.mit.edu Support OCW at http://ow.ly/a1If50zVRlQ We encourage constructive comments and discussion on OCW’s YouTube and other social media channels. Personal attacks, hate speech, trolling, and inappropriate comments are not allowed and may be removed. More details at https://ocw.mit.edu/comments.