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Civil and Environmental Engineering

Channel | updated April 03, 2013

The MIT Department of Civil and Environmental Engineering (CEE) is dedicated to balancing the built environment with the natural world. In our research, we seek to understand natural systems, to foster the intelligent use of resources and to design sustainable infrastructure systems.

We provide leadership in the field by focusing on technological innovations, seeking advances in basic knowledge and taking a systems perspective. We concentrate our efforts on quantitative and analytical approaches, novel experiment-based modeling, and the development and/or use of appropriate tools and technology.

CEE is an innovative and vibrant place of learning, where undergraduates, graduate students and postdoctoral researchers pursue their educational and research interests in order to lead the next generation in transforming the disciplines of civil and environmental engineering.

Our research and graduate education programs coalesce around three fields of inquiry: environmental science and engineering; mechanics, materials and structures; and transportation. We offer ABET-accredited undergraduate degree programs in civil engineering and environmental engineering science.

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1.961 - Lecture 1 - The Origin of Diffusion

1.961 - Lecture 1 - The Origin of Diffusion

1.961 Life at low Reynolds numbersIntroduction to the class Brownian motion

1.961 - Lecture 10 – Chemotaxis

1.961 - Lecture 10 – Chemotaxis

1.961 Life at low Reynolds numbersMany taxis: chemo-, photo-, pH-, magneto-, rheo-, geo-, aero-, thermo-, gyro-taxis. A computer model of chemotaxis: a sensing random walker with memory Deriving an advection-diffusion equation for bacteria

1.961 - Lecture 11 – Low Reynolds number fluid ...

1.961 - Lecture 11 – Low Reynolds number fluid dynamics (Stokes flow)

1.961 Life at low Reynolds numbersWhen inertia doesn't matter: low Reynolds number Counterintuitive fluid mechanics (GI Taylor's movie) Deriving the Stokes equations The curious phenomena of low-Reynolds number flow (GI Taylor movie)

1.961 - Lecture 12 – Properties of Stokes flow

1.961 - Lecture 12 – Properties of Stokes flow

1.961 Life at low Reynolds numbersStrouhal and Knudsen numbers A world with no inertia The instantaneous diffusion of momentum Linearity: breaking down a problem into simpler ones

1.961 - Lecture 13 – The perils of reversibility

1.961 - Lecture 13 – The perils of reversibility

1.961 Life at low Reynolds numbersParticles crossing streamlines? Solving hard problems without doing math The scallop theorem

1.961 - Lecture 14 – Stokes flow around a sphere

1.961 - Lecture 14 – Stokes flow around a sphere

1.961 Life at low Reynolds numbersDeriving the solution for the flow field The drag force on the sphere Stokes' and Whitehead's paradoxes: a low-Reynolds number fiasco

1.961 - Lecture 15 – Drag and terminal velocity

1.961 - Lecture 15 – Drag and terminal velocity

1.961 Life at low Reynolds numbers Stokes' settling speed Terminal velocity: on non-splashing mice Sinking and reproduction Non-spherical particles The anisotropy of drag: the fundamental principle of swimming at low Re An optimum shape for swimming Spines and ...

1.961 - Lecture 16 – Reorientation of organisms in a ...

1.961 - Lecture 16 – Reorientation of organisms in a flow

1.961 Life at low Reynolds numbersOrganisms exposed to shear Jeffery orbits

1.961 - Lecture 17 – Hydrodynamic signals in the ...

1.961 - Lecture 17 – Hydrodynamic signals in the plankton

1.961 Life at low Reynolds numbers The fundamental solution to Stokes' equation: the Stokeslet Other important solutions: stresslet, rotlet, potential dipole Modeling a copepod's pheromone trail The fluid mechanical signature of a sinking organism Is swimming the same ...

1.961 - Lecture 18 – Swimming at low Reynolds number

1.961 - Lecture 18 – Swimming at low Reynolds number

1.961 Life at low Reynolds numbersWhy and how to swim ? Eukaryotic flagella Prokaryotic flagella Little hairs that make a big difference: mastigonemes Cilia: coordinating many hairs

1.961 - Lecture 19 - Flagellar propulsion

1.961 - Lecture 19 - Flagellar propulsion

1.961 Life at low Reynolds numbersResistive force theory: exploiting the anisotropy of drag Optimum shape of flagella in 2D and 3D A lousy maximum swimming efficiency The energetic cost of swimming Low Reynolds number cooperation to swim faster: sperm trains

1.961 - Lecture 2 – The physics of diffusion

1.961 - Lecture 2 – The physics of diffusion

1.961 Life at low Reynolds numbersRandom walkers: a toy model for diffusion The diffusion coefficient and Einstein's formula

1.961 - Lecture 20 – Diffusion to capture

1.961 - Lecture 20 – Diffusion to capture

1.961 Life at low Reynolds numbersProbability to capture and mean time to capture Adrift at sea: mixing plankton

1.961 - Lecture 21 – Nutrient flux to osmotrophic ...

1.961 - Lecture 21 – Nutrient flux to osmotrophic organisms

1.961 Life at low Reynolds numbersThe Sherwood number Increasing the nutrient flux: an exercise in thinning your boundary layer Swimming faster to get more food Nutrient fluxes in the presence of shear or turbulence

1.961 - Lecture 22 – Particle capture

1.961 - Lecture 22 – Particle capture

1.961 Life at low Reynolds numbersHow do you capture prey at low Reynolds number ?1) Hope it diffuses to you: Brownian diffusion 2) Hope it bumps into you: interception Hair-bearing animal appendages: paddles vs. rakes

1.961 - Lecture 23 – Encounter models

1.961 - Lecture 23 – Encounter models

1.961 Life at low Reynolds numbersEncounter rate kernels Perception distance

1.961 - Lecture 24 – Finding each other in the ...

1.961 - Lecture 24 – Finding each other in the turbulent ocean

1.961 Life at low Reynolds numbersDoes turbulence help you encounter your prey or your mate? External fertilization: encounter of sperm and egg

1.961 - Lecture 3 – Diffusion around a sphere

1.961 - Lecture 3 – Diffusion around a sphere

1.961 Life at low Reynolds numbersDiffusion-limited uptake: nutrient flux to a sphere When does nutrient uptake occur only by diffusion: The Peclet number Diffusion vs. locomotion: how do you escape from your boundary layer? Diffusion and metabolism: limits to size ...

1.961 - Lecture 4 – A smooth world

1.961 - Lecture 4 – A smooth world

1.961 Life at low Reynolds numbersSolving the diffusion equation A fundamental property of diffusion: rapid smearing of fine-scale heterogeneities

1.961 - Lecture 5 – Examples and applications of ...

1.961 - Lecture 5 – Examples and applications of diffusion

1.961 Life at low Reynolds numbersThe capillary assay: testing what microorganisms like Diffusion in a pipe Insect tracheae: limits to respiration Diffusion of momentum: an analogy The porosity of eggs and the gas exchange in leaves (handouts only)