Diffusion in Fluid Mechanics

This lecture introduces the concept of diffusion in fluid mechanics, explaining how molecules and small particles transport in a fluid without flow. The instructor discusses the properties of diffusion, the diffusion equation, and the relationship between diffusion and fluid flow. By using a model of random walk on a 1D lattice, the lecture derives the convection-diffusion equation and explains the physical meaning behind it. The lecture also explores the microscopic description of diffusion, the diffusion equation in 3D, and how to estimate diffusion coefficients. Through a practical example with water molecules, the lecture demonstrates how theoretical predictions align with experimental results.