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Welcome to Chem^ℯpediA

A resource dedicated to the teaching of transport phenomena at the University of South Florida

This site has emerged as a collaboration with students to present material in a manner that facilitates learning

Transport Phenomena Modules Microscopic balances: Transport Phenomena I Macroscopic balances: Transport Phenomena II

Introduction to Transport Phenomena Introduction to the mechanisms of transport in fluid flow Transport quantities

Microscopic balances describe velocity, temperature, and composition profiles The general microscopic balance gives point-to-point variations of a transport quantity. The following are the specialized versions of the general microscopic equation: Continuity equation Equation of motion or the Navier-Stokes equations Heat equation Convection-diffusion equation The microscopic balances are formulated with the Nabla or Del operator to simplify notation Microscopic balances are also sometimes written in terms of the material derivative Molecular fluxes are related to gradients in the transport quantities: Fick's law, Fourier's law, Newton's law of viscosity Flow rates across a boundary are determined using surface integrals

Macroscopic balances General macroscopic balance Mass balance: Describes the relationship between mass accumulation in a system with fluid flow. Momentum balance: Describes the forces on a system due to fluid flow. Total energy balance: Describes the energy accumulation in a system. This balance is rarely used as it involves both mechanical and thermal energy terms. Mechanical energy balance: A subset of the total energy balance. Describes the relationship between mechanical terms in the total energy balance (pressure, velocity, and height) in fluid flow. Internal energy balance: A subset of the total energy balance. Describes the relationship between thermal terms (temperature) and heat transfer in fluid flow.

Do you know where dimensionless numbers come from? Dimensionless numbers arise naturally in transport phenomena, and they usually represent the relative importance of forces or transport timescales. They are used to simplify microscopic and macroscopic balances. They are also used in the development of correlations for macroscopic analysis. Dimensional Analysis Buckingham-Pi Analysis

Dimensionless numbers Reynolds number Friction factor Nusselt number Prandtl number Nusselt number Schmidt number Grashof number Biot number j factor Peclet number