In physics, chemistry, biology and engineering, a transport phenomenon is any of various mechanisms by which particles or quantities move from one place to another. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties Foundations of modern biology There are five unifying principles Engineering is the Discipline and Profession of applying technical and scientific Knowledge and A physical Quantity is a physical property that can be quantified The laws which govern transport connect a flux with a "motive force". In the various subfields of Physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks In Physics, a force is whatever can cause an object with Mass to Accelerate. Three common examples of transport phenomena are diffusion, convection, and radiation. Diffusion is the net movement of particles (typically molecules from an area of high concentration to an area of low concentration by uncoordinated random movement Convection in the most general terms refers to the movement of molecules within Fluids (i Radiant energy is the Energy of Electromagnetic waves The quantity of radiant energy may be calculated by integrating Radiant flux (or power The science of trasport phenomena is a great compliment to rheological study of Newtonian fluids. A Newtonian fluid (named for Isaac Newton) is a Fluid whose stress versus rate of strain curve is linear and passes through the origin
There are three main categories of transport phenomena:
- Heat transfer,
- Mass transfer, and
- Fluid dynamics (or momentum transfer)
An important principle in the study of transport phenomena is analogy between phenomena. In thermal physics, heat transfer is the passage of Thermal energy from a hot to a colder body Mass transfer is the phrase commonly used in engineering for physical processes that involve molecular and convective transport of Atoms and Molecules Fluid dynamics is the sub-discipline of Fluid mechanics dealing with fluid flow: Fluids ( Liquids and Gases in motion For example, mass, energy, and momentum can all be transported by diffusion:
- The spreading and dissipation of odors in air is an example of mass diffusion. Diffusion is the net movement of particles (typically molecules from an area of high concentration to an area of low concentration by uncoordinated random movement
- The conduction of heat in a solid material is an example of heat diffusion. The heat equation is an important Partial differential equation which describes the distribution of Heat (or variation in temperature in a given region over time
- The drag (physics) experienced by a rain drop as it falls in the atmosphere is an example of momentum diffusion (the rain drop loses momentum to the surrounding air through viscous stresses and decelerates). In Fluid dynamics, drag (sometimes called fluid resistance) is the force that resists the movement of a Solid object through a Fluid (a Momentum diffusion refers to the Diffusion, or spread of Momentum between particles ( Atoms or Molecules of Matter, usually in the
The transport of mass, energy, and momentum can also be affected by the presence of external sources:
- An odor dissipates more slowly when the source of the odor remains present.
- The rate of cooling of a solid that is conducting heat depends on whether a heat source is applied.
- The gravitational force acting on a rain drop counteracts the drag imparted by the surrounding air.
All these effects are described by the generic scalar transport equation. The generic scalar transport equation is a general Partial differential equation that describes Transport phenomena such as Heat transfer, Mass transfer
The generalised method adopted for solving trasport phenomena problems start with quantity analysis for any given system as:
(Rate of quantity IN) - (Rate of quantity OUT) + (Rate of Production of the quantity) = (Rate of Accumulation of the Quantity)
The transfering quantity here can be momentum, energy or mass. For example, during momentum transport analysis for a freely falling film of a Newtonian liquid, gravitational force is counted as a factor increasing momemtum in the system; and the momentum dissipation will be in the form of fluid moving out of the system, and work losses. [1]
The same equations governing convection in heat transfer can be applied to convection in mass transfer. When studying complex transport phenomena problems one must use tools from continuum mechanics and tensor calculus and often problems can be expressed as partial differential equations. Continuum mechanics is a branch of Mechanics that deals with the analysis of the Kinematics and mechanical behavior of materials modeled as a continuum e History The word tensor was introduced in 1846 by William Rowan Hamilton to describe the norm operation in a certain type of algebraic system (eventually In Mathematics, partial differential equations ( PDE) are a type of Differential equation, i
In solid state physics, the motion and interaction of electrons, holes and phonons are studied under "transport phenomena". Solid-state physics, the largest branch of Condensed matter physics, is the study of rigid Matter, or Solids The bulk of solid-state physics theory and [2]
Contents |
See also
Resources
- Some Classical Transport Phenomena Problems with Solutions - Fluid Mechanics. In Structural analysis, constitutive relations connect applied stresses or Forces to strains or Deformations The constitutive relation A continuity equation is a Differential equation that describes the conservative transport of some kind of quantity Wave propagation is any of the ways in which waves travel through a Waveguide. In Medicine, a person's pulse is the throbbing of their arteries. In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal
- Some Classical Transport Phenomena Problems with Solutions - Heat Transfer.
- Some Classical Transport Phenomena Problems with Solutions - Mass Transfer.
External links
- Transport Phenomena Archive in the Teaching Archives of the Materials Digital Library Pathway
References
- ^ R. Byron Bird, Warren E. Stewart, Edwin N. Lightfoot, Transport Phenomena (1960) John Wiley & Sons, New York, ISBN 0-471-07392-X, pp. The first edition of Transport Phenomena was published in 1960 two years after having been preliminarily published under the title Notes on Transport Phenomena based 42-48
- ^ J. M. Ziman, Electrons and Phonons: The Theory of Transport Phenomena in Solids (Oxford Classic Texts in the Physical Sciences)
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