What is diffusion?
Fick's laws of diffusion - Wikipedia
Diffusion - Simple English Wikipedia the free encyclopedia
Confusion and diffusion - Wikipedia
Confusion and diffusion - Wikipedia
Diffusion is the net movement of anything (for example atoms ions molecules energy) from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in concentration. The concept of diffusion is widely used in many fields including physics (particle diffusion) chemistry biology sociology economics and finance (diffusion of people ideas and price values). The c…
Diffusion is the net movement of anything (for example atoms ions molecules energy) from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in concentration. The concept of diffusion is widely used in many fields including physics (particle diffusion) chemistry biology sociology economics and finance (diffusion of people ideas and price values). The central idea of diffusion however is common to all of these: a substance or collection undergoing diffusion spreads out from a point or location at which there is a higher concentration of that substance or collection. A gradient is the change in the value of a quantity for example concentration pressure or temperature with the change in another variable usually distance. A change in concentration over a distance is called a concentration gradient a change in pressure over a distance is called a pressure gradient and a change in temperature over a distance is called a temperature gradient. The word diffusion derives from the Latin word diffundere which means "to spread out." A distinguishing feature of diffusion is that it depends on particle random walk and results in mixing or mass transport without requiring directed bulk motion. Bulk motion or bulk flow is the characteristic of advection. The term convection is used to describe the combination of both transport phenomena. If a diffusion process can be described by Fick's laws it's called a normal diffusion (or Fickian diffusion); Otherwise it's called an anomalous diffusion (or non-Fickian diffusion). When talking about the extent of diffusion two length scales are used in two different scenarios: Brownian motion of an impulsive point source (for example one single spray of perfume)—the square root of the mean squared displacement from this point. In Fickian diffusion this is ${\displaystyle {\sqrt {2nDt}}}$ where ${\displaystyle n}$ is the dimension of this Brownian motion;Constant concentration source in one dimension—the diffusion length. In Fickian diffusion this is Read more on Wikipedia
"Bulk flow" is the movement/flow of an entire body due to a pressure gradient (for example water coming out of a tap). "Diffusion" is the gradual movement/dispersion of concentration within a body due to a concentration gradient with no net movement of matter. An example of a process where both bulk motion and diffusion occur is human breathing.
"Bulk flow" is the movement/flow of an entire body due to a pre...
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