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Some particles are dissolved in a glass of water. At first, the particles are all near one top corner of the glass. If the particles randomly move around ("diffuse") in the water, they eventually become distributed randomly and uniformly from an area of high concentration to an area of low, and organized (diffusion continues, but with no net flux).
Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size (mass) of the particles.
2-dimensional random walk of a silver adatom on an Ag(111) surface [1] Simulation of the Brownian motion of a large particle, analogous to a dust particle, that collides with a large set of smaller particles, analogous to molecules of a gas, which move with different velocities in different random directions.
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
Water particles (blue) and larger virus particle (red). The impact between the virus and water molecules will cause translational and rotational movement with varying speeds depending on the angle and speed of impact. Let's say there is a virus which can be modelled as a perfect sphere with the following conditions:
The process of osmosis over a semipermeable membrane.The blue dots represent particles driving the osmotic gradient. Osmosis (/ ɒ z ˈ m oʊ s ɪ s /, US also / ɒ s-/) [1] is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential ...
where is the gravitational constant; is the density of the sediment; is the density of water; is the sediment particle diameter (commonly assumed to be the median particle diameter, often referred to as in field studies); and is the molecular viscosity of water. The Stokes settling velocity can be thought of as the terminal velocity resulting ...
In physics and engineering, permeation (also called imbuing) is the penetration of a permeate (a fluid such as a liquid, gas, or vapor) through a solid.It is directly related to the concentration gradient of the permeate, a material's intrinsic permeability, and the materials' mass diffusivity. [1]