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This result is for a specific and very simple model, but it does illustrate general features of diffusioosmoisis: 1) the hydrostatic pressure is, by definition (flow induced by pressure gradients in the bulk is a common but separate physical phenomenon) uniform in the bulk, but there is a gradient in the pressure in the interface, 2) this ...
The surface tension gradient can be caused by concentration gradient or by a temperature gradient (surface tension is a function of temperature). In simple cases, the speed of the flow u ≈ Δ γ / μ {\displaystyle u\approx \Delta \gamma /\mu } , where Δ γ {\displaystyle \Delta \gamma } is the difference in surface tension and μ ...
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 ...
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 ...
The grey represents the concentration of a molecule. A biomolecular gradient is established by a difference in the concentration of molecules in a biological system such as individual cells, groups of cells, or an entire organism. A biomolecular gradient can exist intracellularly (within a cell) or extracellularly (between groups of cells).
Diffusion is also faster in smaller, lighter molecules of which helium is the extreme example. Diffusivity of helium is 2.65 times faster than nitrogen. [14] The partial pressure gradient, also known as the concentration gradient, can be used as a model for the driving mechanism of diffusion. The partial pressure gradient is the rate of ...
This unequal distribution results in a concentration gradient that drives the dispersion of particles in the medium so that the concentration is constant across the entire bulk. With respect to convection, variations in velocity between flow paths in the bulk facilitate the distribution of the dispersed material into the medium.
A common example is surface tension gradients caused by temperature gradients. [1] Then the relevant diffusion process is that of thermal energy (heat). Another is surface gradients caused by variations in the concentration of surfactants, where the diffusion is now that of surfactant molecules.