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There is evidence that tribocharging can occur between combinations of solids, liquids and gases, for instance liquid flowing in a solid tube or an aircraft flying through air. Often static electricity is a consequence of the triboelectric effect when the charge stays on one or both of the objects and is not conducted away.
Adsorbing soap molecules make the skin negatively charged, and the slippery feeling is caused by the strongly repulsive double layer forces. [2] These forces are further relevant in many colloidal or biological systems, and may be responsible for their stability, formation of colloidal crystals, or their rheological properties.
The DL refers to two parallel layers of charge surrounding the object. The first layer, the surface charge (either positive or negative), consists of ions which are adsorbed onto the object due to chemical interactions. The second layer is composed of ions attracted to the surface charge via the Coulomb force, electrically screening the first ...
A double layer is a structure in a plasma consisting of two parallel layers of opposite electrical charge. The sheets of charge, which are not necessarily planar, produce localised excursions of electric potential, resulting in a relatively strong electric field between the layers and weaker but more extensive compensating fields outside, which restore the global potential. [1]
Stable stratifications can become unstable if layers change density. This can happen due to outside influences (for instance, if water evaporates from a freshwater lens, making it saltier and denser, or if a pot or layered beverage is heated from below, making the bottom layer less dense). However, it can also happen due to internal diffusion ...
The no-slip condition is an empirical assumption that has been useful in modelling many macroscopic experiments. It was one of three alternatives that were the subject of contention in the 19th century, with the other two being the stagnant-layer (a thin layer of stationary fluid on which the rest of the fluid flows) and the partial slip (a finite relative velocity between solid and fluid ...
Note this is valid only for one dimensional fluid flow in rectangular coordinates. The τ {\displaystyle \tau } is the shear stress at any layer of the fluid where d u / d y {\displaystyle du/dy} (i.e. the gradient of velocity in a direction perpendicular to the flow and the area of the flat plate), is the local gradient and μ {\displaystyle ...
In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake. [ 1 ] A boundary layer exists whenever there is relative movement between a fluid and a solid surface with viscous forces present in the layer of fluid close to the surface.