Bird, Stewart & Lightfoot 2025, p > 자유게시판

• 목록
• 답변
• 글쓰기
• 게시판 리스트 옵션
  • 수정
  • 삭제

Viscosity is a measure of a fluid's fee-dependent resistance to a change in form or to movement of its neighboring portions relative to each other. For liquids, heavy duty pruning shears it corresponds to the informal idea of thickness; for Wood Ranger Power Shears website example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a power shears multiplied by a time divided by an area. Thus its SI models are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal frictional drive between adjacent layers of fluid that are in relative movement. As an illustration, when a viscous fluid is compelled by means of a tube, it flows extra shortly close to the tube's heart line than near its walls. Experiments present that some stress (comparable to a strain difference between the 2 ends of the tube) is required to maintain the movement. It is because a force is required to overcome the friction between the layers of the fluid which are in relative movement. For a tube with a constant charge of circulate, the energy of the compensating force is proportional to the fluid's viscosity.

Normally, viscosity relies on a fluid's state, corresponding to its temperature, Wood Ranger Power Shears website strain, and price of deformation. However, the dependence on a few of these properties is negligible in certain instances. For instance, the viscosity of a Newtonian fluid doesn't fluctuate considerably with the speed of deformation. Zero viscosity (no resistance to shear stress) is noticed only at very low temperatures in superfluids; otherwise, the second legislation of thermodynamics requires all fluids to have optimistic viscosity. A fluid that has zero viscosity (non-viscous) known as perfect or inviscid. For non-Newtonian fluids' viscosity, there are pseudoplastic, plastic, and dilatant flows which are time-impartial, and there are thixotropic and rheopectic flows which might be time-dependent. The word "viscosity" is derived from the Latin viscum ("mistletoe"). Viscum additionally referred to a viscous glue derived from mistletoe berries. In materials science and engineering, there is usually interest in understanding the forces or stresses concerned in the deformation of a fabric.

For example, if the material had been a simple spring, the answer could be given by Hooke's law, Wood Ranger Power Shears shop which says that the pressure skilled by a spring is proportional to the distance displaced from equilibrium. Stresses which can be attributed to the deformation of a fabric from some relaxation state are known as elastic stresses. In different materials, stresses are present which could be attributed to the deformation rate over time. These are known as viscous stresses. For instance, in a fluid similar to water the stresses which come up from shearing the fluid do not rely upon the distance the fluid has been sheared; reasonably, they depend upon how shortly the shearing occurs. Viscosity is the material property which relates the viscous stresses in a fabric to the speed of change of a deformation (the strain charge). Although it applies to normal flows, Wood Ranger Power Shears website it is straightforward to visualize and define in a simple shearing flow, such as a planar Couette stream. Each layer of fluid moves quicker than the one just under it, Wood Ranger Power Shears order now and friction between them provides rise to a Wood Ranger Power Shears manual resisting their relative movement.

Particularly, the fluid applies on the top plate a force within the direction opposite to its motion, and an equal but reverse force on the bottom plate. An external Wood Ranger Power Shears website is therefore required so as to maintain the top plate moving at constant speed. The proportionality factor is the dynamic viscosity of the fluid, often simply referred to as the viscosity. It is denoted by the Greek letter mu (μ). This expression is known as Newton's law of viscosity. It is a special case of the overall definition of viscosity (see beneath), which will be expressed in coordinate-free form. In fluid dynamics, Wood Ranger Power Shears website it is sometimes more acceptable to work in terms of kinematic viscosity (generally also called the momentum diffusivity), defined because the ratio of the dynamic viscosity (μ) over the density of the fluid (ρ). In very general terms, Wood Ranger Power Shears website the viscous stresses in a fluid are defined as these ensuing from the relative velocity of various fluid particles.