Lecture

Understanding Water and Viscosity

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In course

PHYS-468: Physics of life

Life has emerged on our planet from physical principles such as molecular self-organization, thermodynamics, stochastics and iterative refinement. This course will introduce the physical methods to study life and will discuss the quantitative and physical ...

Description

This lecture delves into the fascinating properties of water, such as its phase transitions, surface tension, and complex behavior in different conditions. The discussion covers the structure of water, its phase diagram, and the concept of viscosity, including the Arrhenius relationship. The lecture also explores the intriguing world of non-Newtonian fluids, using ketchup as an example, and how its viscosity changes under different forces. Additionally, the talk touches on the innovative technology of surface coatings that can manipulate fluid behavior, offering insights into the intricate nature of fluid dynamics and its practical applications.

Instructor

Henning Paul-Julius Stahlberg

Mission We use high-resolution cryo-electron microscopy to study neurodegeneration and other protein systems. We also develop novel imaging technology in the areas of electron microscopy hardware and applications, sample preparation, data collection schemes, and data analysis software systems. The Stahlberg group is supported by the University of Lausanne, Faculty of Medicine and Biology, and by the EPFL, Faculty of Basic Sciences, Physics Institute. The LBEM is a research laboratory of both UNIL and EPFL.

Official source

Ontological neighbourhood

Physics

Mechanics: Fluid mechanics

Related concepts (25)

Fluid mechanics

Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasmas) and the forces on them. It has applications in a wide range of disciplines, including mechanical, aerospace, civil, chemical, and biomedical engineering, as well as geophysics, oceanography, meteorology, astrophysics, and biology. It can be divided into fluid statics, the study of fluids at rest; and fluid dynamics, the study of the effect of forces on fluid motion.

Non-Newtonian fluid

A non-Newtonian fluid is a fluid that does not follow Newton's law of viscosity, that is, it has variable viscosity dependent on stress. In non-Newtonian fluids, viscosity can change when under force to either more liquid or more solid. Ketchup, for example, becomes runnier when shaken and is thus a non-Newtonian fluid. Many salt solutions and molten polymers are , as are many commonly found substances such as custard, toothpaste, starch suspensions, corn starch, paint, blood, melted butter, and shampoo.

Fluid dynamics

In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation.

Newtonian fluid

A Newtonian fluid is a fluid in which the viscous stresses arising from its flow are at every point linearly correlated to the local strain rate — the rate of change of its deformation over time. Stresses are proportional to the rate of change of the fluid's velocity vector. A fluid is Newtonian only if the tensors that describe the viscous stress and the strain rate are related by a constant viscosity tensor that does not depend on the stress state and velocity of the flow.

Power-law fluid

NOTOC In continuum mechanics, a power-law fluid, or the Ostwald–de Waele relationship, is a type of generalized Newtonian fluid (time-independent non-Newtonian fluid) for which the shear stress, τ, is given by where: K is the flow consistency index (SI units Pa sn), ∂u/∂y is the shear rate or the velocity gradient perpendicular to the plane of shear (SI unit s−1), and n is the flow behavior index (dimensionless). The quantity represents an apparent or effective viscosity as a function of the shear rate (SI unit Pa s).

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