Viscometers and Fluids

As per your request, an investigation into the viscosity of olive oil, ketchup, and several sugar solutions was conducted. A total of 28 tests were conducted at various spindle speeds.

Viscosity can be described as the resistance to flow. When a shear stress is applied to a fluid, its layers slide past one another causing internal friction in. Viscosity is the measure of this internal friction. It is also often thought of as a fluid’s “thickness.” Highly viscous or “thick” fluids require more shear force to move than less viscous or “thin” fluids. The fundamental unit of viscosity is the poise. A material has a viscosity of one poise if it requires a shear stress of one dyne per square centimeter to produce a shear rate of one reciprocal.

At a given temerature, a fluid can be categorized based on its viscosity or flow behavior. A Newtonian fluid is a fluid that maintains a constant viscosity as the force applied to the fluid increases. The viscosity of a Newtonian fluid primarily depends on temperature and pressure. Whereas, a non-Newtonian fluid is a fluid in which the viscosity varies as the force applied to the fluid increases. A non-Newtonian fluid can be further categorized based on the way its viscosity changes in response to variations in shear rate. Two common types of non-Newtonian fluids are pseudoplastic and dilatent. A fluid classified as pseudoplastic demonstrates shear thinning, which is when a fluid’s viscosity decreases as the applied force increases. A fluid classified as dilatent demonstrates shear thickening, which is when a fluid’s viscosity increases as the applied force increases. As almost all fluids increase in temperature, the viscosity of the fluid decreases. Milk, gelatin, blood, and ketchup all exhibit shear thinning; while, cytoplasm, wet sand, silly putty, and concentrated sugar water solutions all exhibit shear thickening. Requardless of what category a particular fluid falls in, as temperature increases, all materials will show an increase in flow, thus a decrease in viscosity.

Newton’s Law of Viscosity states that the ratio of a shear stress to the shear rate (the velocity gradient that it produces) equals a fluid’s resistance to permenent deformation, which is its viscosity. Newtonian fluids its shear stress is linearly proportional to the velocity gradient in the direction perpendicular to the plane of shear. The constant of proportionality is known as the viscosity. These relationships can also be observed on a shear stress vs strain rate graph. (See Figure 1)

Understanding how various environmental factors affect a material’s viscosity is extremely important in the scientific world……The human body reacts differently to different fluids, so the right one can be vital

Brookfield