# What is Mastering Fluid Dynamics

Mastering Fluid Dynamics is a field that encompasses several practical disciplines, such as aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). It offers a systematic structure to scientifically understand fluid flow by embracing empirical and semi-empirical laws derived from experimental measurement and applied in solving real problems.

#### Viscosity and Centipoise

One of the most important concepts to master in fluid dynamics is dynamic viscosity. The more viscous a fluid is, the slower it will move when a shear force is applied. The dynamic viscosity of a fluid is proportional to the shear rate and inversely proportional to its density. This relationship is known as Newton’s law of viscosity and is used to model and analyze fluid behavior.

In addition to influencing the flow of liquids, gases and other matter in our environment, fluid dynamics has significant impacts on a wide variety of other applications. From calculating forces and movements on airplanes to determining the mass flow rate of oil in pipelines, understanding the principles of fluid dynamics can help engineers design and build systems that benefit human society.

The science behind fluid dynamics is often complicated, but the concepts are fairly straightforward and can be easily explained to non-experts. A rough division is made between ideal and non-ideal flows, and this relates to the viscous effects that occur in regions of a flow close to a solid surface. In a region far from a solid surface, these effects are not present and the flow can be mathematically treated as inviscid.

Understanding how fluids behave can be facilitated through the use of visual representations, such as streamlines and pathlines. A streamline is a line that represents the tangent to a velocity vector at any point in a fluid. A pathline, on the other hand, shows all of the paths that individual elements of the fluid have taken through a given area over time. A streamline and a pathline are usually drawn together to form a contour map of the fluid’s velocity.

A common technique to evaluate a fluid’s viscosity is to test its resistance to the dropping of a ball into it. The longer the ball takes to drop, the higher the fluid’s viscosity rating will be. In the world of physics and engineering, we commonly refer to dynamic viscosity in terms of centipoise. One centipoise is defined as the viscosity of a fluid in relation to the dynamic viscosity of water at 20 degrees Celsius.

As an example, peanut butter has a 250,000 centipoise rating, meaning that it would take a long time for someone to fill a jar with it using a spoon. The best way to reduce a liquid’s viscosity is to heat it before adding it to another container, and this is why we pour syrup or honey into a glass of hot coffee. This process will cause the fluid to become thinner, and therefore less resistant to shear, so it will flow more easily into its container.