Factors Affecting Fluid Friction

The amount of Frictional force by a fluid on an object depends upon the following:

Nature of fluid

The thinner the fluid, the lesser the fluid friction will be, and vice versa. The different types of fluid offer different extents of resistance or the viscous drag of the object flowing through it. For example, an object moving in honey experiences a much larger viscous force than moving in plain water as the density of honey is much larger than the density of water and hence it offers greater resistance to the flow of the object.

The viscosity of fluid

The viscosity of fluid plays a major role in determining the velocity of the object which flows through it. The more viscous the fluid the denser it is and hence the movement of any material inside it is restricted or experiences resistance to its motion. The denser the liquid the more viscous drag it creates.

The shape of the body

Other figures feel more drag than the body with a streamlined shape which begins and ends in points like the shape of a fish. The shapes of vehicles are designed to reduce the surface of contact during motion. It plays a major role in the smoother flow be it in liquid or in gases. The shape of the body has to be in accordance with the medium in which it is flowing or moving or else it experiences a major resistance to its movement which makes the task very time-consuming. Hence, to reduce this most of the bodies have a streamlined shape. This ensures that at the start and at the end the surface of contact is minimum and hence the fluid friction.

The temperature

The fluid friction of all gases increases with an increase in temperature since the fluid friction of a gas is directly proportional to the square root of the absolute temperature. (This result is obtained from the kinetic theory of gases).

The fluid friction of liquids and other substances also increases proportionally with the increase in temperature.

The surface area of the body

The more the surface of the body more is the fluid friction. For example A horizontal moving body can cut through the liquid more easily than a body moving vertically. For a body with a large surface area, the fluid friction increases accordingly and hence its movement or flow becomes difficult.

Speed of the body

Friction and speed are directly proportional to each other. On increasing the speed the fluid friction or drag also increases proportionally. For example: An airplane flying at the highest speed of 1000km/hr. Will face a greater frictional force or drag of air than another similar airplane which is flying at a speed of 600km/hr. Or a high-speed boat experiences lesser fluid friction than a slow-moving fish.

The pressure on the body

The fluid friction increases proportionally with the increase in the pressure on the body. With the increase in pressure, it becomes difficult for the molecules to travel from one place to another place and also over the layers. Hence, there is a huge amount of resistance to the flow of the fluids.

Fluid friction occurs between fluid layers that are moving relative to each other. This internal resistance to flow is called viscosity or viscous drag or fluid friction. In normal terms, the viscosity of a fluid is described as its “thickness” of the fluid. Thus, water is “thin”, having a lower viscosity, while honey is “thick”, having a higher viscosity. The less viscous the fluid, the greater its ease of deformation or movement.

All real fluids (except superfluids) offer some resistance to shearing and therefore are viscous. Although the term “fluid” includes both the liquid and gas phases, in common usage, “fluid” is often used synonymously with “liquid”. Liquids and gases are called fluids because they can be made to flow or move. In any fluid, the molecules themselves are in constant, random motion, colliding with each other and with the walls of any container. In this article, we will learn in detail about fluid friction, its properties, example and more.