When the word “fluid” is mentioned in everyday language, many think that it simply refers to liquids. However, in the world of physics, the term fluid has an entirely different meaning. It denotes any liquid or gas that has the ability to adjust or conform to the shape of the container in which is it being held. Fluid mechanics refers to the study of fluids in motion and at rest. Fluid mechanics is usually divided into two subsections. The first subsection is referred to as fluid statics. This is primarily concerned with studying those fluids are stationary or static. The second sub-section is fluid dynamics. This is the study of fluids that are moving or flowing. Fluid dynamics is the wider of the two sections and is further subdivided into aerodynamics and hydrodynamics which are studies of air flow and water flow respectively. Fluid dynamics finds a lot of application in everyday life. This is both at the domestic and the industrial level.
One of the elements of fluid mechanics that has several applications is the Bernoulli’s principle. The Bernoulli’s principle can be seen, for example, in river flow. One will notice, for example, that a river exhibits different speeds in its course. When a river is flowing in a wide and unconstricted region, it will tend to flow slowly. When the river is flowing in narrower region that, for example, is constricted by rock walls or canyons, its speed rises almost dramatically. This can be explained through the Bernoulli’s principle that is one of the components of fluid mechanics. When a fluid moves through a section with a wider cross-sectional area to a narrower one, the volume of this fluid that moves through a given length in a given period must not change (Daugherty & Franzini, 1965). This, therefore, means that for the same volume to move through a given length when the width of that section has gotten smaller, the fluid must move at a higher speed or with a greater dynamic pressure.
This principle is also applied in airplanes, particularly in the wings (Daugherty & Franzini, 1965). The design of the airplane’s wing can be considered to be an airfoil. An airfoil essentially adopts the shape of an asymmetrical airdrop that is laid on its side (Science Clarified, n.d). The thicker end of this “teardrop” is towards the direction of the airflow. Air that is moving fast hits the airfoil’s front and this airstream is forced to divide with part of it flowing under the wing and the other flowing over the wing. The airfoil’s upper surface is about curved while the lower surface is relatively straighter (Science Clarified, n.d). Consequently, the airstream above the wing or on top of the wing has a larger distance to cover or flow than the air flowing below the wing. According to fluid mechanics, all fluids tend compensate for the various objects that are on their way or that they have contact with (Science Clarified, n.d). Therefore, the airstream at that top of the airfoil will tend to flow at a faster speed than that flowing below or under the wing when the two streams reach the airfoil’s rear end. According to the Bernoulli’s principle, greater speed of fluids is an indication of lower pressure, and this means that the higher pressure on the bottom keeps the plane aloft. This is an exemplary example of fluid mechanics at work (Science Clarified, n.d).
Another real life example of fluid mechanics is creating a draft in a room in order to cool it down. For example, one may be in a room that is very hot and stuffy. However, the room may have a window that opens to the outside where the air is presumably cool. Here, one may be prompted to open the window in order to let the cool air in. The room may become cool for a few minutes abut after some time one may notice that the temperatures are still the same, and the room remains stuffy. After opening the front door, however, a cooling effect is achieved, and the room essentially stops being stuffy and is cool.
This another perfect application of fluid mechanics at work. Normally, when the front door is closed, the area inside the room has a relatively higher pressure when compared to the air pressure that is directly outside of the window. (Science Clarified, n.d) Air is a fluid, and when the window is opened, it will enter into the room. However, the pressure inside the room will reach an optimum point which will prevent any more air from making its way into the room. This is in accordance with the rules of fluid mechanics that states that air tends to flow from regions of high pressure to regions of low pressure and never vice versa. However, once the door is opened, the air inside the room which is at a higher pressure will flow outside the room through the door and into the hallway that is characterized by low pressure (Science Clarified, n.d). Consequently, the high pressure that is inside the room decreases significantly, and this means that the air outside the window can enter, and the cooling effect is achieved.
A pump is another device that exemplifies the real life use of fluid dynamics. This is a device that is essentially made to move fluids. The device utilizes the pressure difference phenomenon that has been explained earlier in this discussion. A fluid moves from a region of higher pressure to a region of lower pressure (Biringen & Chow, 2001). One example of a pump is the siphon hose that is utilized in the drawing of gas from the fuel tank of a car. When sucking takes place at one of the hose’s ends, and area of low pressure is created. This is in comparison with the gas tank that has a relatively high pressure (Science Clarified, n.d). This causes gasoline to move from the tank to the hose’s end that has low pressure.
A piston pump is also another application of fluid mechanics although it works in a different manner (Science Clarified, n.d). This pump comprises of a cylinder that is vertically oriented and along which the piston falls and rises. There are two valves close to the cylinder’s bottom. One of the valves is the inlet valve. It is through this valve that fluid flow into the cylinder takes place. The other valve is the outlet valve through which fluid flow out of the cylinder takes place. During the down stroke, closure of an inlet valve occurs while the other valve opens. The piston provides pressure that then forces the fluid through the now open outlet valve. The piston valve has many applications with one of them being an automobile’s engine that involves the pumping of gasoline (Science Clarified, n.d).
Another example of fluid mechanics being applied is in hot air balloons. A hot air balloon goes up because the air contained inside the balloon is usually hotter than that which is contained outside the balloon (Biringen & Chow, 2001). This difference in density, as well as pressure, is what allows the balloon to essentially float. There are also several forces that act on the balloon with buoyancy being one of them. This force that arises from concepts of fluid tends to push upwards on this balloon. On the other hand, the balloon’s weight as well as the drag force together with that is contained inside acts in a downward direction. In addition, the pressure and temperature of the balloon vary with the height of movement or elevation (Biringen & Chow, 2001). This, therefore, means that the density inside and outside the balloon also varies with elevation. The density changes affect the buoyant’s and drag forces’ magnitude, and this also has an effect on the velocity that the balloon acquires while rising (Biringen & Chow, 2001).
The application of fluid mechanics can also be found in hydraulic presses, for example, the hydraulic jack that is often used in cars when one wants, for example, to change the tires (Mott, 2006). This can be used to raise a car that is currently stationed on the auto-mechanic shop’s floor. The section beneath the shop has a chamber that contains a given quantity of a fluid. The chamber has two ends and on each one, there are cylinders that stand side by side. Each of these cylinders has a piston. Flow occurs between the two cylinders through a connecting channel and valves are used to control this flow. This system works according to Pascal’s principle. This means that when force is applied through the pressing of the piston in one of the cylinders, uniform pressure is yielded and this stimulates an output in the other cylinder. The piston is pushed up, and this leads to the car being raised.
The dominant application of fluid mechanics seems to be the one that utilizes pressure difference. As described pressure difference stimulates the movement of fluids from one point to the other and usually, fluid flow usual takes place from a region of high pressure to one of low pressure (Schwab, 1998). There are many processes related to this that occur naturally in the environment but sometimes, the pressure difference has to be induced if one wants a fluid to flow from one direction to the other, for example the drafting example that was explained earlier where cool air is stimulated to flow into the room through the creation of an artificial pressure difference (Schwab, 1998).
As shown, the term fluid does not simply refers to liquids as is commonly expressed in the common language. Alternatively, in the world of physics, the term fluid has an entirely different meaning and basically denotes any liquid or gas has that has the ability to conform or adjust to the shape of the container in which is it being held. It is from this definition that the concept of fluid mechanics emerges and as has been shown, it refers study of fluids in motion and at rest. Fluid mechanics is a concept that is widely applicable in everyday life. This discussion has shown how it can be applied both at domestic levels, such as stimulating the entrance of cold air into a room and also at an industrial level or a large scale level.
Biringen, S., & Chow, C. Y. (2011). An introduction to computational fluid mechanics by example. John Wiley & Sons.
Daugherty, R. L., & Franzini, J. B. (1965). Fluid mechanics with engineering applications.
Schwab, C. (1998). p-and hp-finite element methods: Theory and applications in solid and fluid mechanics. Oxford: Clarendon Press.
Mott, R. L., Noor, F. M., & Aziz, A. A. (2006). Applied fluid mechanics (Vol. 4). Prentice Hall.
Science Clarified. (n.d.). Fluid Mechanics- Real-life applications. Retrieved December 8, 2014, from http://www.scienceclarified.com/everyday/Real-Life-Chemistry-Vol-3-Physics-Vol-1/Fluid-Mechanics-Real-life-applications.html