S.3 Physics Fluid Flow Notes Caltec S.3

1 SUB -TOPIC: FLUID FLOW SPECIFIC OBJECTIVES The learner should be able to; • Carryout experiment to demonstrate streamline flow and turbulence. • State the relationship between pressure, velocity and closeness of streamlines. • Mention and explain practical applications of the relationship between pressure a nd velocity. • Identify and draw forces on an object falling in a fluid • Explain the factors that led to terminal velocity. • Explain the factors that lead to terminal veloc ity. • Displacement -time graphs to illustrate terminal velocity. Fluids in motion: A fluid is any substance that can flow freely. Fluids are usually either liquids or gases. Examples of fluids in motion include: • Sea water breaking against the seashore. • Flow of water in a river. • Columns of smoke swirling up from chimneys, e.t.c. Streamline and Turbulent Flow Streamline flow (steady flow) or laminar A streamline flow is one where, at a given point, each and every molecule of the fluid travels in the same direction and with same velocity. When a water tap is opened slightly, the water oozes out slowly in form of a thin smooth orderly stream. As the tap is opened further, eventually the water flows fast and the order disappears. Thus, by increasing the velocity, the flow changes from being steady and orderly to being unsteady and disorderly. The orderly flow of a fluid is termed as streamline flow. In streamline flow, the liquid molecules move in layers and do not cross from one layer to another i.e. each and every molecule of the fluid travels in the same direction and with the same speed . Streamline flow occurs when the fluid is moving at low speeds. NOTE: A streamline is a line indicating the path of the particles having a strea mline flow. Conditions …