Section: CIVL 345 Fluid Mechanics Lab Experiment 1 - Properties of Fluids Student Name Date of Submission: Student ID Introduction: Properties of fluids play an important role in both fluid

statics and fluid dynamics. To distinguish one fluid from another, properties such as density, viscosity, and surface tension can be used. Aim: To determine density, specific gravity, and viscosity for different liquids. Theory: To determine the density of a liquid it is necessary to measure the mass of a known volume of liquid. Density p = The density of pure water at 20°C is 998.2 kg/m³ and this is often rounded up to 1000 kg/m³ for engineering purposes. Specific gravity is the ratio of the density of a fluid to the density of water. Pfluid Pwater S. G. = Viscosity is the measure of the fluidity of a fluid. For a Newtonian fluid, applied shear stress is proportional to the velocity gradient of the fluid and it is expressed as follows. mass volume du τιμ dy μ is called dynamic viscosity and it is a constant at a given temperature. In fluid mechanics, the term µ/p often appears and this is called the Kinematic Viscosity and is denoted by: V = 31Q μ Methods: Measuring density using Density Bottle and specific gravity using Hydrometer Task 1 Use this YouTube link to watch the experiment - watch until 5.37 minutes from the beginning. https://www.youtube.com/watch?v=StGbFkSevy0 Observations and calculations Calculate the properties of the liquids in the table. Liquid 1 Liquid 2 Liquid 3 Weight of Density Density Specific Density (g/ml) (kg/m³) volume Bottle (m³/kg) with liquid Weight of empty Density Bottle = The volume of Density Bottle = Density= = Weight of Density Bottle with liquid - Weight of empty Density Bottle Volume of Density Bottle Specific gravity Task 2 What is the specific gravity of the liquid measured by the hydrometer shown below? 0.990 1.000 10 20 -30 40 1.050 60 70 80 90 1.100 | ********** Measuring viscosity (kinematic viscosity) of a liquid using Stokes' law Many experimental methods can be used to determine viscosity and these are generally less direct than measuring the parameters in Equation. One common method is to consider the rate at which a smooth sphere will fall through a liquid for which it is required to determine the viscosity. Under equilibrium conditions, the shear or 'friction' forces on the sphere will equal its weight, and the sphere will fall at a constant velocity u, called the terminal velocity. Stokes' law is used to calculate the terminal velocity. U = gd² (o 18v (−1) Where d-diamerer of the sphere, g = gravitational acceleration, σ-density of the sphere, p= density of the liquid, v= kinematic viscosity of the liquid. Task 3 Use this YouTube link to watch the experiment on Terminal Velocity u. https://www.youtube.com/watch?v=AcsrBCEJZ-Y Use this YouTube link to watch the experiment on the viscosity effect. https://www.youtube.com/watch?v=69iUhlqFJFk Observations and calculations Density (kg/m³) Liquid 1 Liquid 2 Liquid 3 Liquid 4 Liquid 5 The diameter of the sphere- Density of the sphere = Calculate the terminal velocity and kinematic viscosity in the table. Time for the Terminal velocity, u (m/s) sphere to fall 200 mm in the liquid (s) Liquid 1 Liquid 2 Liquid 3 Liquid 4 Liquid 5 Terminal velocity, u = = travel distance time Kinematic viscosity, v (m²/s)