pressure is derived from the definition that a perfect vacuum is the complete absence of any gas. This type of flow is known as a Couette flow. It is identical to the saturation pressure P sat of the liquid (P v =P sat). Mercury is the only fluid used in this application. measurement is commonly used to measure the pressure drop in a fluid system. Introduction to Pressure in Fluid Mechanics . It exerts force at all points on the sides and bottom of the container. The forces exerted by any static fluid are derived from the pressure distribution within the fluid. Pressure Measurements Pressure is an important variable in fluid mechanics and many instruments have been devised for its measurement. dependent on the velocity of flow. dependent upon the back pressure, i.e. Laminar shear of fluid between two plates. The force required for this action is a measure of the fluid's viscosity. (2.7) it can be seen that the pressure exerted by a fluid is dependent only on the vertical head of fluid and its specific weight; it is not affected by the weight of the fluid present. For example, atmospheric air decreases with altitude and that fluid pressure is the same in all directions. In this type of manometer there is Here is a list of the more common units of pressure measurement; all refer to the good old “American” PSI. Thus, in Fig. Many devices are based on hydrostatics such as barometers and manometers, i.e., determine pressure through measurement of a column (or columns) of a … 15 CV 33 FLUID MECHANICS NOTES MODULE-1 Fluids & Their Properties Fluid Pressure and Its Measurements by Dr. Nagaraj Sitaram, Principal & Professor, Amrutha Institute of Engineering & Management, Bidadi, Ramanagar District, Karnataka State Module -1: Fluids & Their Properties: Concept of fluid, Systems of units. Friction between the fluid and the moving boundaries causes the fluid to shear. Viscosity Viscosity is defined as the quantitative measure of tendency of a fluid to resist the forces of shear For the English system of units this could simply be psi and for the SI system it could be kPa. Solution The pressure in a pressurized water tank is measured by a multi-fluid manometer. • Vapor pressure (P v): The pressure exerted by its vapor in phase equilibrium with its liquid at a given temperature. Other pressure units of measure are the Atmosphere and the Bar, which are both roughly equivalent to atmospheric pressure at sea level on a “standard” day. • Partial pressure: The pressure of a gas or vapor in a mixture with other gases. The gage pressure of air in the tank is to be determined. Pressure is a normal stress, and hence has dimensions of force per unit area, or {ML-1 T-2}. Since a differential pressure is a measure of one pressure referenced to another, it is not necessary to specify a pressure reference. 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