The basic approach of the given measurement technique depends on the flowing medium (liquid/gas), nature of the flow (laminar/turbulent) and steady/unsteadiness of the medium. Accordingly, the fluid flow diagnostics are classified as measurement of local properties (velocity, pressure, temperature, density, viscosity, turbulent intensity etc.), integrated properties (mass and volume flow rate) and global properties (flow visualization). Also, these properties can be measured directly using certain devices or can be inferred from few basic measurements. For instance, if one wishes to measure the flow rate, then a direct measurement of volume/mass flow can be done during a fixed time interval. However, the secondary approach is to measure some other quantity such as pressure difference and/or fluid velocity at a point in the flow and then calculate the flow rate using suitable expressions. In addition, flow-visualization techniques are sometimes employed to obtain an image of the overall flow field. The parameters of interest for incompressible flow are the fluid viscosity, pressure/temperature, fluid velocity and its flow rate.