Physical Laws Governing Fluid Flow Resistance, and Pressure - Assignment Example

Consider the case in which fluid passes through a pipe. The pressure of the fluid varies as per the size of the pipe hole. When the pipe hole narrows the fluid flows more quickly. Bernoulli's Principle tells us that the pressure decreases as the fluid flows more quickly through the narrow sections. V2/2 + P/p +gz = constant where v is the velocity at a point, P pressure p density, g acceleration due to gravity, and z is the height above the reference level. This equation relates the pressure, velocity, and height in the steady motion of an ideal fluid.

Resistance

The resistance to the flow of a fluid is associated with the viscosity of the fluid. The frictional force exerted by fluids is called viscous force. The property of fluid by which it opposes the relative motion between adjacent layers is called viscosity. It is the internal friction of the fluid. In other words, the force required to move a plate at constant speed against the resistance of a fluid is proportional to the area of the plate and the velocity gradient perpendicular to the plate. The constant of proportionality is called the viscosity. In fluids, viscous force is acting tangential to the fluid layer opposing the flow. Therefore it is necessary to apply external force to maintain the relative motion between fluid layers; otherwise, the motion of the fluids will be stopped due to internal friction.

            The principle of continuity states that, if an ideal fluid flows through a tube in streamlined motion then the product of the cross-sectional area of the tube and the velocity of flow is the same at every point in the tube. If A is the cross-sectional area and v is the velocity of the flow of liquid then as per the principle of continuity Av = constant.