Here, the shaded cylinder of fluid flows past point P in a uniform pipe in time t. This can occur when the speed of the fluid reaches a certain critical speed.įigure 14.26 Flow rate is the volume of fluid flowing past a point through the area A per unit time. In turbulent flow, the paths of the fluid flow are irregular as different parts of the fluid mix together or form small circular regions that resemble whirlpools. The second diagram represents turbulent flow, in which streamlines are irregular and change over time. This is a special case of laminar flow, where the friction between the pipe and the fluid is high, known as no slip boundary conditions. Note that in the example shown in part (a), the velocity of the fluid is greatest in the center and decreases near the walls of the pipe due to the viscosity of the fluid and friction between the pipe walls and the fluid. Newton described the relationship between forces and motion using three basic principles, still used today.
Dynamics, or the study of forces, was very simply and effectively described by Sir Isaac Newton in 1686 in his masterpiece Principia Mathematica Philosophiae Naturalis. The first fluid exhibits a laminar flow (sometimes described as a steady flow), represented by smooth, parallel streamlines. To answer that question, we must study forces and their application. The diagrams in Figure use streamlines to illustrate two examples of fluids moving through a pipe. The velocity is always tangential to the streamline. A streamline represents the path of a small volume of fluid as it flows. The colors represent the relative vorticity, a measure of turning or spinning of the air.Īnother method for representing fluid motion is a streamline. Notice the circulation of the wind around the eye of the hurricane. Figure 14.24 The velocity vectors show the flow of wind in Hurricane Arthur.
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