This model represents the transition in a piping system from large diameter to small diameter. Similar to the pressure depth dependence model use imaginary surfaces to segregate volumes of fluid. Here we construct an imaginary surface in each section of pipe and consider the volume swept out by those surfaces as they are carried along by the fluid flow through the pipe.
Since the fluid is incompressible, the volume flow rate through both large and small pipes must be the same. The large pipe is twice the diameter of the small pipe so the large section has four times the cross section area of the small section. For the volume flow rates to be the same, the velocity through the small section must be four times the velocity through the large section.
Just click on the drawing area to enable the keyboard focus in that window and use the up and down arrow keys to step forward and backward through time as the fluid flows through the pipe. The displacements of the fluid in each section of pipe, its velocity and model time are reported in the upper left quadrant of the drawing area. The Clear button resets the initial conditions.
For details on the operation of applet controls, see the Model Controls help page.