Dissipation time

Examples how dissipation is governing the flow can be found abundantly in nature. Since the dissipation characteristic time isn't commonly studied in a ``regular'' fluid mechanics we first introduce two classical examples of dissipation problems. One problem is dealing with the oscillating manometer and two, ``rigid body'' brought to a rest in a thin cylinder.

Figure: The oscillating manometer for the example

= 0.5

Figure: Rigid body brought into rest.

perhaps the examples are not important? These examples illustrate that the characteristic time of dissipation can be assessed by thus given by . put Eckert's explanation Note the analogy between and , for which appears in both of them, the characteristic length, , appears as the typical die thickness.

put more expanded explanation for this equation

is it important to discuss the 2/3?