//Variable declaration:
//From example 6.12, we have:
D = 2.0/12.0                    //Diameter of pipe in feet (ft)
Re = 1440.0                     //Reynolds number

//Calculation:
Lc = 0.05*D*Re                  //Length of pipe (ft)

//Result:
printf("The pipe length to ensure a fully developed flow is: %f ft.",Lc)
printf("This is an abnormally long calming length for a pipe (or tube) in a heat exchanger.")