$6\mathrm{.}9\mathrm{.}18$ We will see in Chapter $8$ that the pressure drop in fully devel$-$ oped pipe flow is sometimes computed with the aid of a friction factor, defined by e concepts of modeling and simitide $1$o deve $.$npiodidailn@ioolatrairl Ap P aidli oj noiuloe JOSK$3$ DS $20$V L wj$9$d qidanoislar arl ai Jsrw odu$]$ sdl Jnsiber where V is the average velocity, D is the pipe diameter, and is the length of pipe over which Ap occurs. For laminar fully developed flow, fcan be evaluated from ebal e $1$alto sn sbnll ya shinsanos avibe s asdl bns boxll ei yobrulyo vonni ad$"$ o vipolov uslugns ne coituloeae as$,$adaido plal f$=$ Re Co eolo$12-1$siva arl silsM there where C is a constant and Re is the Reynolds number, given by Re $=$ pVD$/$p$.$ Find the constant C for flow in a circular tube.