An approximate solution for the start-up flow of a power-law fluid in a tube

✍ Scribed by J. Sestak; M.E. Charles

• Publisher: Elsevier Science
• Year: 1968
• Tongue: English
• Weight: 686 KB
• Volume: 23
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(68)87097-6

✦ Synopsis

theoretical solution of the unsteady-state momentum equation for the start-up flow of a power-law fluid in circular tubes is presented. The solution is obtained with an approximate technique which has previously proved to be useful in solving other transport problems involving nonlinear partial differential equations and explicit asymptotic expressions for the velocity profiles and flow-rates as functions of time are given. The accuracy of the method is checked by comparing the results with the existing exact analytical solution of Gromekha-Szymanski which applies for the Newtonian case and the results are believed to be good approximations for moderate and large values of time. An interesting aspect of the results is the effect of the flow behaviour index and the imposed pressure gradient on the start-up time.