Sharif University of TechnologyScientia Iranica1026-309824420170801Unsteady impulsive oblique stagnation-point flow impinging axisymmetrically on a vertical circular cylinder with mixed convection heat transfer19661974428710.24200/sci.2017.4287ENR. BayatFaculty of Engineering, Ferdowsi University of Mashhad, Mashhad, P.O. Box 91775-1111, IranA. B. RahimiFaculty of Engineering, Ferdowsi University of Mashhad, Mashhad, P.O. Box 91775-1111, IranJournal Article20150721For the rst time, the problem of impulsive oblique stagnation-point flow on a vertical cylinder along with mixed convection heat transfer due to buoyancy forces has been solved in this study. The <br />uid at rest with uniform temperature, T1, around the cylinder starts flowing towards it at strength rate of k, and the cylinder temperature rises to Tw at t = 0, simultaneously. The governing equations induced by the impinging flow on the constant-temperature vertical cylinder at any obliqueness angle, , have been reduced<br />to ODEs by using similarity transformations, and then they have been solved numerically. Considering a sample case of incompressible flow with Re = 1 and Pr = 0:7, the results of Nusselt number and similarity functions of velocity and temperature distributions have been obtained for dierent values of time and angle, . At the initial instants of time, the Nusselt number, regardless of 's magnitude, has large values; for example Nu = 5:1 at = 0:01. As time passes, the value of the Nusselt number reduces intensely within a<br />short period of time (until 0:4), and then it changes with a moderate reduction rate, such that in the steady-state situation, its value reaches 0.67, 0.61, and 0.51 for obliqueness angles = 10, 30, 60.https://scientiairanica.sharif.edu/article_4287_223aebe933b109b00128c02b579f1fc9.pdf