Sharif University of Technology Scientia Iranica 1026-3098 24 4 2017 08 01 Unsteady impulsive oblique stagnation-point flow impinging axisymmetrically on a vertical circular cylinder with mixed convection heat transfer 1966 1974 4287 10.24200/sci.2017.4287 EN R. Bayat Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, P.O. Box 91775-1111, Iran A. B. Rahimi Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, P.O. Box 91775-1111, Iran Journal Article 2015 07 21 For 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