This paper examines the unsteady two-dimensional boundary layer heat and mass transfer features of viscoelastic fluid flow near the neighborhood of forward and rare stagnation points. The heated circular cylinder is immersed in a viscoelastic fluid and the forward and rare stagnation points occurs near downward and upward directions of the cylinder respectively. The velocity near the surface of the cylinder is assumed to be zero and at very large distance from cylinder a uniform free stream velocity is spontaneously started in vertical direction. A non-similar transformation reduces the set of partial differential equations into non-similar partial differential equations. The transformed non-linear partial differential system is solved by using Keller box method. This technique shows well-behaved solutions for the steady-state (large time) and transient (small time) flows near the boundary layer region. Moreover, the body force present in this phenomena is in the form of convection which gives assisting (greater than zero) and opposing flows (less than zero). Parameters like the viscoelastic parameter, the convection parameter and the stagnation point parameter (forward and rare stagnation points) are found to control the flow field. Moreover, the Schmidt and the Prandtl numbers are used to control the concentration and temperature distributions. Features of several parameters on the non-dimensional concentration, temperature, local Nusselt and Sherwood numbers are viewed through graphs (2-d and 3-d) and tables. Contour images are plotted in order to visualize the three dimensional surface into two dimensional plane.

本文研究了粘滞性流体流动的非定常二维边界层传热和传质特征，这些粘弹性流体在正向和稀疏停滞点附近。将加热的圆柱体浸入粘弹性流体中，并且向前和稀有的停滞点分别出现在圆柱体的向下和向上方向附近。假定圆柱表面附近的速度为零，并且在距圆柱非常大的距离处，在垂直方向上自发地启动了均匀的自由流速度。非相似变换将偏微分方程组简化为非相似偏微分方程。变换后的非线性偏微分系统采用凯勒盒法求解。该技术为边界层区域附近的稳态（大时间）和瞬态（小时间）流提供了行为良好的解决方案。此外，在这种现象中出现的体力是对流的形式，它可以提供辅助作用（大于零）和相反的流动（小于零）。找到诸如粘弹性参数，对流参数和停滞点参数（正向和稀有停滞点）之类的参数来控制流场。而且，施密特数和普朗特数用于控制浓度和温度分布。可通过图形（2-d和3-d）和表格查看无量纲浓度，温度，局部Nusselt和Sherwood数的几个参数的特征。