The initial stage of bumps was electrodeposited at diffusion control overvoltage. Their shapes were observed by scanning electron microscopy and are discussed with numerical fluid dynamics computation. The bumps were electrodeposited either by varying the Peclet numbers or by varying dot diameters. For the Peclet number of 1.31 with 100 mu m dot diameter, the bump shows a maximum height hump at the circumference of upstream side and a lower hump exists at the downstream side. For 41.6, however, the hump at the upstream side slightly shifts to downstream and the hump becomes flat at the downstream side. The bump shows a maximum height at the upstream side for 200, 100, and 30 mu m in dot diameter for the Peclet number of 1.31. A lower hump exists at the downstream side. The bump shapes become flat for 15, 10, and 5 mu m dot diameters. These observed bump shapes are explained by the fluid dynamics calculations of vortex evolution and penetration flow. The calculated flux profiles coincide well with observed bump shapes.