Published online by Cambridge University Press: 09 September 2015
We analyse the low-Reynolds-number flow generated by a cylinder (of radius $a$ ) in a stream (of velocity
$U_{\infty }$ ) which has a uniform through-surface blowing component (of velocity
$U_{b}$ ). The flow is characterized in terms of the Reynolds number
$Re$ (
$=2aU_{\infty }/{\it\nu}$ , where
${\it\nu}$ is the kinematic viscosity of the fluid) and the dimensionless blow velocity
${\it\Lambda}$ (
$=U_{b}/U_{\infty }$ ). We seek the leading-order symmetric solution of the vorticity field which satisfies the near- and far-field boundary conditions. The drag coefficient is then determined from the vorticity field. For the no-blow case Lamb’s (Phil. Mag., vol. 21, 1911, pp. 112–121) expression is retrieved for
$Re\rightarrow 0$ . For the strong-sucking case, the asymptotic limit,
$C_{D}\approx -2{\rm\pi}{\it\Lambda}$ , is confirmed. The blowing solution is valid for
${\it\Lambda}<4/Re$ , after which the flow is unsymmetrical about
${\it\theta}={\rm\pi}/2$ . The analytical results are compared with full numerical solutions for the drag coefficient
$C_{D}$ and the fraction of drag due to viscous stresses. The predictions show good agreement for
$Re=0.1$ and
${\it\Lambda}=-5,0,5$ .