Mechanism of swirl generation in sink flow.

This paper aims to study the possibility of swirl generation in the sink flow in the absence of external factors, i.e., self-rotation. It is motivated by the fact that there is no consensus among the researchers about either the possibility or impossibility of this phenomenon. The axisymmetric model of the problem is simulated using a stream function-vorticity-circulation formulation. The results showed that there is not sudden change in the value of azimuthal velocity and circulation. Therefore the flow is stable for all the Re numbers tested (i.e., 0.265 < Re < 5.3). In addition, it is concluded that, in general, the self-rotation phenomenon would not occur for two reasons: first, the net value of circulation in the flow domain would not increase relative to its inlet value; second, the current numerical simulations, which also agree with the previous experimental results, show that appearance and non-appearance of swirl is related to viscous force. [ABSTRACT FROM AUTHOR]