An exhaust device using no power but using natural wind is proposed. The structure is very simple, and is constructed by a circular cylindrical vessel and a slit producing a jet. The swirling jet produces a low pressure region and inhale the gas. The three-dimensional flow structure is clarified by the numerical calculations using the finite-difference lattice Boltzmann method. Effect of swirling jet and the spiral structure of the flow is clarified by comparing two other cases.

We conducted dynamic mode decomposition control (DMDc) to suppress the unsteady flow for a cylinder located in uniform flow and verified the results via computational fluid dynamics. The separation point was controlled by the blowing and suction generated from the cylinder surface, resulting in reduced lift oscillation. The unsteady flow around the cylinder located in uniform flow can be qualitatively estimated and controlled using DMDc.