THREE EXACT SOLUTIONS OF INCOMPRESSIBLE POTENTIAL FLOW INDUCED BY TWO CIRCLES

Lagally (1929) has given the exact solution for the two dimensional incompressible potential flow indued by two fixed circles in a uniform stream. In this paper, three exact solutions are obtained for two dimensional incompressible potential flow induced by two circles moving or expanding in a still fluid in three cases: (i) expansion (or contraction) of themselves, (ii) approach to (or departure from) each other, (iii) their movements perpendicular to the connected-centre-line in opposite directions.