An analysis of a two cylinder-fluid interaction at critical gap spacing by a cell boundary element method

Incompressible viscous, uniform flow past two parallel cylinders of equal diameter at a critical gap spacing g*=0.90 to 1.10 is investigated using the viscous cell boundary element method. In this critical flow zone an irregular interchange of in-phase and anti-phase wake flows is observed and the switching mechanism between the states is investigated. Numerical studies undertaken at space increments of 0.05, including the central case g*=1.0, detail the flow characteristics in time and space domains. Probability and power spectral analyses are presented to illustrate the statistical characteristics of the drag and lift flow parameters and vortex shedding patterns assessed through examination of their frequencies