Instabilities of a Spatial System of Articulated Pipes Conveying Fluid

A spatial system of two articulated pipes conveying fluid is examined analytically and experimentally. As the flowrate is increased, stable equilibrium may be lost by either divergence (static buckling) or by flutter (oscillations with increasing amplitude), depending upon the value of an angle β which measures the “out-of-planeness” of the system. It is found that in the range O < β < 90 deg there exists a transition value β* below which stability is lost by flutter and above which stability is lost by divergence.