Power Scaling of Radial Outflow: Bernoulli Pads in Equilibrium

Abstract

A Bernoulli pad uses an axial jet to produce radial outflow between the pad and a proximally located parallel surface. The flow field produces a force between the surfaces, which depends upon their spacing h. The direction of this force is repulsive as h approaches zero and becomes attractive as h increases. This yields a stable equilibrium point heq, where the force is equal to zero. The present computational work indicates that a power-law relationship exists between heq and the inlet fluid power required to sustain this equilibrium spacing when each is appropriately scaled. This scaling is derived principally from the wall shear; an additional term incorporating the inlet Reynolds number is used to account for the force applied to the system. The relationship is valid over a range of forces acting on the system, geometric, and material properties.