Flow induced vibrations, drag force, and pressure drop in conduits covered with biofilm

Abstract

Biofilm was grown in closed conduit reactors under turbulent flow conditions. Structural development of the biofilm suggests that individual microcolonies behave like blunt bodies shedding vortices. The microcolonies assumed elongated forms, termed ""streamers"", possibly because of an exerted pressure drag force. The streamers when entrained in the water flow vibrated rapidly dissipating kinetic energy from the bulk liquid. The energy was transferred through the biofilm causing the underlying microcolonies to oscillate. The measured pressure drop was partially attributed to the loss of energy due to these flow induced vibrations and oscillations.