Bistability of turbulent flow in open-channel expansion: Characterization and suppression

Three-dimensional turbulent bistable flow (TBF) in an open-channel expansion is predicted using large eddy simulation. The free surface of TBF tracked the volume fluid method, coupled with level-set method. This paper aims to reveal ensemble-average characteristics and explore effective ways control bistability. For a given condition approaching expansion, either two stable states can possibly occur, depending on history. pressure field agrees well experimental data. velocity decomposed into deformation regions eddy-rotation Okubo–Weiss parameter. Turbulent eddies initiated by shear instability dominate those associated sidewall-friction force; this responsible for occurrence Fitting simple hump at flat-bottom way suppress presence shrinks cores breaks interaction between triggered instabilities induced friction forces; result increase uniformity turbulence, separation, vortex behavior.