Peristaltic flow of Bingham fluids at large Reynolds numbers: A numerical study

•Yield stress can increase or decrease mean flow rate of peristaltic pumps depending on the flow Reynolds number.•Yield stress can increase or decrease mean flow rate of peristaltic pumps depending on the length and amplitude of the peristaltic wave.•Yield stress can increase or decrease particle trajectory depending on the Reynolds number.•For certain parameter values, a fluid's yield stress can suppress trap phenomenon. Peristaltic flow of a viscoplastic fluid which obeys the bi-viscous (Bingham) model as its constitutive equation is numerically studied in a planar two-dimensional channel using the multiple-relaxation-time lattice Boltzmann method (MRT-LBM). Numerical results could be obtained at large Reynolds numbers for arbitrary set of wavelength and amplitude ratios of the peristaltic wave. It is shown that depending on the Reynolds number, a fluid's yield stress may increase or decrease the time-mean flow rate of peristaltic pumps. Our numerical results also show that for yield-stress fluids there exists a threshold wave number above which the yield stress can accelerate fluid transport whereas below which it can have a decelerating effect. The yield stress is also predicted to diminish the size of the fluid bolus in the “trap” phenomenon for certain set of parameters.