Lattice Boltzmann simulations of flow inside a converging and diverging nozzle with the insertion of single and multiple circular cylinders

The present study delivers several numerical experiments, conducted on a converging–diverging horizontal nozzle with the insertion of single and multiple circular cylinders. The fluid enters from the inlet wall, strikes the nozzle's and cylinder's walls multiple times, affecting the entire flow region, and, finally, leaves the nozzle through the outlet wall. This entire process leads to many new unseen things. The lattice Boltzmann method with a multiple relaxation time scheme is adopted for all the numerical experiments. The physical parameters that are investigated in the present study are Reinlet, Recylinder, drag and lift coefficients, Mach number (Ma), and pressure difference(Δp). It is found that the position of the circular cylinder affects the transition zone between a steady state and an unsteady state. For every different position, a different transition zone is observed. In the case of the presence of multiple cylinders, the effect of the position of every cylinder counts for the net transition zone. Moreover, the variation in the drag and lift coefficients and pressure difference are represented throughout the study.