Computational Study of Free Jets Emanating from Circular and Lobed Orifice-Lattice Boltzmann Method

The Lattice Boltzmann method is an effective computational fluid dynamics tool to study complex flows. Unlike conventional numerical schemes based on discretization of macroscopic continuum equations, the Lattice Boltzmann method is based on particles and mesoscopic kinetic equations. Single-Relaxation Time Lattice Boltzmann Method (SRTLBM) with Smagorinsky LES model is applied to simulate high Reynolds number jet flows of single and multiphase flows emanating. The multi-block approach is implemented to refine the mesh when the high resolution is needed in the region around the core jet. An 2nd order accurate interface treatment between neighboring blocks is derived to satisfy the conservation of mass momentum and the continuity of the stresses across the interface. The bounce back boundary condition and curve boundary condition using extrapolation approach based on the idea of bounce back of the non-equilibrium part is implemented to impose the velocity boundary conditions at surfaces. The core jet length, velocity decay, turbulence intensity, vortex generation, jet breakup and noise spectrum analysis are studied for both circular and lobed jet orifices for a range of Reynolds number from 1000 to 72000. The pseudopotential Shan/Chen model Lattice Boltzmann Method is applied to study the small density ratio at low Reynold's number and low Weber number liquid jet breakup of the water/silicon oil multiphase fluid. Multiphase jet flow simulations at high Reynold's number and high Weber number are performed by utilizing OpenFOAM and predicted results are compared with results of documented experimental measurements.