LIMPO: An improved version of the PISO algorithm for turbulent swirling flows

Describes the solution of implicitly discretized fluid flow equations, for turbulent swirling flows, by means of a new iterative method, based on the PISO algorithm. The technique is based on the splitting of the solution process into a series of steps, where, at each step, pressure operations are dissociated from those on velocities. The split sets of equations are solveable by standard numerical techniques. However, in this work, the influence of turbulent quantities and tangential velocity on the momentum equations is taken into account in the splitting process, through the source terms of the discretized equations. Does this by embedding a predictor and a corrector step for the turbulent quantities and for the tangential velocity into the PISO algorithm. This improvement to the standard PISO algorithm leads to a considerable reduction of the computational effort in achieving the same numerically converged solution. Applies the algorithm, in conjunction with a finite-volume technique, to simulate two different geometries for two-dimensional (axisymmetric) isothermal turbulent steady-flows, with and without swirl. Compares the results with predictions of the same flows obtained other iterative methods (SIMPLE) and (PISO). Shows that the algorithm presented herein always exhibits a better efficiency in getting exactly the same final predictions, as far as the number of iterations for convergence and the required central processing unit time are concerned.