10-08-2017, 12:47 PM
The PISO (Implicit Pressure with Operator Division) algorithm was proposed by Issa in 1986 without iterations and with large steps of time and a less computational effort. It is an extension of the SIMPLE algorithm used in Computational Fluid Dynamics (CFD) to solve the Navier-Stokes equations. PISO is a pressure-velocity calculation procedure for the Navier-Stokes equations originally developed for the non-iterative calculation of the unstable compressible flow, but has successfully adapted to steady-state problems. FLOOR involves a predictor step and two-step corrector and is designed to satisfy mass conservation by predictor-corrector steps.
The algorithm can be summarized as follows:
1. Set the boundary conditions.
2. Solve the discretised momentum equation to calculate an intermediate velocity field.
3. Calculate the mass flows on the faces of the cells.
4. Solve the pressure equation.
5. Correct the mass flows on the faces of the cell.
6. Correct the speeds on the basis of the new pressure field.
7. Update the boundary conditions.
8. Repeat 3 for the prescribed number of times.
9. Increase the time step and repeat from 1.
The algorithm can be summarized as follows:
1. Set the boundary conditions.
2. Solve the discretised momentum equation to calculate an intermediate velocity field.
3. Calculate the mass flows on the faces of the cells.
4. Solve the pressure equation.
5. Correct the mass flows on the faces of the cell.
6. Correct the speeds on the basis of the new pressure field.
7. Update the boundary conditions.
8. Repeat 3 for the prescribed number of times.
9. Increase the time step and repeat from 1.