PHONICS收敛.docVIP

Convergence Monitoring and Control Contents Convergence Monitoring Residuals RESREF Spot Value How to Assess Convergence Nett source Residuals Spot values How to use Graphical Monitor How to Achieve Convergence Linear Relaxation False Time Step Relaxation Advice on Relaxation Automatic Relaxation 5. Other relaxation control Solver Controls Limiting Values K-E Linearisation 6. Convert the residuals obtained with SELREF=T to residuals normalised by reference inflow quantities. Convergence Monitoring 1.1 Residuals The residuals are the quantities used in PHOENICS to monitor the convergence procedure. These are the imbalances in the FVE, defined as: ep = ap(? p) - ??(ai(? i-? p)) - S?? i=W,E,S,N,H,L,T where W,E,S,N,H and L denote space directions; T denotes time-direction. The aim of the computation is to reduce them to an acceptable magnitude. During the computation, the residuals are printed by Earth to the VDU, or are displayed graphically as shown in Figure 4. The frequency of display update is controlled by the PIL variable TSTSWP, which is set in the VR-editor Main menu / Output / Monitor update frequency panel. This panel also determines whether the data is shown graphically or in ASCII. Figure 1 shows the panel when the Main menu/output is clicked in VR-Editor. “Monitor display mode”: GRAPHICS and “Monitor update frequency”: 1 indicate that during the computation, the residuals are displayed graphically on the screen and updated every iteration. The monitor-cell location for the spot values are also set here. Please note that the monitor update frequency is internally calculated if LSWEEP is large and the user is not able to control the frequency. Figure 1. Main menu/Output panel in VR-Editor The PIL setting in a Q1 file should be: TSTSWP = N where n is the update frequency. N 0 indicates that the residuals are printed to the VDU in ASCII; N0 indicates that the re