AEATECHNOLoGY ENGINEERING SOFTWAR CFX4 Basic Concepts All terms are discretized in time and space linear equations are obtained -∑ALm P=1,2,…, NCELL Discretization Transient term backward difference crank-Nicolson Convection term Hybrid, HUW, QUICK, CCCT, etc Diffusion term: 2nd order central differencing The linear equation is spatially coupled Direct matrix inversion is too expensive, so iterative linear equation solvers are used >ICCG. AMG. Stone. line relaxation etc CFX-4 CFX4.3V4.3.1H Introductory Training(Dec 1999)CFX-4 Introductory Training (Dec 1999) 8 -3 CFX-4.3 V4.3.1H CFX-4 Basic Concepts All terms are discretized in time and space, linear equations are obtained - Discretization > Transient term: backward difference, Crank-Nicolson > Convection term: Hybrid, HUW, QUICK, CCCT, etc. > Diffusion term: 2nd order central differencing. - The linear equation is spatially coupled. Direct matrix inversion is too expensive, so iterative linear equation solvers are used > ICCG, AMG, Stone, line relaxation, etc. Ap p Anb S nb  - nb = u p = 1, 2,  , NCELL