caelum -- NX Thermal Analysis Reference Manual

http://www.cadfamily.com/a/CAE_FEA_CFD/caelum/caelum----NX-Thermal-Analysis-Reference-Manual_6540.html

where:

T2 is a convergence parameter specified on Card 9 PARAM ILU. T2 defaults to 1.E-8.

To accelerate convergence, an approximate inverse matrix is used as a preconditioner. The

preconditioning matrix is created using the Incomplete Lower-Upper factorization method. LFIL

is the maximum number of terms in each row of the preconditioning matrix, and its initial value

defaults to 10. LFIL may be redefined on a Card 9 PARAM ILU Card.

The preconditioning matrix is created once every 10 iterations for steady-state runs, and once

every 10 integration time steps for transient runs. In addition, before every solution the diagonal

terms of the GG matrix are checked to see if they have changed since the last time the

preconditioning matrix was updated. If they have changed by more than 100%, the

preconditioning matrix is automatically updated.