The Segregated Step node (

) handles settings for one substep of a segregated iteration. This attribute uses a damped version of Newton’s method and can be used together with a
Segregated attribute node.
Use the Variables list to specify variables to be solved for in this step.
By default, all field or state components are included. Select Manual from the
Components list to specify which fields or states to include.
The variables are the ones that appear under the Dependent Variables node, and the components are the components listed by each of these (for instance,
u is the variable and
u,
v, and
w are the components for a Solid Mechanics model); see also the
Field and
State nodes.
Select a Linear solver for the linear systems associated with the quantities specified by
Variables. The available solvers are attribute nodes of the types
Direct and
Iterative.
Jacobian matrices requested by the linear solver during solution can be stored in a sparse or a
filled format, which you choose as
Sparse or
Filled, respectively, from the
Matrix format list. The default setting is
Automatic. In this case, the setting from the
Advanced node is used.
In addition, you can choose a matrix-free format, which you choose as Free. The matrix-free representation allows evaluation of matrix-vector products without assembling the matrix. This can reduce the memory usage significantly for solver algorithms that only use the matrix to multiply a vector, specifically:
See the Fully Coupled node’s
Method and Termination section for all settings except for the following, which has a slightly different behavior as described, and the residual smoothing (see below):
For a Stationary Solver or a parametric solver, if
Constant (Newton) is selected as the
Nonlinear method, choose a
Jacobian update:
Minimal (the default),
On every iteration, or
Once first iteration:
Select the Residual smoothing checkbox to enable that the residual smoothing term is applied to the residual on each iteration in the pseudo time-stepping solver.
The value in the Relaxation factor field (default: 0.1) controls the magnitude of the residual smoothing term.