*FLOW

Optional parameters

AMPLITUDE

Set this parameter equal to the name of the amplitude curve that gives the variation of reference pore pressure with time. If this parameter is omitted, the reference magnitude is applied immediately at the beginning of the step or linearly over the step depending on the value assigned to the AMPLITUDE parameter on the STEP option (see Defining an Analysis). The AMPLITUDE parameter is ignored for nonuniform seepage flow boundary conditions defined in user subroutine FLOW and for drainage-only seepage boundary conditions.

OP

Set OP=MOD (default) for existing FLOWs to remain, with this option modifying existing flows or defining additional flows.

Set OP=NEW if all existing FLOWs applied to the model should be removed. New flows can be defined.

Data lines to define uniform seepage

First line

Element number or element set label.
Seepage flow type label (see About the Element Library).
Reference pore pressure value, $u_{w}^{\infty}$ . (Units of FL⁻².)
Reference seepage coefficient value, $k_{s}$ . (Units of F⁻¹L³T⁻¹.)

Repeat this data line as often as necessary to define uniform seepage for various elements or element sets.

Data lines to define drainage-only seepage

First line

Element number or element set label.
Seepage flow type label (see About the Element Library).
Drainage-only seepage coefficient value, $k_{s}$ . (Units of F⁻¹L³T⁻¹.)

Repeat this data line as often as necessary to define drainage-only seepage for various elements or element sets.

Data lines to define nonuniform seepage

First line

Element number or element set label.
Seepage flow type label (see About the Element Library).
Optional reference pore pressure value. If given, this value is passed into user subroutine FLOW in the variable used to define the sink pore pressure.
Optional reference seepage coefficient. If given, this value is passed into user subroutine FLOW in the variable used to define the seepage coefficient.

The reference pore pressure value, $u_{w}^{\infty}$ , and reference seepage coefficient, $k_{s}$ , are defined in user subroutine FLOW for nonuniform flow.

Repeat this data line as often as necessary to define nonuniform seepage for various elements or element sets.