The nodeForAutoThreading numbering scheme is described below.

The basic types of nodes classified automatically

0 - Solid
1 - Fluid
3 - Boundary (automatically categorized on subtypes)

Periodic boundary nodeForAutoThreading types

The condition most often used on inlets and outlets to/from the system and periodic walls.

4 - Periodic boundary nodes

Dirichlet velocity boundary nodes

The condition most often used on inlets to the system (inlet velocity).

20 - Basic type (automatically categorized on subtypes)
21 - North velocity
22 - South velocity
23 - East velocity
24 - West velocity
25 - Bottom velocity
26 - Top velocity

Neumann pressure boundary nodes

The condition most often used at outlets from the system (pressure outflow).

30 - Basic type (automatically categorized on subtypes)
31 - North pressure
32 - South pressure
33 - East pressure
34 - West pressure
35 - Bottom pressure
36 - Top pressure

Dirichlet velocity 0 boundary nodes

The condition most often used on the walls of the system (wall velocity 0).

40 - Basic type (automatically categorized on subtypes)
41 - North vel. 0
42 - South vel. 0
43 - East vel. 0
44 - West vel. 0
45 - Bottom vel. 0
46 - Top vel. 0

Bounce-back boundary nodes

The condition most often used on the walls of the system.

61 - Bounce-back 2