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Chapter 6 Field and boundary initialisation
This chapter describes the initialisation of
fields and the configuration of the field’s boundary conditions.
Fields and boundary conditions are specified in field files,
e.g. p, U.
They are stored in time directories, with the initialised fields
almost invariably configured in the 0 directory, corresponding to the start
time 
.
The syntax of field files is introduced in a tutorial example in section 2.1.4 and then described more comprehensively in section 4.2.9 . They include: the dimensions entry for the dimensional units; internalField for the initial internal field values; boundaryField, where the boundary conditions are specified; and, optionally, sources to specify the conditions on fluid that is introduced by a mass or volume source.
This chapter begins with initialisation of the internalField using field functions in section 6.1 . The configuration of sources is then explained in section 6.2 . The rest of the chapter then discusses popular boundary conditions for setting the boundaryField section of field files.
6.1.1 The zonal field function
6.1.2 The surfaces field function
6.1.3 The coded field function
6.1.4 The distanceFunction field function
6.1.5 The fieldFunction field function
6.1.6 The timeFunction field function
6.1.7 Applied field functions
6.2 Field sources
6.3 Introduction to boundary conditions
6.3.1 Patch selection in field files
6.3.2 Geometric constraints
6.3.3 Basic boundary conditions
6.4 Derived boundary conditions
6.4.1 The inlet/outlet condition
6.4.2 Entrainment boundary conditions
6.4.3 Fixed flux pressure
6.4.4 Time-varying boundary conditions
6.5 Field functions in boundary conditions
6.5.1 The functionalFixedValue boundary condition
6.5.2 Parameters as field functions
6.6 Thermal boundary conditions
