### 28.1.4. Boundary Details and Fluid Values Tabs for Boundary Condition Objects

The Boundary Details and Fluid Values tabs for a boundary condition object contain settings that specify the values, fluxes, and transfer coefficients of Additional Variables at the boundary condition location. These tabs are accessible, when applicable, by editing a boundary condition object.

The Additional Variables that require specification are those that have been applied to the domain (to which the boundary condition belongs) in a form other than an algebraic equation.

For single phase flow, the Additional Variable settings are on the Boundary Details tab. For multiphase flow, the Additional Variable settings for homogeneous Additional Variables are on the Boundary Details tab and those for fluid-specific Additional Variables are either on the Boundary Details tab or the Fluid Values tab.

The types of boundary conditions that may allow the specification of Additional Variables are:

- `Inlet`

- `Opening`

- `Wall`

- `Outlet`

#### 28.1.4.1. Additional Variables: List Box

This list box is used to select an Additional Variable in order to set the details of its boundary condition specification.

#### 28.1.4.2. Additional Variables: [Name]

##### 28.1.4.2.1. Option

- `Zero Flux`

- `Value`

- `Flux in`

  This option is applicable for Wall boundary conditions and, for Poisson and Diffusive transport models, Inlet boundary conditions.

- `Transfer Coefficient`

- `Wall Flux In`

  This option is applicable for multiphase flow only.

- `Wall Transfer Coefficient`

  This option is applicable for multiphase flow only.

##### 28.1.4.2.2. Value

(applies when Additional Variables: [Additional Variable Name]: Option is set to Value or Transfer Coefficient)

##### 28.1.4.2.3. Flux

(applies when Additional Variables: [Additional Variable Name]: Option is set to Flux in)

##### 28.1.4.2.4. Transfer Coefficient

(applies when Additional Variables: [Additional Variable Name]: Option is set to Transfer Coefficient)

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