### 14.2.2. Boundary Details Tab

Boundary value settings depend on characteristics of the flow. For instance, temperature is required at a boundary only if heat transfer is being modeled.

If you are changing the characteristics of the flow, ensure that boundary conditions are correctly updated. In most cases, CFX-Pre alerts you of the need to update settings in the form of physics validation errors. For details, see Physics Message Window.

Example:

Suppose a domain is created, isothermal flow is specified, and an inlet boundary condition set. If flow characteristics are then altered to include heat transfer, the inlet specification must be changed to include the temperature of the fluid at that location.

More information on some of the settings is available:

- Mass and Momentum in the CFX-Solver Modeling Guide

- Flow Direction in the CFX-Solver Modeling Guide

- Turbulence in the CFX-Solver Modeling Guide

- Heat Transfer in the CFX-Solver Modeling Guide

- Mesh Deformation in the CFX-Solver Modeling Guide

Various settings are available on the Boundary Details tab, depending on the type of boundary condition:

- Boundary Details: Inlet

- Boundary Details: Outlet

- Boundary Details: Opening

- Boundary Details: Wall

- Boundary Details: Symmetry

- Boundary Details: Interfaces

#### 14.2.2.1. Boundary Details: Inlet

##### 14.2.2.1.1. Flow Regime: Inlet

Option can be set to one of `Subsonic`, `Supersonic`, or `Mixed`. For details, refer to the following sections:

- Inlet (Subsonic) in the CFX-Solver Modeling Guide

- Inlet (Supersonic) in the CFX-Solver Modeling Guide

- Inlet (Mixed Subsonic-Supersonic) in the CFX-Solver Modeling Guide

##### 14.2.2.1.2. Mesh Motion: Inlet

The option for Mesh Motion is set to `Stationary` by default. For details, see Mesh Deformation in the CFX-Solver Modeling Guide.

#### 14.2.2.2. Boundary Details: Outlet

##### 14.2.2.2.1. Flow Regime: Outlet

First, specify the flow regime option. For details, refer to the following sections:

- Outlet (Subsonic) in the CFX-Solver Theory Guide

- Outlet (Supersonic) in the CFX-Solver Theory Guide

##### 14.2.2.2.2. Mass and Momentum: Outlet

For details, see Mass and Momentum in the CFX-Solver Modeling Guide.

##### 14.2.2.2.3. Pressure Averaging: Outlet

This option appears when `Average Static Pressure` is selected under Mass and Momentum. For details, see Average Static Pressure in the CFX-Solver Modeling Guide.

##### 14.2.2.2.4. Thermal Radiation: Outlet

For details, see Thermal Radiation in the CFX-Solver Modeling Guide.

##### 14.2.2.2.5. Mesh Motion: Outlet

The option for Mesh Motion is set to `Stationary` by default. For details, see Mesh Deformation in the CFX-Solver Modeling Guide.

#### 14.2.2.3. Boundary Details: Opening

##### 14.2.2.3.1. Mass and Momentum: Opening

For details, see Mass and Momentum in the CFX-Solver Modeling Guide.

##### 14.2.2.3.2. Flow Direction: Opening

This option appears when a flow direction is required; that is, when one of `Opening Pres. and Dirn.` or `Static Pres. and Dirn.` is selected under Mass and Momentum. For details, see Flow Direction in the CFX-Solver Modeling Guide.

##### 14.2.2.3.3. Loss Coefficient: Opening

For details, see Loss Coefficient in the CFX-Solver Modeling Guide

##### 14.2.2.3.4. Turbulence: Opening

For details, see Turbulence in the CFX-Solver Modeling Guide.

##### 14.2.2.3.5. Heat Transfer: Opening

For details, see Heat Transfer in the CFX-Solver Modeling Guide.

##### 14.2.2.3.6. Thermal Radiation: Opening

This is the same as specifying thermal radiation at an inlet. For details, see Thermal Radiation in the CFX-Solver Modeling Guide.

##### 14.2.2.3.7. Component Details: Opening

The Component Details section appears when a variable composition/reacting mixture has been created for a single phase simulation, or a simulation with one continuous phase and particle tracking.

The mass fractions must sum to unity on all boundaries. With this in mind, highlight the materials you want to modify and enter the mass fraction. To enter an expression for the mass fraction, click Enter Expression and enter the name of your expression.

##### 14.2.2.3.8. Mesh Motion: Opening

The option for Mesh Motion is set to `Stationary` by default. For details, see Mesh Deformation in the CFX-Solver Modeling Guide.

#### 14.2.2.4. Boundary Details: Wall

##### 14.2.2.4.1. Mass And Momentum: Wall

Option can be set to one of `No Slip Wall`, `Free Slip Wall`, `Finite Slip Wall`, `Specified Shear`, `Counter-rotating Wall`, `Rotating Wall` or `Fluid Dependent`. For details, see Mass and Momentum in the CFX-Solver Modeling Guide.

###### 14.2.2.4.1.1. Slip Model Settings

The Slip Model settings apply for finite slip walls.

The only available option is `Power Law`. You must provide the nominal slip speed (Us ), the critical stress (), the slip power (m), the pressure coefficient (B), and the normalizing stress ().

For details about the finite slip wall model, see Finite Slip Wall in the CFX-Solver Modeling Guide.

###### 14.2.2.4.1.2. Shear Stress Settings

The Shear Stress settings apply for walls with specified shear.

You specify the shear stress value directly, using a vector that points tangentially to the wall. The normal component of the vector that you specify is ignored.

###### 14.2.2.4.1.3. Wall Velocity Settings

The Wall Velocity settings apply for no slip walls, and walls with finite slip.

The Wall Velocity Relative To option can be used to set the wall velocity relative to either the `Boundary Frame` or `Mesh Motion` occurring on the boundary. You can select only the `Boundary Frame` option if the wall mesh motion is set to either `Unspecified`, `Parallel to Boundary` or `Surface of Revolution`. For details about no slip wall velocity, see No Slip Wall in the CFX-Solver Modeling Guide.

If Wall Velocity > Option is set to `Cartesian Components`, you must specify the velocity in the X, Y, and Z axis directions. Similarly, if you choose `Cylindrical Components` then values are required for Axial Component, Radial Component, and Theta Component.

You can specify a counter rotating wall. For details, see Counter-rotating Wall in the CFX-Solver Modeling Guide.

Specifying a `Rotating Wall` requires an angular velocity and, if the domain is stationary, an axis definition. For details, see Rotating Wall in the CFX-Solver Modeling Guide.

###### 14.2.2.4.1.3.1. Axis Definition

If you select `Coordinate Axis`, a Rotation Axis is required. The `Two Points` method requires a pair of coordinate values specified as Rotation Axis From and Rotation Axis To.

##### 14.2.2.4.2. Wall Roughness

For details, see Wall Roughness in the CFX-Solver Modeling Guide.

##### 14.2.2.4.3. Solid Motion: Wall

If the boundary is for a domain that involves solid motion, then the Solid Motion > Boundary Advection option may be available. If the velocity for the solid motion (specified in the Boundary Details tab for the domain) is directed into the domain everywhere on a boundary, and if you specify a fixed temperature or a fixed value of an Additional Variable on that boundary, then you should consider turning on the Boundary Advection option.

If you have specified a fixed temperature, then turning on the Boundary Advection option causes the advection of thermal energy into the solid domain at a rate that is consistent with the velocity normal to the boundary, the specified fixed temperature, and the material properties.

If you have specified a fixed value for an Additional Variable, then turning on the Boundary Advection option causes the advection of that Additional Variable into the solid domain at a rate that is in accordance with the velocity normal to the boundary, the specified fixed value of the Additional Variable, and, for mass-specific Additional Variables, the density of the solid material.

For a boundary where the solid is moving out of the domain, consider turning on the Boundary Advection option in order to allow thermal energy and Additional Variables to be advected out.

For details on setting up the solid motion model for a domain, see Solid Motion. For details on Additional Variables, see Additional Variables.

##### 14.2.2.4.4. Heat Transfer: Wall

For details, see Heat Transfer in the CFX-Solver Modeling Guide.

##### 14.2.2.4.5. Fluid Pairs: Wall

For details on the wall boiling model, see Wall Boiling Model in the CFX-Solver Modeling Guide.

##### 14.2.2.4.6. Wall Contact Model

For details, see Wall Contact Model in the CFX-Solver Modeling Guide.

##### 14.2.2.4.7. Thermal Radiation: Wall

For details, see Thermal Radiation in the CFX-Solver Modeling Guide.

##### 14.2.2.4.8. Mesh Motion: Wall

The option for Mesh Motion is set to `Stationary` by default. For details, see Mesh Motion in the CFX-Solver Modeling Guide.

##### 14.2.2.4.9. Additional Coupling Sent Data

This setting is available for ANSYS Multi-field runs. For details, see Additional Coupling Sent Data in the CFX-Solver Modeling Guide.

#### 14.2.2.5. Boundary Details: Symmetry

Only Mesh Motion can be set in this tab for Symmetry boundary conditions. The option for Mesh Motion is set to `Unspecified` by default. For details, see Mesh Deformation in the CFX-Solver Modeling Guide.

#### 14.2.2.6. Boundary Details: Interfaces

The options for Mass and Momentum, Turbulence, Heat transfer, Mesh Motion, and Additional Variables are set to `Conservative Interface Flux` by default.

Important: `Conservative Interface Flux` implies that the quantity in question will “flow” between the current boundary and the boundary on the other side of the interface. This means that `Conservative Interface Flux` must also be used on the boundary on the other side of the interface. Accordingly, the CFX-Solver will not be able to handle cases where `Conservative Interface Flux` is set on just one side of the interface, or where the quantity being transferred does not exist on the other side. CFX-Pre will issue a warning if either of these cases exist.

For details on Nonoverlap Conditions, refer to Non-overlap Boundary Conditions.

#### 14.2.2.7. Mesh Motion

When mesh deformation is selected for the domain that contains a boundary condition, mesh motion can be specified for the boundary on the Boundary Details tab.

The available options are:

- `Conservative Interface Flux`

- `Unspecified`

- `Stationary`

- `Specified Displacement`

- `Specified Location`

- `Periodic Displacement`

- `Parallel to Boundary`

- `Surface of Revolution`

- `ANSYS MultiField`

- `Rigid Body Solution`

For details on these options, see Mesh Motion Options in the CFX-Solver Modeling Guide.

For details on mesh deformation, see Mesh Deformation in the CFX-Solver Modeling Guide.

See Mesh Deformation for information about activating mesh deformation for the domain.

#### 14.2.2.8. Electric Field

When an electric field model is activated for a domain that contains a boundary condition, Electric Field can be specified for a boundary from the Boundary Details tab.

The available options are:

- Voltage

- Ground

- Flux In

- Zero Flux

- Electrical Current Transfer Coefficient

- Conservative Interface Flux

- Electric Field Contact Resistance

For details, see Electric Field in the CFX-Solver Modeling Guide.

For information about activating an electric field model for a domain, see Electromagnetic Model.

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