You can create a fluid wall boundary condition to prescribe a no-slip, shear, or infiltration boundary condition for the fluid at a wall boundary. For more information, see Chapter 30, “Fluid dynamic analyses.”
To create or edit a fluid wall boundary condition:
Display the fluid wall condition editor using one of the following methods:
To create a new fluid wall condition, follow the procedure outlined in “Creating boundary conditions,” Section 16.8.2 (Category: Fluid; Types for Selected Step: Fluid wall condition).
To edit an existing fluid wall condition using menus or managers, see “Editing step-dependent objects,” Section 3.4.13. To edit the region to which the boundary condition is applied, see “Editing the region to which a prescribed condition is applied,” Section 16.8.4.
From the Condition options, do one of the following:
Choose No slip to create a no-slip, no-penetration surface where the fluid adheres to the wall without penetrating it.
Choose Shear to create a slip wall where the fluid does not adhere to the wall but cannot penetrate it.
Choose Infiltration to create an infiltration wall where fluid can penetrate the surface while maintaining the no-slip condition.
If you are defining a No slip boundary condition, specify the following conditions as required:
Velocity
The velocity components are automatically set to zero.
Thermal Energy
Thermal energy settings are applicable only if you are using a temperature-based energy equation in the current flow step. To specify thermal energy settings, click the Thermal Energy tab and do the following:
Toggle on Specify, and choose Temperature or Heat flux.
In the Magnitude field, specify the temperature or heat flux value.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click 
to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Turbulence
Turbulence settings are applicable only if you are using a turbulence model in the current flow step.
If you are using the Spalart-Allmaras turbulence model, the eddy viscosity and the normal distance boundary condition are set to zero.
If you are using the k–
RNG turbulence model, the normal distance boundary condition is set to zero.
If you are defining a Shear boundary condition, specify the following conditions as required:
Velocity
To specify velocity conditions, click the Velocity tab and do the following:
By default, the global coordinate system is used to define the boundary condition.
You can select another coordinate system in which to specify the boundary condition; only a rectangular coordinate system can be selected. To avoid precision loss due to finite precision arithmetic, you must enter values for all three components when applying fluid velocity boundary conditions in a coordinate system other than the global coordinate system. Abaqus/CAE transforms these values and applies them in the global coordinate system.
Click 
for the CSYS option, and do one of the following:
Select an existing datum coordinate system in the viewport.
Select an existing datum coordinate system by name.
From the prompt area, click Datum CSYS List to display a list of datum coordinate systems, select a name from the list, and click OK.
Click Use Global CSYS from the prompt area to revert to the global coordinate system.
Alternatively, click 
to define a new datum coordinate system.
This coordinate system editing option is available only in the step in which the boundary condition is created.
Click the arrow to the right of the Distribution field, and select the option of your choice from the list that appears:
Select Uniform to define a fluid boundary condition that is uniform over the region.
Select an analytical field to define a spatially varying fluid boundary condition. Only analytical fields that are valid for this boundary condition type are displayed in the selection list. Alternatively, you can click 
to create a new analytical field. (See Chapter 58, “The Analytical Field toolset,” for more information.)
Toggle on the degrees of freedom that you want to specify, and enter the velocity values. If you are applying the boundary condition in a coordinate system other than the global coordinate system, you must enter values for all of the velocity components.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Thermal Energy
Thermal energy settings are applicable only if you are using a temperature-based energy equation in the current flow step. To specify thermal energy settings, click the Thermal Energy tab and do the following:
Toggle on Specify, and choose Temperature or Heat flux.
In the Magnitude field, specify the temperature or heat flux value.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Turbulence
Turbulence settings are applicable only if you are using a turbulence model in the current flow step.
If you are using the Spalart-Allmaras turbulence model, the eddy viscosity and the normal distance boundary condition are set to zero.
If you are using the k– RNG turbulence model, the normal distance boundary condition is set to zero.
If you are defining an Infiltration boundary condition, specify the following conditions as required:
Velocity
To specify velocity conditions, click the Velocity tab and do the following:
By default, the global coordinate system is used to define the boundary condition.
You can select another coordinate system in which to specify the boundary condition; only a rectangular coordinate system can be selected. To avoid precision loss due to finite precision arithmetic, you must enter values for all three components when applying fluid velocity boundary conditions in a coordinate system other than the global coordinate system. Abaqus/CAE transforms these values and applies them in the global coordinate system.
Click for the CSYS option, and do one of the following:
Select an existing datum coordinate system in the viewport.
Select an existing datum coordinate system by name.
From the prompt area, click Datum CSYS List to display a list of datum coordinate systems, select a name from the list, and click OK.
Click Use Global CSYS from the prompt area to revert to the global coordinate system.
Alternatively, click to define a new datum coordinate system.
This coordinate system editing option is available only in the step in which the boundary condition is created.
Click the arrow to the right of the Distribution field, and select the option of your choice from the list that appears:
Select Uniform to define a fluid boundary condition that is uniform over the region.
Select an analytical field to define a spatially varying fluid boundary condition. Only analytical fields that are valid for this boundary condition type are displayed in the selection list. Alternatively, you can click to create a new analytical field. (See Chapter 58, “The Analytical Field toolset,” for more information.)
Toggle on the degrees of freedom that you want to specify, and enter the velocity values. If you are applying the boundary condition in a coordinate system other than the global coordinate system, you must enter values for all of the velocity components.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Thermal Energy
Thermal energy settings are applicable only if you are using a temperature-based energy equation in the current flow step. To specify thermal energy settings, click the Thermal Energy tab and do the following:
Toggle on Specify, and choose Temperature or Heat flux.
In the Magnitude field, specify the temperature or heat flux value.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Turbulence
Turbulence settings are applicable only if you are using a turbulence model in the current flow step.
If you are using the Spalart-Allmaras turbulence model, the normal distance boundary condition is set to zero. In addition, do the following:
Toggle on Kinematic eddy viscosity, and enter the kinematic eddy viscosity for the fluid.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
If you are using the k– RNG turbulence model, the normal distance boundary condition is set to zero. In addition, do the following:
Toggle on Turbulent kinetic energy; and enter the turbulent kinetic energy, k, for the fluid.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Toggle on Dissipation rate; and enter the dissipation rate, , for the fluid.
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click to create a new amplitude.
Click OK to save your data and to exit the editor.
