You can create a fluid inlet/outlet boundary condition to specify flow conditions at a particular surface location in your model. For more information, see Chapter 30, “Fluid dynamic analyses.”
To create or edit a fluid inlet/outlet boundary condition:
Display the editor using one of the following methods:
To create a new fluid inlet/outlet boundary condition, follow the procedure outlined in “Creating boundary conditions,” Section 16.8.2 (Category: Fluid; Types for Selected Step: Fluid inlet/outlet).
To edit an existing fluid inlet/outlet boundary 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.
To specify momentum based on pressure, click the Momentum tab and do the following:
Toggle on Specify.
Choose Pressure.
Enter the fluid pressure at the inlet or outlet.
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.)
To specify momentum based on velocity, click the Momentum tab and do the following:
Toggle on Specify.
Choose Velocity.
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.)
To specify thermal energy settings, click the Thermal Energy tab and do the following:
Toggle on Temperature, and enter the fluid temperature at the inlet or outlet.
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.)
To specify turbulence settings, click the Turbulence tab.
If you are using the Spalart-Allmaras turbulence model in the current flow step, 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 in the current flow step, 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.
