Boundary: Nodal Head

Function

Assign nodal head. Nodal head value for both steady state and transient state can be defined using this function. For nodal head variation, please refer to the example below.

Call

Model > Boundary > Nodal Head

BC Set

Select a Boundary Set in which the specified boundary condition is included
Click to the right to prompt the Define Boundary Set dialog box to add, modify or delete the Boundary Sets. If the user types the name of the Boundary Set directly in the entry box, GTS will automatically create the relevant Boundary Set.

Object

Type

Select a method for selecting a part where the nodal head will be assigned.

Curve

Select Curves on which the boundary condition will be applied.

Surface

Select Surfaces on which the boundary condition will be applied.

Node

Select the nodes directly.

Free Face Node

Select the nodes on the free faces of the selected element. All nodes within the defined angle (Feature Angle) from a seed node will be assigned.

Free Face Node

It becomes active when selecting Free Face Node selection method is designated.

Seed Node

Select a Seed Node which becomes the reference of determining free face.

Feature Angle

When it expands out the free face selection from the Seed Node, it only select element nodes within the specified Feature Angle.

Click to select free face nodes and they will appear on the screen.

Mode

Add

Add/Modify nodal head value on selected nodes.

Delete

Delete nodal head value on selected nodes.

Apply to Unassigned Objects Only

When adding new nodal head value, this option applies nodal head value only to the unassigned nodes.

Nodal Head

Nodel Head values are referenced with respect to the GCS

Value

Enter the nodal head value.

Type

Select a type of nodal head. Two options are provided - Total Head and Pressure Head.

Function

If the nodal head is defined using a function, select the relevant function. If the nodal head has not been created yet, click button to invoke the Create/Modify Function dialog box.

Review Boundary based on Seepage Conditions

This option enables the user to check nodal head condition as the water level changes in the analysis model.

Example: Nodal Head Variation

Simple example on how to apply varying water head levels directly to the geometry.

Height: Left Side 328 ft

Height Right Side 131 ft

1. Model > Boundary > Nodal Head

2. Select Object Type as "Curve."

If the curve is not detected, ensure that the geometry is not hidden.

3. Select Nodal Head as Type "Pressure" with value set to 0.

4.Click [OK].

5. From Pre-Works > Boundary and explode the tree until "Curve" is shown. Call the context menu, by Right clicking the and then call "Transfer to FE" to transfer information from geometry to respective nodes.

Note: The nodal head levels will be automatically calculated after the model has completed an analysis. Therefore, correct nodal head levels can be obtained by calling the "Table" from the Post-Works ie Total Head.

Nodal head values pertaining to each node will only show that the pressure head = 0 if called from pre-works tree.

Pre-Works table:

Post-Works table: