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fixedPointLoadFvPatchVectorField

Description

The fixedPointLoad boundary condition applies a fixed point load to a patch. The specified force is distributed over the boundary faces closest to the user-defined point. This BC is useful for simulating localized forces acting on specific regions of a boundary, trying to replicate FEM boundary conditions that apply the force on a single node.

The user specifies the location of the point and the magnitude of the force in the boundary dictionary. If the force magnitude is set to zero, the simulation will terminate with an error.

Options

The fixedPointLoad fvPatchField can be selected in the patch subdictionary inside the boundaryField subdictionary of the displacement field.

Parameters in the patch subdictionary for fixedPointLoad:

point Vector specifying the location of the point in meters.
force Vector specifying the magnitude and direction of the applied force in N. The force is distributed over the faces closest to the specified point.
pressure (Optional) Initial pressure field for restart simulations.

Parameters in the patch subdictionary derived from tractionDisplacement:

fixedSpring Activates a fixed spring-dashpot system for additional stability. Default: false.
fixedSpringModulus Spring modulus in N/m. Required when fixedSpring is set to true.
dashpotModulus Dashpot modulus in N/m. Required when fixedSpring is set to true.
planeStrain Activates the plane strain approximation for the normal stress at the boundary. When enabled, the normal strain is assumed constant across the last layer of cells. Default: false.
relax Relaxation factor for gradient updates. Default: 1.0.
value Initial displacement value (not stress).

Usage

To apply the fixedPointLoad boundary condition to a given patch, you need to specify its typename in the patch definition in the boundary condition file (e.g., 0/D or 0/DD for simulations involving incremental mechanical solvers).

Example: Applying fixedPointLoad to the loadBoundary patch:

loadBoundary
{
    type            fixedPointLoad;

    // Location of the point in meters
    point           (0.5 0.5 0);

    // Magnitude and direction of the applied force in N
    force           (0 0 -100);

    // (Optional) Initial pressure field for restart simulations
    pressure        uniform 0;

    // Activate plane strain approximation (default is false)
    planeStrain     false;

    // Relaxation factor for the gradient update
    relax           1.0;

    // Initial displacement value
    value           $internalField;
}