Prescribed Displacement
The Prescribed Displacement node adds a condition where the displacements are prescribed in one or more directions to the porous matrix boundary.
If a displacement is prescribed in one direction, this leaves the porous matrix free to deform in the other directions. Also define more general displacements as a linear combination of the displacements in each direction.
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If a prescribed displacement is not activated in any direction, this is the same as a Free constraint.
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If a zero displacement is applied in all directions, this is the same as a Fixed Constraint for the porous matrix and a Sound Hard Wall for the fluid.
Prescribed Displacement
Define the prescribed displacements using a Standard notation or a General notation.
Standard Notation
To define the displacements individually, click the Standard notation button (the default).
To define a prescribed displacement for each space direction (x, y, and z for 3D), select one or more of the Prescribed in x direction, Prescribed in y direction, and Prescribed in z direction check boxes. Then enter a value or expression for the prescribed displacements u0, v0, or w0 (SI unit: m).
For 2D axisymmetric components and to define a prescribed displacement for each space direction (r and z), select one or both of the Prescribed in r direction and Prescribed in z direction check boxes. Then enter a value or expression for the prescribed displacements u0 or w0 (SI unit: m).
General Notation
To specify the displacements using a General notation that includes any linear combination of displacement components, click the General notation button.
Enter values in the H matrix and R vector fields. For the H matrix, also select an Isotropic, Diagonal, Symmetric, or Full matrix and enter values as needed.
Constraint Settings
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box.
Prescribed Displacement Equations