The following points are important to note during remeshing:
The total mesh displacement variable is relative to a specific mesh topology. Because the mesh topology changes, this variable is reset each time remeshing occurs.
The new variable called
total centroid displacementtracks the displacement of each boundary’s centroid since the beginning of the analysis (that is, relative to the original mesh).The specified displacement based mesh motion is relative to the initial mesh and must therefore include an offset to account for mesh re-initialization. The
Mesh Initialisation Timevariable corresponds to the time at which mesh re-initialization last occurred. This can be used to evaluate the required offset for time varying mesh displacement.
Note: Total Centroid Displacement is the
sum of total mesh displacement and an offset vector. The value of
the offset is determined by the displacement of the boundary’s
centroid from its original position to its initial position. When
using Total Centroid Displacement in a non-remeshing
case, the original and the initial position are the same, resulting
in an offset value of zero. In this case, there seems to be no difference
between the variables, Total Centroid Displacement and Total Mesh Displacement. However, when
using Total Centroid Displacement in a remeshing
case, the original position is defined at the start of the simulation,
while the initial position is defined after the last remesh; this
results in an offset contribution that is non-zero.
An example of the expressions used to evaluate an applied displacement
that includes the required offset to account for mesh re-initialization
is given below. In this example, the applied displacement is evaluated
as the desired displacement minus the value of the desired displacement
at the Mesh Initialisation Time.
Disp Desired = 1[m]*0.5*(1-cos(2.[s^-1]*pi*t)) Disp Mesh ReInit = 1[m]*0.5*(1-cos(2.[s^-1]*pi*Mesh Initialisation Time )) Disp Applied = Disp Desired - Disp Mesh ReInit