MESHING 
ATILA requires that the mesh be composed exclusively of
second order elements. The corre-sponding setting can be
found under the Meshing menu. Select Quadratic Elements,
then Quadratic. Note that this option is automatically
set when you open the ATILA-GiD interface.
We will create mix of structured rectangles
mesh and unstructured triangle mesh. Note that such mixing
of
element types in GiD is currently only available in
2D. Also note that only four-sided surfaces can be structured.
First, we define the structured mesh. Select Meshing | Structured | Surfaces.
Apply this meshing condition to the piezoelectric surfaces.
GiD then requests further information
about the number of subdivisions that should be applied
to lines (this will structure the mesh). Select 6 mesh
subdivisions and apply to all the lines.
Because the remainder of the geometry is meshed automatically,
proceed by selecting Meshing | Generate. Apply a
default size value of 1.9 for the automatic mesh (in the
same units as the rest of the model).
When GiD has terminated the mesh generation,
a window is displayed with information about the number
of elements that
were generated. The mesh is shown in the next figure.
Note that the mesh depends on your
settings. To access the settings, select Preferences
from the Utilities menu,
then open the Meshing tab. The settings used to
produce the mesh of this tutorial are shown below.
Note that we desire to produce a fine mesh here, because
it will be desired to compute stresses in the transducer.
Stresses are obtained as first derivative of the finite element
problem unknowns (displacements). For these derivatives to
be evaluated correctly, a dense mesh is required.
MESHING
(Water) 
The mesh can be immediately generated.
Previous definitions of the structured mesh are still
pre-sent in the model. The new water domain will be meshed
automatically. The mesh below was obtained with a default
element size set to 1.9.