Wave2000 Example #5:
Focussed (phased) array source transducer and infinite boundary conditions.
In this example of a Wave2000 simulation, a demonstration is given of a focussed
source array in a 20 mm wide x 24 mm high water bath. It also displays Wave2000's "infinite
boundary condition" feature.
Wave2000 has phased arrays, even allowing arbitrary phasing or delays. In
this example, a focussed 2.4 cm long source array located on the left edge
of the water bath (shown in the figure below as a thin blue line with a grey
backing) with focal length 10 mm emits a 1MHz sine Gaussian longitudinal pulse.
It is received by two "point" (i.e., very short) receivers (much like 2 hydrophones)
both located 10 mm from the left side of the water bath. One receiver is located
at the focus itself (in the center of the water bath) while the other receiver
is located 3 mm (laterally) below the focus. The figure below also shows three
(3) infinite boundary conditions (denoted by the green borders), located on
the top, bottom and right side of the water bath, respectively.
Wave2000 has infinite boundary conditions. As may be seen below,
the array generates a wavefront which focusses at the center of the water tank.
Note also that the wave does not reflect from the edge of the water tank, but
simply "disappears" as if it were propagating off into an "infinite" size water
tank. This avoids the need to "window out" reflections from the tank boundaries
when analyzing the data.
Receiver (hydrophone-like) measurements are easy to make. As
may be seen, the displacement at the receiver located 3 mm below the focus
(appearing as blue and labeled as "L - focus + 3mm") is much less than that
at the receiver located in the focal point of the source array (appearing as
red and labeled as "L - focus"). Also shown is the source waveform (appearing
as green and labeled as "L - Left Long. (Source)").
Setting up the phased array parameters are simple in Wave2000.
The figure below shows the Wave2000 Source Array Configuration page for setting
up the array parameters. A similar page exists for defining a receiver array
This example displays Wave2000's ability to generate phased array behavior.
The program allows the user to set a deflection angle and/or focal length,
as well as to adjust element size and spacing. The program accounts for all
aspects of the acoustic wave propagation problem, with no need for any simplifying
assumptions. Wave2000 allows you to explore a whole host of configurations
and determine the effects of an almost unlimited number of variables on the
propagating ultrasound wave and on the receiver measurements.