| dc.description.abstract | Simulation software is increasingly replacing traditional physical
testing in the process of product development, as it can in many cases
reduce development times and costs. In a variety of applications, the
reduction of noise is an important aspect of the product design and
using methods from the field of computational aero-acoustics (CAA),
the generation and propagation of sound in air may be simulated.
In this project, a FEM-based solver for the three-dimensional Helmholtz
equation, modeling the propagation of sound waves, has been
developed and tested. The implementation includes Galerkin/leastsquares
stabilization. Both interior and exterior problems are handled;
the latter by a coupled finite-infinite element method. Further,
using a hybrid CAA methodology the solver may be coupled to a CFD
solver, to simulate the sound arising from transient fluid flows.
The solver has been tested, and observed to perform well, on a set
of interior and exterior problems. Results are presented for three cases
of increasing complexity: first an interior, homogeneous problem with
a known analytical solution, second an exterior problem with point
sources and third an exterior problem with acoustic sources from a
CFD computation, i.e. a full hybrid CAA simulation. In the two latter
cases, the frequencies at which standing waves appear in a pipe and
a deep cavity, respectively, are compared to theoretically computed
values, and are seen to be well captured by the simulations. Moreover,
the results of the full CAA simulation are compared to experimental
data, to which they show good resemblance.
The mathematical model, numerical methods and implementation
are presented in the report along with numerical results. | sv |
