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Nicole M. Diana, FLUENT Product Market Manager, Fluent Inc.
Three UDF-based add-on modules have been developed for use with FLUENT
6.0. All three modules handle complicated geometry efficiently using
unstructured grids, and are accessible through the graphical user interface.
The modules have been subjected to the same level of testing as FLUENT
6.0, and full documentation and technical support are available.
Contours of the surface dipole strength are shown on the top and bottom
surfaces of a blunt flat plate, as predicted by the flow-induced noise
model in FLUENT
Flow-induced noise prediction
The noise generated by flows across the surface of an obstruction can
be computed using the noise prediction module. This capability can be
applied to the simulation of flow-induced noise in many industries. Some
examples include noise generated by air flowing past the exterior mirror
of a moving automobile and noise generated by the flow over landing gear
attached to an airframe. Based on a transient turbulent flow simulation,
the time variation of the acoustic pressure together with the sound pressure
level (SPL) are calculated using Lighthill’s Acoustic Analogy. The
large eddy simulation (LES) turbulence model is highly recommended for
this purpose, since it can capture the wide band sound spectrum. The model
predicts the power spectrum and surface dipole strength distribution.
Results for flow across a flat plate are in good agreement with experiment
data.
A comparison of FLUENT MHD predictions with measurements of normalized
steel velocity as a function of imposed magnetic field at the meniscus
of a steel mold. In the simulation, the meniscus velocity changes its
direction slowly with increasing field strength, whereas in the experiment,
the meniscus velocity changes its direction more rapidly. The sudden change
in the actual casting process is due to the effects of injected argon
gas, and these effects were not included in the simulation.
Magnetohydrodynamic modeling
The interaction between an applied electromagnetic field and an electrically
conductive fluid can be analyzed using the magnetohydrodynamics (MHD)
module. This capability can be applied to the continuous casting of steel
or aluminum, for example. The model, an upgrade of the MHD model in FLUENT
4, simulates the flow under the influence of either constant or oscillating
electromagnetic fields. A prescribed magnetic field can be generated
by selecting simple built-in functions or by importing a user-supplied
data file. Coupling between the flow and the magnetic field is modeled
through the induced current (due to the movement of conducting material
in the magnetic field), and the effect of the Lorentz (J x B) force as
a source term in the momentum equations. The capability is compatible
with both the discrete phase and volume of fluid models. The effect of
the discrete phase on the electrical conductivity of the mixture can also
be included.
Continuous fiber modeling
In the fiber spinning process, molten polymer is extruded through a
spinneret, which normally contains hundreds of holes, to form multiple
fibers. The fibers are then solidified and drawn down in a quenching
chamber. The final fiber strength and quality is strongly influenced by
the gas flow field surrounding the fibers, including the rate of convective
cooling or heating and the concentration of the gases within the quenching
chamber. The fiber module in FLUENT 6.0 is an upgrade to the model that
originally appeared in FLUENT 4. It includes the effect of numerous fibers
with complete coupling between the fibers and gas flow. Gravity effects,
friction with the surrounding gas, as well as heat and mass transfer are
included. The model predicts the effect of fiber motion on the flow field
as well as the fiber temperatures in the quench box.
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