globalwindgroup.com
Evan Greer,
Mentor: Dr. Marcelo Kobayashi,
HARP REU Program
August 2, 2012
Contact: evantk@hawaii.edu
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Introduction and Motivations
Creating the geometry
Stationary study of turbine geometry
Rotating study of turbine geometry
Future Plans
Acknowledgements
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Energy Security
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High reliability of fossil fuels leads to wide
spread use
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Set amount of fossil fuel outputs a set
amount of energy
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Introduction of reliability to renewable
resources, wind energy in particular
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Wind energy is subject to low reliability due
to changing weather conditions
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Scale predictions of large scale weather
patterns to make predictions about the
environment around the turbine
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The effects of local topography on efficiency
will be studied
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WRF (weather research and forecasting)
model coupled with CFD models
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This is the future goal of this research but first
a working model of the turbine must be
created and studied
Used a sample geometry from
Comsol Multiphysics
 Played with initial conditions
and mesh sizes
 Learned how to use the Comsol
Multiphysics software
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 Studied introductory tutorial
building a busbar geometry
 Learned how to set up fluid flow
and thermoelectric physics
• Approximated the geometry of a
typical wind turbine
• Height of the tower set at 300 ft
•Length of the rotors set at 200 ft
•Length of the nacelle set at 40 ft
Front View
Side View
• Created for the
implementation of the sliding
mesh
• Cylindrical region with a
height of 80 ft encompassing
the blades
• Domain to move with the
blades
• Region where boundary
and initial conditions are to
be defined
• Created a cylindrical
region behind the sliding
region to study wake
• Material for the flow set
as air and material for
turbine set as aluminum
• Generated mesh using
tetrahedral elements
•Mesh had to be refined
around blades
•Mesh consisted of 93349
elements
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Ran a stationary turbulent flow study using a
k-ε model
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This model has the purpose of understanding
how fluid flow is affected by geometry
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Used a simple turbulent flow physical model
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Stationary study step with no time
dependence
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Inlet velocity of 3.219 m/s, this is the average
annual wind speed of Honolulu reported by
NOAA [1]
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Outlet condition was also set to atmospheric
pressure
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Also, a volume force was introduced on the
flow domain
 Used Rotating Machinery,
Turbulent Flow physical model
 Moving domains are coupled
with stationary domains by
identity pairs
 At these identity pairs, a flux
continuity boundary condition
is applied
 Navier-Stokes equations are
formulated based on rotating
and stationary coordinate
systems
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Convergence of time stepped solution
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Solution would get stuck on calculation of
time step
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Many issues with script files and runs on
supercomputer
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Issues with licensing
 Jobs would terminate because of lack of licensing on
multiple nodes
 Solved with batch and cluster computing add-on to
job configurations within Comsol
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Issues with node communication
 Comsol would get kicked nodes
 Solved using MPD (Multi processing Daemon) used by
Comsol to communicate between nodes
 Accomplished through modification of script files with
the help of Andrew Yukitomo
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Isolated rotating
geometry
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Try to get rotating
blade working
without pairing
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Added input and
output condition
 Added pairing and flow
continuity condition
between stationary and
rotating domains
Used overlapping domains
and input and output
conditions
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Used non-overlapping
domains
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Got rid of input and output
conditions, instead used a
pressure point constraint
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Increased number of
iterations used by the solver
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Complete the set up of the full rotating
geometry
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Get the blade study to run for larger time scales
 Further work needs to be done to understand where
and why the convergence errors are occurring
 Understanding how to make a more accurate mesh
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Introduce the stationary wake region and a two
dimensional pairing region
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Introduce the flow domain and three
dimensional pairing and get the complete
model to run
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Get the rotation of the turbine to be dictated
by inlet velocity conditions
 This will involve delving deeper into the interface
to understand how to program physical models
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Project benchmarks:
 Creating geometry
 Modeling stationary case
 Implementation of sliding mesh
 Implementation of Large Eddy Simulation
 Implementation of WRF data
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This research will be continued under a NASA
space grant in the fall
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I would like to thank Dr. Susan Brown for giving me
the opportunity to be a part of this program and Dr.
Marcelo Kobayashi for his continued support and
allowing me to share in his research. I also want to
acknowledge Andrew Yukitomo for his continued help
with script files and supercomputing issues and HOSC
for allowing us to use the supercomputing facilities for
our work.
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"This material is based upon work supported by the National Science
Foundation under Grant No. 0852082. Any opinions, findings, and
conclusions or recommendations expressed in this material are those of the
author(s) and do not necessarily reflect the views of the National Science
Foundation."
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[1] Delliger, Dan, 2008, Average Wind Speed, Comparative Climate Data,
http://lwf.ncdc.noaa.gov/oa/climate/online/ccd/avgwind.html (July 5, 2012)
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[2] Laminar Flow in a Baffled Stirred Mixer. Comsol Multiphysics 4.3 sample
program documentation, 2012