CFD wind resource analysis with OpenFOAM Reuven Shenkar 2 May 2013 - - PowerPoint PPT Presentation

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cfd wind resource analysis with openfoam
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CFD wind resource analysis with OpenFOAM Reuven Shenkar 2 May 2013 - - PowerPoint PPT Presentation

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CFD wind resource analysis with OpenFOAM Reuven Shenkar 2 May 2013 Mil-OSS conference 1 Motivation Wind resource analysis for wind energy applications Complex terrain induces nonlinear effects Linear models fail

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CFD wind resource analysis with OpenFOAM

Reuven Shenkar

2 May 2013 Mil-OSS conference 1

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Motivation

  • Wind resource analysis for wind energy

applications

  • Complex terrain induces nonlinear effects

Linear models fail

  • Ever-increasing trend towards CFD

Also an increasing need to study turbulence

2 May 2013 Mil-OSS conference 2

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CFD for wind resource

  • Atmospheric boundary layer

Incompressible flow Neglect gravity* Neglect Coriolis Neglect humidity, cloud physics, radiation, aerosols, etc… Do NOT neglect thermal effects = atm. stability

RANS

2 May 2013 Mil-OSS conference 3

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Commercial CFD wind resource codes

  • Dedicated codes

WindSim Meteodyn Ventos …

  • General purpose

Fluent CFX …

2 May 2013 Mil-OSS conference 4

source: www.windsim.com source: www.ansys.com source: www.meteodyn.com
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OpenFOAM – pros & cons

  • Advantages

It’s free! Can run as many cores as you have, no per-core fees Not a black box – full control of the code

2 May 2013 Mil-OSS conference 5

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OpenFOAM – pros & cons (cont’d)

  • Disadvantages

Long and steep learning curve Low productivity Could have been faster Not easy to get support Bugs – especially in esoteric applications

  • However… an ever expanding worldwide users

community (also wind)

Also quite a few commercial vendors offer extensions, training, support etc.

2 May 2013 Mil-OSS conference 6

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OpenFOAM applications

2 May 2013 Mil-OSS conference 7

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OpenFOAM basics

  • OpenFOAM

Meshing (blockMesh, snappyHexMesh) Solvers Postprocessing (paraView & other utilities)

  • Extensions

Open source wrapper scripts (e.g. pyFoam) Commercial GUI available out there

2 May 2013 Mil-OSS conference 8

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Setting up a wind resource analysis case

  • Digital Elevation Model
  • Roughness model
  • Wind data*
  • Stability parameters*

2 May 2013 Mil-OSS conference 9

boundary conditions mesh

source: CFD simulation of the atmospheric boundary layer: wall function problems, Blocken et al. (2007) http://dx.doi.org/10.1016/j.atmosenv.2006.08.019
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Validation cases

  • Askervein Hill
  • Bolund

2 May 2013 Mil-OSS conference 10

source: www.yorku.ca source: www.yorku.ca
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Meshing

  • Pointwise
  • snappyHexMesh

2 May 2013 Mil-OSS conference 11

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Results

  • <mention performance

– run times>

2 May 2013 Mil-OSS conference 12

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Results (cont’d)

2 May 2013 Mil-OSS conference 13

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Challenges

  • Inserting met mast measurements as a point

“boundary condition”

  • Atmospheric stability
  • ABL boundary conditions & turbulence

modeling – still an open issue (like turbulence itself…)

2 May 2013 Mil-OSS conference 14

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Summary

  • OpenFOAM:
  • This, however, comes at a price
  • Test per-application first
  • Expect good/fair performance in common

applications; expect trouble in esoteric applications

  • So far encouraging results

2 May 2013 Mil-OSS conference 15

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2 May 2013 Mil-OSS conference 16

Thanks for listening

reuven.shenkar@rsengineering.co.il

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Hardware and software

  • Binaries for Ubuntu, SuSE, Fedora

www.openfoam.com/www.openfoam.org

Otherwise get source and compile

  • PC

I7-3930K (dual socket Xeon = better) Fast RAM, and lots of it (> 32 GB recommended)

2 May 2013 Mil-OSS conference 17