Investigation of GAO-YONG turbulence model with OpenFOAM


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A new conception turbulence model with partial average.

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Investigation of GAO-YONG turbulence model with OpenFOAM

  1. 1. Investigation ofGao-Yong turbulence model with OpenFOAM<br />Haibin LI<br /><br />25/05/09<br />
  2. 2. Abtract<br />In this talk, a relatively newturbulence model named Gao-Yongturbulence model is investigated using the open source software—OpenFOAM. A newly developed statistical partial average scheme is presented. As the ensemble average is taken on two groups of turbulent fluctuations separately, the partial average scheme able to capture the first-order statistical moment of the fluctuation field, providing valuable information in addition to what have been known in the past from the conventional Reynolds average. Without any empirical coefficients, the derived equations can be used to simulate statistical mean behaviours and coherent structures of various benchmark turbulent flows. The simulated results are in good agreement with experimental data.<br />5/22/2009<br />2<br /><br />
  3. 3. Content<br /><ul><li>Turbulence model
  4. 4. Gao-Yong turbulence model
  5. 5. The deriving process of Gao-Yong turbulence model
  6. 6. Ensemble average
  7. 7. Partial average
  8. 8. Open source software - OpenFOAM
  9. 9. The simulated examples</li></ul>5/22/2009<br />3<br /><br />
  10. 10. Turbulence Model<br /><ul><li>What – the conception
  11. 11. Why – the significance
  12. 12. How – the current methods</li></ul>5/22/2009<br />4<br /><br />
  13. 13. Turbulence<br /><ul><li>Conception:Turbulence or turbulent flow is a fluid regime characterized by chaotic, stochastic property changes.--wikipedia
  14. 14. No exact defination.
  15. 15. Renolds Experiment</li></ul>5/22/2009<br />5<br /><br />
  16. 16. Introduction<br /><ul><li>Open Source Software has many advantages
  17. 17. Vitality </li></ul>Never rise price, stop development or technical support due to business problem<br /><ul><li>Quality</li></ul>Bug track and fix by global members of open community <br />Necessary for scientific computing software. <br />Black box verification can not fully demonstrate the validity especially for non-linear science software.<br /><ul><li>Creativity</li></ul>Innovative research might change the codes at any level.<br />5/22/2009<br />6<br /><br />
  18. 18. GAO-YONG TURBULENCE EUQTIONS<br /><ul><li>Based on partial average, modeling, rational deriving
  19. 19. No any adjustable empirical coefficients
  20. 20. Do not need wall function
  21. 21. Some steady numerical examples</li></ul>5/22/2009<br />7<br /><br />
  22. 22. GAO-YONG TURBULENCE EUQTIONS<br />Define the partial average of the fluctuations as:<br />Where<br />5/22/2009<br />8<br /><br />
  23. 23. GAO-YONG TURBULENCE EUQTIONS<br />Applying the partial average to fluctuation equations we will get equations<br />Model<br />We also have continuity equation: <br />5/22/2009<br />9<br /><br />
  24. 24. GAO-YONG TURBULENCE EUQTIONS<br />Suppose that the constitutive relationship still exists along the direction of mean flow velocity . <br />In coordinate system 123 constituted by ,<br />Where operator has the same meaning of “scale” in OpenFOAM<br />Where<br />Suppose is orthotropic and is the principal material axes<br />Where xyz global coordinate system, <br /> is coordinate transformation tensor.<br />5/22/2009<br />10<br /><br />
  25. 25. GAO-YONG TURBULENCE EUQTIONS<br />energy dissipation due to eddy viscosity is the work done by fluctuation force over L<br />also<br />considering the phenomenon of turbulence energy inversion, <br />item should be subtracted from the right-hand side<br /> of the second equation , therefore<br />5/22/2009<br />11<br /><br />
  26. 26. IMPLEMENTATION<br /><ul><li>Development from scratch
  27. 27. Bad generality, readability
  28. 28. Repeated work
  29. 29. one year for one example
  30. 30. Based on secondary development of closed source software.
  31. 31. Limited the innovation, procedure has to be changed.
  32. 32. Debug is difficult.
  33. 33. Failed
  34. 34. Based on OpenFOAM
  35. 35. Rapidly development
  36. 36. Quick investigation, one month for one example</li></ul>5/22/2009<br />12<br /><br />
  37. 37. NUMERICAL EXAMPLES<br /><ul><li>Lid-driven cavity flow is selected </li></ul> because of simple and the data at hand<br /><ul><li>Reynolds number =10,000
  38. 38. 80X80X1 Grid is employed
  39. 39. Gao-Yong model and K-Epsilon model is seperately used
  40. 40. Transient simulation is finished
  41. 41. Initial flow field is stationary</li></ul>5/22/2009<br />13<br /><br />
  42. 42. Comparison of U-velocity profiles along a vertical line passing through the geometry centre of the cavity<br />5/22/2009<br />14<br /><br />
  43. 43. U-velocity profiles along a vertical line passing through the geometry centre of the cavity from t=0s to t=6s, Gao-Yong turbulence model<br />5/22/2009<br />15<br /><br />
  44. 44. U-velocity profiles along a vertical line passing through the geometry centre of the cavity from t=7s to t=80s, Gao-Yong turbulence model<br />5/22/2009<br />16<br /><br />
  45. 45. Re=10,000<br />Grid 80X80X1, t=80s, Gao-Yong model<br />by Erturk<br />Comparison of Streamlines<br />5/22/2009<br />17<br /><br />
  46. 46. Comparison of Streamlines<br />Re=10,000<br />Grid 80X80X1, t=80s, K-Epsilon model<br />by Erturk<br />5/22/2009<br />18<br /><br />
  47. 47. Streamlines from t=0s to t=6s, Gao-Yong model<br />5/22/2009<br />19<br /><br />
  48. 48. Streamlines from t=7s to t=80s, Gao-Yong model<br />5/22/2009<br />20<br /><br />
  49. 49. Streamlines t=6s, DNS & Gao-Yong model<br />5/22/2009<br />21<br /><br />
  50. 50. The Stream Function Vorticity Method by Erturk<br />Gao-Yong turbulence model t=80s<br />Comparison of Vorticity Contour<br />5/22/2009<br />22<br /><br />Re=10,000 Grid 80X80X1, t=80s<br />
  51. 51. Comparison of Vorticity Contour<br />The Stream Function Vorticity Method by Erturk<br />K-Epsilon Turbulence model t=80s<br />5/22/2009<br />23<br /><br />Re=10,000 Grid 80X80X1, t=80s<br />
  52. 52. Conclusion<br /><ul><li>An innovative CFD method Gao-Yong turbulence model is able to be investigated quickly thanks to the open source software OpenFOAM
  53. 53. Gao-Yong turbulence model is able to gain real viscosity field in complex flow under coarse grid and unsteady condition.
  54. 54. The existing closed source software has limitations to the users, and therefore fail in the research, especially in the innovation research.
  55. 55. There is an improvement space for OpenFOAM in some aspects, such as:
  56. 56. Function of open community.
  57. 57. Open project management.
  58. 58. Open source code management.
  59. 59. Effective bug track system.
  60. 60. User interface.</li></ul>5/22/2009<br />24<br /><br />