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Feb 21st, 2018
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  1. lc = 0.03;
  2. rc = 0.01;
  3. xp = 0.01;
  4. c = 0.005;
  5. rp = rc - c;
  6. lp = lc - xp;
  7. Subscript[T, 0] = 300;
  8. Subscript[[Eta], 0] = 1.846*10^-5;
  9. Subscript[P, 1] = 6*10^5 ;
  10. Subscript[P, 0] = 10^5;
  11. Subscript[c, P] = 1004.9;
  12. Subscript[c, [Nu]] = 717.8;
  13. Subscript[R, 0] = Subscript[c, P] - Subscript[c, [Nu]];
  14. [CapitalOmega] = RegionDifference[
  15. Rectangle[{0, 0}, {lc, rc}],
  16. Rectangle[{xp, 0}, {xp + lp, rp}]];
  17.  
  18. Needs["NDSolve`FEM`"];
  19. mesh = ToElementMesh[[CapitalOmega],
  20. "MaxBoundaryCellMeasure" -> 0.00001,
  21. MaxCellMeasure -> {"Length" -> 0.0008},
  22. "MeshElementConstraint" -> 20, MeshQualityGoal -> "Maximal"][
  23. "Wireframe"]
  24.  
  25. eqn1 = D[[Rho][x, r]*Subscript[[Nu], x][x, r], x] +
  26. D[r*[Rho][x, r]*Subscript[[Nu], r][x, r], r]/r == 0 ;
  27. eqn2 = D[[Rho][x, r]*Subscript[[Nu], x][x, r]^2 +
  28. Subscript[R, 0] [Rho][x, r]*T[x, r], x] +
  29. D[r*([Rho][x, r]*Subscript[[Nu], x][x, r]*
  30. Subscript[[Nu], r][x, r] +
  31. Subscript[[Eta], 0]*D[Subscript[[Nu], x][x, r], r]), r]/
  32. r == 0 ;
  33. eqn3 = D[[Rho][x, r]*Subscript[[Nu], x][x, r]*
  34. Subscript[[Nu], r][x, r] +
  35. Subscript[[Eta], 0]*D[Subscript[[Nu], r][x, r], x], x] +
  36. D[r*([Rho][x, r]*Subscript[[Nu], r][x, r]^2 +
  37. Subscript[R, 0] [Rho][x, r]*T[x, r]), r]/r == 0;
  38. eqn4 = Subscript[
  39. c, [Nu]]*[Rho][x,
  40. r]*(Subscript[[Nu], x][x, r]*D[T[x, r], x] +
  41. Subscript[[Nu], r][x, r]*D[T[x, r], r]) +
  42. Subscript[R, 0]*[Rho][x, r]*
  43. T[x, r]*(D[Subscript[[Nu], x][x, r], x] +
  44. D[r*Subscript[[Nu], r][x, r], x]/r) + (2*
  45. D[Subscript[[Nu], x][x, r], x]^2 +
  46. 2*D[Subscript[[Nu], r][x, r],
  47. r]^2 + (D[Subscript[[Nu], x][x, r], r] +
  48.  
  49. D[Subscript[[Nu], r][x, r],
  50. x])^2 - ((D[Subscript[[Nu], x][x, r], x] +
  51. D[r*Subscript[[Nu], r][x, r], x]/r)^2)*2/3)*
  52. Subscript[[Eta], 0] == 0;
  53.  
  54. bc1 = Subscript[R, 0] [Rho][0, r]*Subscript[T, 0] == Subscript[P, 1]
  55. bc2 = Subscript[R, 0] [Rho][lc, r]*Subscript[T, 0] == Subscript[P, 0]
  56. bc3 = DirichletCondition[{Subscript[[Nu], r][x, 0] == 0,
  57. D[Subscript[[Nu], r][x, r], r] == 0,
  58. D[Subscript[[Nu], x][x, r], r] == 0, D[[Rho][x, r], r] == 0,
  59. D[T[x, r], r] == 0}, r == 0 && (0 <= x <= xp )]
  60. bc4 = DirichletCondition[{Subscript[[Nu], r][x, r] == 0,
  61. Subscript[[Nu], x][x, r] ==
  62. 0}, (0 <= r <= rp && x == xp ) || (r == rp &&
  63. xp <= x <= xp + lp) || (r == rc && 0 <= x <= lc) ] == 0
  64. bcs = {bc1, bc2, bc3, bc4};
  65.  
  66. {[Nu]xsol, [Nu]rsol, Tsol, [Rho]sol} =
  67. NDSolveValue[{eqns, , bcs}, {Subscript[[Nu], x], Subscript[[Nu],
  68. r], [Rho], T}, {x, r} [Element] mesh,
  69. Method -> {"FiniteElement",
  70. "InterpolationOrder" -> {Subscript[[Nu], x] -> 2,
  71. Subscript[[Nu], r] -> 2, [Rho] -> 1, T -> 1},
  72. "IntegrationOrder" -> 5}];
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