有奖问题求解！

benz250 · 发表于 2005-11-10 09:50:01

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我用gambit 划分网格，顺利导入fluent。但是在求解的时候出现了问题！
还没有进行第一步跌代计算求解器就说： solution is converged.
并且从残差图也没有跳出来，我看残差都是0!难怪没有开始跌代！
这到底是怎么回事啊？
为了表示我的感谢。我将给帮我解答的大侠50流体币。谢谢了！

lcw · 发表于 2005-11-10 09:55:54

你把残差值设置成0.00001试试.

lkqhvac · 发表于 2005-11-10 09:58:51

流场初始化时不要全部速度为零，我以前做自然对流时曾遇到相似的问题。

benz250 · 发表于 2005-11-10 11:13:30

我已经设到0.000001了，并且初始流场也不都是零了。还是不行!
虽然没有解答，我也给你们每人25。怎么给呢？
另外，还希望有大侠能帮我看看啊。谢谢了！着急！

trampler · 发表于 2005-11-10 16:20:33

你的初始条件以及边界条件已经与真解一致了，其实不是你想要求的解。
比如：一个长方体内，你想算流体流动，但你把四面都设成绝热壁面，接着
你初始化解时用同样的压力初值，速度为0，以及不考虑重力，那绝对会出现
你上面的情况。
可能你的边界条件有问题

benz250 · 发表于 2005-11-10 17:20:22

大侠能具体说说吗？我是设定最简单的边界条件。速度入口，压力出口，
壁面，interior，没有了！真不知道哪里有问题了。还是谢谢你了！
请问怎么转银子啊？？

trampler · 发表于 2005-11-10 17:30:07

你把你的文件传上来.cas,.dat我看看

benz250 · 发表于 2005-11-10 17:39:52

请问大侠有信箱吗？

benz250 · 发表于 2005-11-10 18:48:47

我以前计算过类似的问题，操作上也不是新手，但是这种情况的确是第一次遇到！
好费解。先形容一下我的流场，其实非常简单，流场为一个长方体实体，流体是空气，沿速度入口以0.05m/s速度流入，压力出口流出，出口面中心的表压为0。四壁皆为壁面。中间有一些缠绕的管道，从长方体实体中减去。（即管道中的空间不在流场内）另外这些管道附近有两个内部表面。平行于入口面。不知怎么回事？我msn: benz5681@hotmail.com QQ: 18046967
step 1 :读入网格：似乎没有问题。
Reading "C:\Documents and Settings\user1\triplelayertop2025TEnoboundary.msh"...
93603 nodes.
24090 mixed wall faces, zone  3.
15908 mixed wall faces, zone  4.
2452 mixed interior faces, zone  5.
2614 mixed interior faces, zone  6.
   224 mixed pressure-outlet faces, zone  7.
   224 mixed velocity-inlet faces, zone  8.
  976247 mixed interior faces, zone 10.
  500768 tetrahedral cells, zone  2.
Building...
   grid,
   materials,
   interface,
   domains,
   zones,
default-interior
inlet
outlet
internalupper
internallower
yarns
wall
fluid
   shell conduction zones,
Done.

Step 2  swap and switch 交换网格使之均匀：不知道这步有没有问题？？
moved 38 nodes, unable to move 0 nodes, most skewness improvement 0.427814, 3 remaining iterations.
moved 39 nodes, unable to move 1 nodes, most skewness improvement 0.156168, 2 remaining iterations.
moved 40 nodes, unable to move 2 nodes, most skewness improvement 0.216834, 1 remaining iterations.
moved 43 nodes, unable to move 3 nodes, most skewness improvement 0.155703, 0 remaining iterations.
Done.
Number faces swapped: 47
Number faces visited: 4128
Number faces swapped: 0
Number faces visited: 4053

step 3  检查网格，似乎也没有问题
Grid Check
Domain Extents:
x-coordinate: min (m) = -3.500000e-004, max (m) = 3.500000e-004
y-coordinate: min (m) = -3.912500e-003, max (m) = 2.762500e-003
z-coordinate: min (m) = -3.500000e-004, max (m) = 3.500000e-004
Volume statistics:
minimum volume (m3): 2.427489e-018
maximum volume (m3): 9.535172e-014
   total volume (m3): 3.223038e-009
Face area statistics:
minimum face area (m2): 2.258267e-012
maximum face area (m2): 4.841403e-009
Checking number of nodes per cell.
Checking number of faces per cell.
Checking thread pointers.
Checking number of cells per face.
Checking face cells.
Checking bridge faces.
Checking right-handed cells.
Checking face handedness.
Checking element type consistency.
Checking boundary types:
Checking face pairs.
Checking periodic boundaries.
Checking node count.
Checking nosolve cell count.
Checking nosolve face count.
Checking face children.
Checking cell children.
Checking storage.
Done.

step 4进行各种设置总结如下：
FLUENT
Version: 3d, segregated, lam (3d, segregated, laminar)
Release: 6.2.16
Title:
Models
------
Model                      Settings
-------------------------------------
Space                      3D
Time                      Steady
Viscous                   Laminar
Heat Transfer             Disabled
Solidification and Melting Disabled
Species Transport          Disabled
Coupled Dispersed Phase    Disabled
Pollutants                Disabled
Soot                      Disabled
Boundary Conditions
-------------------
Zones
   name             id type
   ---------------------------------------
   fluid             2 fluid
   wall             3 wall
   yarns             4 wall
   internallower    5 interior
   internalupper    6 interior
   outlet          7 pressure-outlet
   inlet             8 velocity-inlet
   default-interior 10 interior
Boundary Conditions
   fluid
      Condition                                     Value




-----------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------
---------------------
      Material Name                               air



      Specify source terms?                         no



      Source Terms                                  ((mass (inactive . #f) (constant . 0) (profile  )) (x-momentum
(inactive . #f) (constant . 0) (profile  )) (y-momentum (inactive . #f) (constant . 0) (profile  )) (z-momentum (inactive .
#f) (const
nt . 0) (profile  )))
      Specify fixed values?                         no



      Local Coordinate System for Fixed Velocities no



      Fixed Values                                  ((x-velocity (inactive . #f) (constant . 0) (profile  )) (y-velocity
(inactive . #f) (constant . 0) (profile  )) (z-velocity (inactive . #f) (constant . 0) (profile  )))


      Motion Type                                  0



      X-Velocity Of Zone                            0



      Y-Velocity Of Zone                            0



      Z-Velocity Of Zone                            0



      Rotation speed                               0



      X-Origin of Rotation-Axis                   0



      Y-Origin of Rotation-Axis                   0



      Z-Origin of Rotation-Axis                   0



      X-Component of Rotation-Axis                0



      Y-Component of Rotation-Axis                0



      Z-Component of Rotation-Axis                1



      Deactivated Thread                            no



      Porous zone?                                  no



      Conical porous zone?                         no



      X-Component of Direction-1 Vector             1



      Y-Component of Direction-1 Vector             0



      Z-Component of Direction-1 Vector             0



      X-Component of Direction-2 Vector             0



      Y-Component of Direction-2 Vector             1



      Z-Component of Direction-2 Vector             0



      X-Coordinate of Point on Cone Axis          1



      Y-Coordinate of Point on Cone Axis          0



      Z-Coordinate of Point on Cone Axis          0



      Half Angle of Cone Relative to its Axis       0



      Direction-1 Viscous Resistance                0



      Direction-2 Viscous Resistance                0



      Direction-3 Viscous Resistance                0



      Direction-1 Inertial Resistance             0



      Direction-2 Inertial Resistance             0



      Direction-3 Inertial Resistance             0



      C0 Coefficient for Power-Law                0



      C1 Coefficient for Power-Law                0



      Porosity                                     1



   wall
      Condition                                           Value
      ----------------------------------------------------------
      Enable shell conduction?                            no
      Wall Motion                                        0
      Shear Boundary Condition                            0
      Define wall motion relative to adjacent cell zone? yes
      Apply a rotational velocity to this wall?          no
      Velocity Magnitude                                  0
      X-Component of Wall Translation                   1
      Y-Component of Wall Translation                   0
      Z-Component of Wall Translation                   0
      Define wall velocity components?                   no
      X-Component of Wall Translation                   0
      Y-Component of Wall Translation                   0
      Z-Component of Wall Translation                   0
      Rotation Speed                                     0
      X-Position of Rotation-Axis Origin                0
      Y-Position of Rotation-Axis Origin                0
      Z-Position of Rotation-Axis Origin                0
      X-Component of Rotation-Axis Direction             0
      Y-Component of Rotation-Axis Direction             0
      Z-Component of Rotation-Axis Direction             1
      X-component of shear stress                         0
      Y-component of shear stress                         0
      Z-component of shear stress                         0
      Specularity Coefficient                            0
   yarns
      Condition                                           Value
      ----------------------------------------------------------
      Enable shell conduction?                            no
      Wall Motion                                        0
      Shear Boundary Condition                            0
      Define wall motion relative to adjacent cell zone? yes
      Apply a rotational velocity to this wall?          no
      Velocity Magnitude                                  0
      X-Component of Wall Translation                   1
      Y-Component of Wall Translation                   0
      Z-Component of Wall Translation                   0
      Define wall velocity components?                   no
      X-Component of Wall Translation                   0
      Y-Component of Wall Translation                   0
      Z-Component of Wall Translation                   0
      Rotation Speed                                     0
      X-Position of Rotation-Axis Origin                0
      Y-Position of Rotation-Axis Origin                0
      Z-Position of Rotation-Axis Origin                0
      X-Component of Rotation-Axis Direction             0
      Y-Component of Rotation-Axis Direction             0
      Z-Component of Rotation-Axis Direction             1
      X-component of shear stress                         0
      Y-component of shear stress                         0
      Z-component of shear stress                         0
      Specularity Coefficient                            0
   internallower
      Condition Value
      -----------------
   internalupper
      Condition Value
      -----------------
   outlet
      Condition                               Value
      ------------------------------------------------
      Gauge Pressure                            0
      Radial Equilibrium Pressure Distribution no
      Backflow Direction Specification Method 1
      Coordinate System                         0
      X-Component of Flow Direction             1
      Y-Component of Flow Direction             0
      Z-Component of Flow Direction             0
      X-Component of Axis Direction             1
      Y-Component of Axis Direction             0
      Z-Component of Axis Direction             0
      X-Coordinate of Axis Origin             0
      Y-Coordinate of Axis Origin             0
      Z-Coordinate of Axis Origin             0
      is zone used in mixing-plane model?       no
      Specify targeted mass-flow rate          no
      Targeted mass-flow                      1
   inlet
      Condition                            Value
      -------------------------------------------------
      Velocity Specification Method       2
      Reference Frame                      0
      Velocity Magnitude                   0.050000001
      Coordinate System                   0
      X-Velocity                         0
      Y-Velocity                         0
      Z-Velocity                         0
      X-Component of Flow Direction       1
      Y-Component of Flow Direction       0
      Z-Component of Flow Direction       0
      X-Component of Axis Direction       1
      Y-Component of Axis Direction       0
      Z-Component of Axis Direction       0
      X-Coordinate of Axis Origin          0
      Y-Coordinate of Axis Origin          0
      Z-Coordinate of Axis Origin          0
      Angular velocity                   0
      is zone used in mixing-plane model? no
   default-interior
      Condition Value
      -----------------
Solver Controls
---------------
Equations
   Equation Solved
   -----------------
   Flow    yes
Numerics
   Numeric                      Enabled
   ---------------------------------------
   Absolute Velocity Formulation yes
Relaxation
   Variable    Relaxation Factor
   -------------------------------
   Pressure    1
   Density    1
   Body Forces 1
   Momentum    0.80000001
Linear Solver
               Solver    Termination Residual Reduction
   Variable    Type    Criterion    Tolerance
   --------------------------------------------------------
   Pressure    V-Cycle 0.1
   X-Momentum Flexible 0.1          0.7
   Y-Momentum Flexible 0.1          0.7
   Z-Momentum Flexible 0.1          0.7
Discretization Scheme
   Variable Scheme
   ------------------------------
   Pressure Second Order
   Momentum Second Order Upwind
Solution Limits
   Quantity                   Limit
   ---------------------------------
   Minimum Absolute Pressure 1
   Maximum Absolute Pressure 5e+10
   Minimum Temperature       1
   Maximum Temperature       5000
Material Properties
-------------------
Material: air (fluid)
   Property                      Units    Method    Value(s)
   ----------------------------------------------------------------
   Density                      kg/m3    constant 1.225
   Cp (Specific Heat)             j/kg-k    constant 1006.43
   Thermal Conductivity          w/m-k    constant 0.0242
   Viscosity                      kg/m-s    constant 1.7894e-05
   Molecular Weight             kg/kgmol constant 28.966
   L-J Characteristic Length    angstrom constant 3.711
   L-J Energy Parameter          k       constant 78.6
   Thermal Expansion Coefficient 1/k       constant 0
   Degrees of Freedom                      constant 0
   Speed of Sound                m/s       none    #f
Material: aluminum (solid)
   Property             Units Method    Value(s)
   ---------------------------------------------------
   Density             kg/m3 constant 2719
   Cp (Specific Heat)    j/kg-k constant 871
   Thermal Conductivity w/m-k constant 202.4

step5 最后跌代，这次好像可以计算了，但是不知为什么残差曲线窗口还是没有弹出来？我明确设置残差图要plot了！奇怪。
我监视的入口处质量流量图成锯齿状！每个跌代步都要震动一下，即先跳到一个值，然后陡然回到近似于0的位置。这个值随着跌代而减小。好奇怪！
我进行了将近1000次跌代，都是如此。这里只列出小部分数据。
iter continuity x-velocity y-velocity z-velocity    time/iter
reversed flow in 224 faces on pressure-outlet 7.
   1 1.0000e+00 2.7929e-03 2.9984e-02 2.8342e-03  1:39:54  999
reversed flow in 201 faces on pressure-outlet 7.
   2 1.0000e+00 3.4982e-01 7.2242e-01 1.7641e-01  1:36:28  998
   3 7.1765e-01 5.5250e-02 2.2280e-01 2.7672e-02  1:37:02  997
   4 5.1346e-01 6.5614e-02 1.2150e-01 4.9258e-02  1:34:09  996
   5 3.3444e-01 4.3119e-02 6.0991e-02 3.9887e-02  1:35:09  995
   6 2.8882e-01 2.7505e-02 3.7272e-02 2.7949e-02  1:35:55  994
   7 2.1143e-01 7.8588e-03 1.3192e-02 7.9927e-03  1:33:13  993
   8 1.5038e-01 4.4134e-03 7.7544e-03 4.4925e-03  1:31:02  992
   9 1.1568e-01 3.1227e-03 6.4318e-03 3.1600e-03  1:32:34  991
10 9.0543e-02 2.3968e-03 5.5531e-03 2.4185e-03  1:30:29  990
11 7.2225e-02 1.9715e-03 5.0136e-03 1.9823e-03  1:32:05  989
  iter continuity x-velocity y-velocity z-velocity    time/iter
12 5.8263e-02 1.6475e-03 4.5876e-03 1.6501e-03  1:30:04  988
13 4.7306e-02 1.5450e-03 4.3575e-03 1.5463e-03  1:31:43  987
14 3.8673e-02 1.2400e-03 3.9790e-03 1.2355e-03  1:33:01  986
15 3.2244e-02 1.1642e-03 3.6967e-03 1.1493e-03  1:34:02  985
16 2.6811e-02 1.0363e-03 3.4217e-03 1.0446e-03  1:34:50  984
Interrupting...
Done.

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有奖问题求解！

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