10/17/2006 Cylinder In Cross Flow


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In this computational run, I designed a small duct with a cylinder inside of it. This geometry was meshed using Ansys Workbench, pre-processed using CFX, and post-processed using CFX. It was solved using CFX with a LES Turbulence Model turbulence model and was run on one core.

The job took nearly 24 hours to solve and resulted in around 8 sec of simulation-time data.

The length of time this model took to run has made me realize CFX will not be an acceptbale solution to modeling the entire Flume. Even with the help of John Harris in the ECE dept and the use of his cluster (allowing illegal ansys), the solution to an LES problem of that scale will take too long to solve. I would need more computing power, and the only other option is to run CFD code on something like System X. If I do this though, I will need to make sure I run legal software. So I cant use CFX.

At this point, I have found another CFD code that might work well. It is called Open_Foam, an open source, GPL, project. It includes many DNS and LES solvers



Post-Processing Results


Velocity Vectors of Sheading
EnlargeVelocity Vectors of Sheading



image VRML file of velocity vectors at 0.3sec

image VRML file of velocity vectors at 4.3sec

image VRML file of wall pressure at 0.3sec

image Movie of the 8sec run



Job Statistics


 +--------------------------------------------------------------------+
 |                          Job Information                           |
 +--------------------------------------------------------------------+

 Run mode:       serial run

 Host computer:  RCO-BEAST
 Job started:    Mon Oct 16 23:13:11 2006


 +--------------------------------------------------------------------+
 |        Memory Allocated for Run  (Actual usage may be less)        |
 +--------------------------------------------------------------------+

  Data Type      Kwords  Words/Node  Words/Elem     Kbytes  Bytes/Node
 
  Real           4863.0      740.86      140.96    18996.1     2963.44
  Integer        1573.5      239.71       45.61     6146.3      958.84
  Character      2323.4      353.96       67.35     2269.0      353.96
  Logical          40.0        6.09        1.16      156.2       24.38
  Double          215.0       32.75        6.23     1679.6      262.03


 +--------------------------------------------------------------------+
 |             Total Number of Nodes, Elements, and Faces             |
 +--------------------------------------------------------------------+

 Domain Name : Pipe

     Total Number of Nodes                                =        6564

     Total Number of Elements                             =       34499
         Total Number of Tetrahedrons                     =       34499

     Total Number of Faces                                =        2630


 +--------------------------------------------------------------------+
 |                     Average Scale Information                      |
 +--------------------------------------------------------------------+

 Domain Name : Pipe
     Global Length                                         = 1.4885E-01
     Minimum Extent                                        = 8.2000E-02
     Maximum Extent                                        = 3.0000E-01
     Density                                               = 9.9700E+02
     Dynamic Viscosity                                     = 8.8990E-04
     Velocity                                              = 1.0000E-01
     Advection Time                                        = 1.4885E+00
     RMS Courant Number                                    = 3.2269E-02
     Maximum Courant Number                                = 1.0529E-01
     Reynolds Number                                       = 1.6676E+04


[run]

 +--------------------------------------------------------------------+
 |                     Average Scale Information                      |
 +--------------------------------------------------------------------+

 Domain Name : Pipe
     Global Length                                         = 1.4885E-01
     Minimum Extent                                        = 8.2000E-02
     Maximum Extent                                        = 3.0000E-01
     Density                                               = 9.9700E+02
     Dynamic Viscosity                                     = 8.8990E-04
     Velocity                                              = 3.3797E+00
     Advection Time                                        = 4.4042E-02
     RMS Courant Number                                    = 9.4047E-01
     Maximum Courant Number                                = 3.0608E+00
     Reynolds Number                                       = 5.6361E+05
     
     
 +--------------------------------------------------------------------+
 |               CPU Requirements of Numerical Solution               |
 +--------------------------------------------------------------------+

 Subsystem Name                  Discretization       Linear Solution
                                (secs.   %total)     (secs.   %total) 
 ----------------------------------------------------------------------
 Wall Scale                     1.16E+00   0.0 %     7.19E-01   0.0 %
 Momentum and Mass              5.52E+04  68.9 %     1.06E+04  13.3 %
                                -------- -------     --------  ------
 Subsystem Summary              5.52E+04  68.9 %     1.06E+04  13.3 %

 Variable Updates               8.67E+03  10.8 %
 Miscellaneous                  5.63E+03   7.0 %
                                --------
 Total                          8.01E+04


 +--------------------------------------------------------------------+
 |                          Job Information                           |
 +--------------------------------------------------------------------+

 Host computer:  RCO-BEAST
 Job finished:   Tue Oct 17 22:54:37 2006
 Total CPU time: 8.013E+04 seconds
             or: (          0:        22:        15:    29.516 )
                 (       Days:     Hours:   Minutes:   Seconds )

 Total wall clock time: 8.529E+04 seconds
             or: (          0:        23:        41:    26.000 )
                 (       Days:     Hours:   Minutes:   Seconds )



Original Files


image NX4 part file

image Parasolid part file

image CFX-Pre file

Events


Friday, February 02, 2007 (10)