Example 21h: Face-fitting in volume elements with collapsed nodes

This example illustrates face-fitting of a volume element which has collapsed nodes (top two nodes). Figure 2 depicts the fitted mesh with single version for the derivatives of the collapsed nodes. The fitted mesh shown in the figure 3 has multiple versions for the derivatives of the collpased nodes. Currently CMISS is capable of face-fitting in volume meshes containing nodes collapsed at any xi location (xi1=0.0, xi1=1.0 ... etc.) and in any xi directions.
Note how the derivatives of the collapsed nodes with multiple versions are fixed in the *.ipfit files and see the note in the com file.

Created by: Kumar Mithraratne Aug. 2002.

The comfile run by this example is as follows:

$name = 'collapse';
$tot_itt=2;
$off=1000;
$offi=100;
$offd=0

fem def para;r;${name};example          # Declares array dimensions 
fem def coord;r;${name};example         # Defines the coordinate system
fem def base;r;${name}_cubic;example    # Reads in nodal information
fem def node;r;${name}_version;example  # Defines tri-cubic Hermite basis funcs.
fem def elem;r;${name}_version;example

fem update nodes derivative 1 linear;   # Updates the derivatives in all three
fem update nodes derivative 2 linear;   # xi directions
fem update nodes derivative 3 linear;   #

fem export node;${name}_initial as ${name}_initial offset $offi;
fem export elem;${name}_initial as ${name}_initial offset_node $offi offset_elem $offi;

fem def field;r;${name}_version;example      # Reads in field variables
fem def elem;r;${name}_version;example field # Defines connectivity of fld. var.
fem update field from geometry               # Updates field 

fem group faces 1,2,3,4,5 as FFFFF           # Defines face group

fem def data;r;${name};example          # Reads in data information

fem def xi;c closest_face search_start 3 faces FFFFF   
# Projects data onto faces, the search_start N option controls the number
# of faces that will be searched to find the closest. The faces to
# be searched are chosen by measuring the distance from the data point
# to a seed point or points on every face then the closest N are used
# to do an orthogonal projection and the closest one of those is
# selected. It is done this way because it is computationally more
# efficient to measure the distance to a point on the face than it is
# to do an orthogonal projection. For this small example problem it's
# not an issue but for larger meshes it could be.
# The number of faces to include in the search can be specfied using the
# search_start option and number of seed points to use (actually the number
# you specify is the square root of the no of seed points)  
# can be specified using the seed_points option. However using too many 
# seed points can be slower than using a large search_start value. It may
# take a bit of trial and error to figure out the best combination. The
# brute force "can't fail" approach is to make the search value equal
# to the number of faces in the problem then the command will attempt
# an orthogonal projection onto every face and will choose the closest.

#fem def xi;w;${name} closest_face faces FFFFF   # only in group FFFFF.
fem li data error;                              # Writes out xi positions

fem export data;${name}_initial_error error as ${name}_initial_error

for ($fit_itt=1; $fit_itt<=$tot_itt; $fit_itt=$fit_itt+1)
  {
   # Note that the node position and Xi1 derivative are fixed in the ipfit
   # file. This means that the collapsed Xi1 line, connecting nodes 5 and 6
   # does not get fitted. If either of these is unfixed then the positions
   # and Xi1 derivatives for each version are not consistent and the mesh
   # has "holes" in it. Fixing none of the fit variables causes cm to crash.
   fem def fit;r;${name}_${fit_itt};example geometry faces FFFFF
   fem fit
   fem update node fit
   fem update scale_factor normalise
   fem def xi;c closest_face search_start 3 faces FFFFF #old

   system "echo ' ======================================================' "    
   fem li data error
   system "echo ' ITERATION ${fit_itt} DONE' "
   system "echo ' ======================================================' "
  }
fem export data;${name}_fitted_error error as ${name}_fitted_error offset $offd 
fem export nodes;${name}_fitted as ${name}_fitted offset $off;
fem export elem;${name}_fitted as ${name}_fitted offset_node $off offset_elem $off;

Additional testing commands:

fem list nodes

Files used by this example are:

Name                       Modified     Size

example_21h.com            09-Apr-2005  3.6k
collapse.exdata            16-Aug-2002   21k
collapse.ipcoor            16-Aug-2002  570 
collapse.ipdata            16-Aug-2002   26k
collapse.ippara            12-Nov-2002  5.9k
collapse.ipxi              16-Aug-2002   33k
collapse_1.ipfit           13-Apr-2007  8.0k
collapse_2.ipfit           13-Apr-2007  8.0k
collapse_cubic.ipbase      16-Aug-2002  4.4k
collapse_fitted.exelem     16-Aug-2002  9.6k
collapse_fitted.exnode     16-Aug-2002   11k
collapse_initial.exelem    16-Aug-2002  6.1k
collapse_initial.exnode    16-Aug-2002  5.7k
collapse_nover_1.ipfit     13-Apr-2007  1.8k
collapse_nover_2.ipfit     13-Apr-2007  1.8k
collapse_noversion.ipelem  16-Aug-2002  404 
collapse_noversion.ipelfd  16-Aug-2002  389 
collapse_noversion.ipfiel  16-Aug-2002   10k
collapse_noversion.ipnode  16-Aug-2002  9.5k
collapse_version.ipelem    16-Aug-2002  1.3k
collapse_version.ipelfd    16-Aug-2002  1.2k
collapse_version.ipfiel    16-Aug-2002   14k
collapse_version.ipnode    16-Aug-2002   13k
test_output.com            16-Aug-2002   15 
viewfit.com                21-Mar-2005  2.6k

Download the entire example:

Name                      Modified     Size

examples_2_21_21h.tar.gz  14-Apr-2007   84k

Testing status by version:

Testing status by file:

• cmiss_test.log
  

  i686-linux
  Success	cm:	cmiss_test.log.retain.
  Success	cm-debug:	cmiss_test.log.retain.
  mips-irix
  Success	cm:	cmiss_test.log.retain.
  Success	cm-debug:	cmiss_test.log.retain.
  Success	cm-debug-clear-malloc:	cmiss_test.log.retain.
  Success	cm-debug-clear-malloc7:	cmiss_test.log.retain.
  Success	cm64:	cmiss_test.log.retain.
  Success	cm64-debug:	cmiss_test.log.retain.
  Success	cm64-debug-clear-malloc:	cmiss_test.log.retain.
  rs6000-aix
  Success	cm:	cmiss_test.log.retain.
  Success	cm-debug:	cmiss_test.log.retain.
  Success	cm64:	cmiss_test.log.retain.
  Success	cm64-debug:	cmiss_test.log.retain.
  x86_64-linux
  Success	cm:	cmiss_test.log.retain.
  Success	cm-debug:	cmiss_test.log.retain.

  
  
• cmiss_test.out
  

  i686-linux
  Success	cm:	ndiff test: no significant differences with generic answer.
  Success	cm-debug:	ndiff test: no significant differences with generic answer.
  mips-irix
  Success	cm:	ndiff test: no significant differences with generic answer.
  Success	cm-debug:	ndiff test: no significant differences with generic answer.
  Success	cm-debug-clear-malloc:	ndiff test: no significant differences with generic answer.
  Success	cm-debug-clear-malloc7:	ndiff test: no significant differences with generic answer.
  Success	cm64:	ndiff test: no significant differences with generic answer.
  Success	cm64-debug:	ndiff test: no significant differences with generic answer.
  Success	cm64-debug-clear-malloc:	ndiff test: no significant differences with generic answer.
  rs6000-aix
  Success	cm:	ndiff test: no significant differences with generic answer.
  Success	cm-debug:	ndiff test: no significant differences with generic answer.
  Success	cm64:	ndiff test: no significant differences with generic answer.
  Success	cm64-debug:	ndiff test: no significant differences with generic answer.
  x86_64-linux
  Success	cm:	ndiff test: no significant differences with generic answer.
  Success	cm-debug:	ndiff test: no significant differences with generic answer.

  
  

Html last generated: Sun Mar 6 05:50:11 2016

Input last modified: Fri Apr 13 10:31:03 2007