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14  GROUP RM—CHANGE OF TOPOLOGY
("REMAILLAGE")

RM.10


Object:


This directive enables “remeshing”, i.e. changing the topology of a part of the mesh previously defined by directive "GEOM".


Note that this is very different from mesh “rezoning”, i.e. prescribing the motion of a fluid grid in ALE computations. In fact, rezoning operations just move the nodes, without changing the topology (number of nodes and elements, composition of the elements).


For remeshing, two options are possible:


With the option "AUTOMATIQUE", the user has to supply only the boundary points of the zone submitted to remeshing, then EUROPLEXUS builds a new and more regular mesh based on the boundary.


With the option "MANUEL", the user must enumerate all the elements which are to be eliminated and supply the new mesh.


At the present time, only 3-noded triangles ("TRIA") can be taken into account.


Syntax:
     "REMAILLAGE"
          $   "AUTOMATIQUE"   . . .   $
          $   "MANUEL"        . . .   $



Comments:


The suppressed elements must belong to the same zone (defined by the instruction "GEOMETRIE").

14.1  AUTOMATIC REMESHING

RM.20


Object:


The new sub-mesh is created by EUROPLEXUS. Therefore, only the boundary points are necessary. As a matter of fact, these points should be common to the old and the new mesh.


Syntax:

   "AUTOMATIQUE"   "CONTOUR"   /LECTURE/
                   "AJOUTER"   npts*( xi , yi )
                   < "ELEM"  ideb ifin >  < "ZONE"  nzone >
                   < "MAIL"  < nmail > >  < "STOP" >


/LECTURE/

Numbers of the existing points making up the boundary.
npts

Number of points to be added.
xi , yi

Coordinates of the added points (abscissa then ordinate for each of the npts points).
ideb,ifin

The numbers of the elements of the zone concerned are lying between ideb and ifin.
nzone

The elements of the zone to be remeshed belong to the zone number nzone.
nmail

Number of the logical unit (by default nmail = 7), where the data set available for the procedure "LECTURE" of "COCO" is stored.

Comments:


If the boundary point is an existing node, it is defined by its number.


If it is an added point, it is defined by a negative number. In this case, at the end to the procedure /LECTURE/, the user must enter the coordinates of these points in the same order as they are mentioned in the procedure, by the means of the instruction "AJOUTER".


The directives "ELEM" and "ZONE" enable the elements submitted for remeshing to be limited.


By means of the directive "MAIL", the user can obtain a data set for "COCO" in order to plot the results of the remeshing.


The key-word "STOP" stops EUROPLEXUS when the mesh is created and enables the user to check his mesh.

14.2  MANUAL REMESHING

RM.30


Object:


This option enables a new partial mesh to be explicitly entered.


Syntax :

   "MANUEL"   izone   nelim   nelaj   npaj
           "ANCIEN"   /LECTURE/
           "NOUVEAU"

             . . .    COCO data set . . .

           "IDENTIFIER"   npts*( numl  numg )


izone

Number of the zone of elements which must be eliminated.
nelim

Total number of the elements to be eliminated.
nelaj

Total number of the elements to be added and belonging to the new sub-mesh.
npaj

Total number of points belonging to the new sub-mesh.
ANCIEN

Keyword defining the old sub-mesh.
LECTURE

List of the elements belonging to the sub-mesh to be eliminated.
NOUVEAU

Keyword introducing the "COCO" data set of the new sub-mesh.
npts

Number of pairs (local number, global number) to be identified.
numl

Local number of the node in the sub-mesh
numg

Number of that same node in the global mesh.

Comments:


The "COCO" data set with its title is composed of the coordinates of the new sub-mesh (in format 6E12.5) and of the numbers of the mesh elements (in format 18I4).


The key-word "IDENTIFIER" enables the integration of the new sub-mesh into the global mesh to be defined.

14.3  CHECKING THE REMESHING

RM.40


Object:


To edit (verify) the result of a remeshing operation.


Syntax:

   < "PERFO" nuperf >  < "TRACE" nutrac >  < "SAUVE" nusauv >



During a restart the user can save data for another restart.

nuperf

Number of the logical unit which will contain the "COCO" data necessary to plot a new sub-mesh.
nutrac

Necessary to write the results on the file "TRACE" number nutrac.
nusauv

To save the results on the file nusauv, so as to enable a further restart.

Comments:


The user is advised to use these commands, because the numbers of certain elements may have changed after a remeshing. That is why it is necessary to save that time step ( considered by EUROPLEXUS as step zero). Do not forget to check that the new mesh is correct before the computation continues by means of a restart ("REPRISE").


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