Requirement :
The MESH MUST BE CONFORM to obtain CONTINUOUS solutions <=>
The INTERSECTION of 2 FINITE ELEMENTS may be one FACE, one EDGE, one VERTEX or EMPTY, but NOT only a PART of them.

The Mefisto TOP-DOWN ANALYSIS to construct the mesh:
  • The objects may be decomposed in parts with respect to planes or axis of symmetry and parts such that one algorithm of Mefisto can be used on.
  • These parts are volumes and a choice of one algorithm must be done on each. A good knowledge of Mefisto volume algorithms is necessary.
  • For each volume, when one algorithm has been chosen, the input data to execute it must be defined. Generally, these data are a list of surfaces or lines or points which must be meshed.
  • For each surface, a Mefisto algorithm must be chosen and the input data to execute it must be defined. Generally, these data are a list of lines or points.
  • For each line, a Mefisto algorithm must be chosen and the input data to execute it must be defined. Generally, these data are a list of points.
    => a list of Volumes, Surfaces, Lines, Points and the algorithms to construct them.

    The ANALYSIS has been done, on a rough paper, NOT in front of a computer, from Volumes to Surfaces, to Lines, to Points. This is a TOP-DOWN analysis, from the whole complex object to its simplest geometric entities.


    The Mefisto BOTTOM-UP CONSTRUCTION of the mesh:

    The construction is now done in front of a computer by typing commands.
    This way guarantees the conformity, the continuity of the mesh at interfaces which is computed once, but referenced several times.



    A demonstration to construct a mesh of a crank shaft

    The Mefisto-MESHER data file of test/demo: The POINTS
    The Mefisto-MESHER data file of test/demo: The LINES
    The Mefisto-MESHER data file of test/demo: The SURFACES
    The Mefisto-MESHER data file of test/demo: The VOLUMES 1
    The Mefisto-MESHER data file of test/demo: The VOLUMES 2
    The Mefisto-MESHER data file of test/demo: The OBJECT
    The Mefisto-HEATER data file of test/demo: The HEAT PROBLEM
    The Mefisto-ELASTICER data file of test/demo: The ELASTICITY PROBLEM
    The Mefisto-ELASTICER data file of test/demo: The EIGENFREQUENCY PROBLEM



    Remark:
    Mefisto stores the coordinates of the finite element vertices and the vertice number of each finite element.
    But, in fact, if the object has "curved" lines or surfaces and if the mesh algorithm permits it, the tangents of edges of finite elements are also stored to take in account the P3-Hermite curve, the reduced Hsieh-Clough-Tocher triangle and the reduced de Veubeke-Sander quadrangle, in order to construct G1-continuous meshes on surfaces.
    G1 Finite Elements
    P3 HERMITE's segment and triangle
    P3 HERMITE's segment example
    HSIEH CLOUGH TOCHER triangle in 2D
    HSIEH CLOUGH TOCHER triangle in 3D
    HSIEH CLOUGH TOCHER triangle 2D example
    HSIEH CLOUGH TOCHER triangle 3D example 1
    HSIEH CLOUGH TOCHER triangle 3D example 2
    de VEUBEKE SANDER quadrangle in 2D
    de VEUBEKE SANDER quadrangle 2D example 1
    de VEUBEKE SANDER quadrangle 2D example 2
    de VEUBEKE SANDER quadrangle 2D example 3
    de VEUBEKE SANDER quadrangle 3D example 1
    de VEUBEKE SANDER quadrangle 3D example 2



    The Mefisto ALGORITHMS to construct a mesh of an object:
  • MESHER: Option 90; The file xyznsef.plsv.PLSVName:
    This file is created in the mefistox project directory to be used in other softwares.
    The fortran subroutine $MEFISTO/mail/xyzsef.f constructs it.
    This file contains the 3 coordinates of FE vertices and the number of vertices of every FE of a PLSV.

  • MESHER: Option 91; The file xyznpef.ObjectName:
    This file is created in the mefistox project directory to be used in other softwares.
    The fortran subroutine $MEFISTO/mail/xyznpe.f constructs it.
    This file contains the 3 coordinates of FE nodes and the number of nodes of every FE of every FE types of the interpolation of an OBJECT.
    A fortran subroutine $MEFISTO/mail/ReadObjMesh.f recuperates the data.

  • Short manuals: Written in October 2006 by Lung Sheng Chien,
    Department of Mathematics, Tsing Hua University TAIWAN


    Some meshes obtained with Mefisto-Mesher:


    A tetrahedrization of a 3-axis piece


    The rainbow colors show the quality from blue of the best quality 1 to red of the worst quality 0.






    The Mefisto-MESHER data file of test/triax


    A surface mesh of a prototype car














    The rough draft 1 of algorithms of the test/bm
    The rough draft 2 of algorithms of the test/bm
    The Mefisto-MESHER data file of the test/bm

    A surface mesh of a prototype car with the function Taille_Ideale(x,y,z) or Edge_Length(x,y,z)


    The Mefisto-MESHER data file of the test/bm


    A triangulation of the YF22 fighter






















    The rough draft 1 of algorithms of the test/yf
    The rough draft 2 of algorithms of the test/yf
    The points, lines and surfaces of the test/yf
    The Mefisto-MESHER data file of the test/yf


    Return to the Mefisto generality page


    Page written by Alain Perronnet     Last update: October 28-th 2009