3D steady state heat transfer
free form

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Free form approach

SOLIDO offers a more correct simulation compared to an approximation with rectangular blocks (as in TRISCO).

  • Conduction: better correspondence to material quantity and shape.
    Rounded forms approximated by rectangular blocks introduce (incorrect) 3D effects at inner and outer block corners.
  • Convection: the areas of contact surfaces are magnified (up to circa 40 %) by transition to rectangular blocks.  This error is not reduced by grid refinement.
  • Radiation: view factors are determined by surface orientations.
    Rectangular blocks have only orthogonal surface orientations (along coordinate axes).  Grid refinement does not resolve the problem.

Solid modeller
  • An object is modelled in SOLIDO with blocks, using the same superposition rule as in TRISCO.
  • A SOLIDO block is a generalised TRISCO block, in which the eight vertices can get free independent positions.  This allows new shapes (e.g. some with coincident vertices): prism, pyramid, parallelepiped and other.
  • The corners around vertices can be rounded to form solids with quadratic surfaces: sphere, cylinder, cone, hypar shell and other.


CAD input
  • SOLIDO blocks can also refer to STL files as exported from CAD systems (e.g. AutoCAD).
  • STL (Stereolithography Tessellation Language) is the standard data format used in rapid prototypingSTL is a "watertight" model of a (complex) 3D body, containing a triangulation of the body surface.
  • The point coordinates of a STL file can be transformed in SOLIDO to adjust the position of the STL block in the global scene.
  Thermal properties
  • Linked to colours of blocks.
  • Material properties with extensive material database.
  • Boundary conditions at material surfaces, material interfaces, inside materials (volumetric heat source).
  • Improved simulation of separated radiation (using view factors) and convection (function of difference between local surface temperature and air temperature) by use of RADCON module.
  • Automatic calculation of thermal properties for air cavities in accordance with international standards.

Mesh generation
  • SOLIDO uses a rectangular mesh with node fitting to the true object geometry.
  • The user defines a 3D rectangular grid (comparable to grid in TRISCO).
    The grid can be equidistant based on a given resolution and then be optimised to minimise the number of nodes.
  • The object is rasterised in relation to the calculation grid to obtain a rectangular approximation (see left picture).
  • The node coordinates at the outside surfaces or in the interfaces between different colour regions are fitted unto the original object surfaces, to achieve a close match to the original geometry.

input geometry

rasterised object

after node fitting

  • The system of equations is formulated to have the same favourable characteristics as in TRISCO (sparse positive definite linear system).  By this the solution is as fast and stable as in TRISCO.
  • The method is validated against analytical solutions and is far better than the rectangular approximation.
  • 512 Mb RAM can solve about 1 million nodes.
    2 Gb RAM can solve about 6 million nodes.
Graphic output
  • High resolution output
    All graphic output can be saved and printed in any user defined bitmap size.
  • Object clipping
    The object can be clipped at any grid plane to achieve a cross section or a perspective view of an object cutout.  Also materials of given colours can be clipped away.
  • SOLIDO is designed as major product enhancement of TRISCO.
    See upgrade info.
  • SOLIDO can read BISCO data.
  Demo program
  • Download Physibel demo programs and manuals (14 Mb).