Description: A progressive viewfactor integration scheme has been introduced that provides more accurate results in cavity radiation analyses. The new scheme identifies regions where different levels of approximations can be used to provide the right balance of efficiency and accuracy: when facets are sufficiently far from each other, a fast lumped area approximation is used. If the facets are close to each other, but one of the facets is much larger than the other, an infinitesimal-to-finite approximation is used. For all other cases a contour integral is calculated numerically using the integration points on each edge to compute the viewfactor.

The lumped area approximation was the only available method of viewfactor calculation in previous releases. To revert back to the old radiation viewfactor behavior, set both the Lumped area distance-square value and Infinitesimal facet area ratio parameters to zero.

Figure 11–8 shows the the default viewfactor selections for a cavity radiation interaction in the Abaqus/CAE Edit Interaction dialog box.

Interaction module:
    InteractionCreate: Cavity radiation: Viewfactors: Infinitesimal facet area ratio, 
    Gauss integration points per edge, and Lumped area distance-square value, 
    or Defaults to reset the default values for all viewfactor parameters