New adaptation

There are many improvements in new version of FlowVision 31001. They significantly concern to functionality of adjusting and editing of computational grid such as computational grid adaptation, parameters of boundary layer grid etc. The list of main changes in comparison with FlowVision 31001:

  • All adaptations and boundary layer grid are specified now in separate section of project tree named “computational grid”
  • In project tree active adaptations and boundary layer grid are highlighted by color while inactive adaptations are grey-colored
  • Subregions and geometrical objects in PreProcessor with the same settings of computational grid can be grouped to single subsection of project tree. It is not necessary to repeat this settings separately for each item anymore.
  • It is possible to adjust number of layers for intermediate adaptation levels (not only for maximal adaptation level as in previous version). It is not necessary to create such grid during several number of solution steps
  • New function is “adaptation by condition” which allow to make split of cells according to specified condition (range of values for variables)

These and other most meaningful features are described below.

What cells can be called Small cells

In FlowVision uses Cartesian grid that can be automatically locally downscaled. Grid cells intersecting computational domain boundaries and computational subregions are clipped by boundary surfaces.

fig1 cutcell

Fig.1. Splitting cells by geometry surface

After such clipping it is possible that size of new cells will be in many times smaller than initial cell:

fig2 smallcells

Fig. 2. Small cells

When the radiation model can be used?

If the radiation heat flow is comparable with other heat flow, which is the main heat flow source in the problem (for example, convective heat flow), you have to use a radiation model.

The radiation heat flow can be evaluated based on temperature difference between surrounding environment and the body’s surface using the Stefan-Boltzmann's law:

rad eq 11

The formula above represents the low for the absolutely black body (Plankian radiator). For real bodies you have to multiply the value by emissivity factor.

rad eq 22

At present, usage of PrePostprocessor (PPP) is officially supported only for Windows. However, sometimes it is necessary to run PPP on Linux too. Customers of FlowVision have the ability to do so due to special software, like Wine, that allows running windows applications on Linux. Let us demonstrate how to run PPP on Linux using Wine-5.0 on Ubuntu 20.04.2, to show you just how easy it is. The software version used in this article is FlowVision 3.12.02.