Update: January 24, 2018

$FOAM_TUTORIALS/combustion/PDRFoam/flamePropagationWithObstacles

The flame propagation in an area with obstacles is calculated based on the PDR (Porosity/Distributed Resistance) model. Specifically, the b-Ξ two-equation model is used.

Model geometry

Model geometry near the obstacle (red: obstacle, green: surface area with connected front and back)

In this calculation, variables including the following are used:

- betav: porosity of the volume
- Lobs: Average diameter of the obstacles in the cell (m)
- Aw: Surface area of the obstacle per unit volume (1/m)
- CR: Drag tensor (1/m)
- CT: Turbulence generation parameter (1/m)
- Nv: Number of obstacles in the cell per unit volume (m
^{-2}) - nsv: Tensor. The diagonal component of this tensor represents the number to be subtracted from Nv to obtain the number of obstacles crossed by the flow in each direction.

The PDRFoam specific settings are defined in the file "PDRProperties" in the directory "constant", and the ignition positions are defined in the file "combustionProperties" in the same directory.

The meshes are as follows, and the number of mesh is 8115.

Meshes

Meshes (ground and obstacle surface)

Meshes (cross-sectional surface)

The calculation results are as follows. The figures are rendered by volume rendering.

Temperature from 0 sec to 0.2 sec (T)

Temperature on XZ-plane at 0.03 sec (T)

Temperature on XY-plane at 0.05 sec (T)

We can see that the temperature propagation is blocked by obstacles.

cp -r $FOAM_TUTORIALS/combustion/PDRFoam/flamePropagationWithObstacles flamePropagationWithObstacles

cd flamePropagationWithObstacles

rm -rf 0

cp -r 0.orig 0

blockMesh

changeDictionary

topoSet

PDRMesh -overwrite

PDRFoam

paraFoam

cd flamePropagationWithObstacles

rm -rf 0

cp -r 0.orig 0

blockMesh

changeDictionary

topoSet

PDRMesh -overwrite

PDRFoam

paraFoam

6 minutes 12.8 seconds *Single, Inter(R) Core(TM) i7-2600 CPU @ 3.40GHz 3.40GHz

- OpenFOAM-4.x/applications/solvers/combustion/PDRFoam/PDRFoam.C
- "Numerical Study of the b-Ξ Flame Wrinkling Combustion Model in Oracles Test Rig", J. Aerosp. Technol. Manag. vol.7 no.4 São José dos Campos Oct./Dec. 2015, Guilherme Henrique Santos, Wladimyr Dourado（PDF）