Cavitation at the narrow flow path (RANS)

Update: July 1, 2017
OpenFOAM 4.x

Case directory

$FOAM_TUTORIALS/multiphase/cavitatingFoam/ras/throttle

Summary

We set a total pressure of 300×105 in the region "inlet" and a static pressure of 100×105 in the region "outlet". The flow of water will be driven from the "inlet" to the "outlet" by the pressure difference and we calculate the flow for 0.002 seconds. The region "walls" are set to the no-slip condition, and the mesh in z-direction is set to one layer to calculate the problem as a two-dimensional.

Model Model

The k-ω SST model is used as turbulence model.

The meshes are as follows, and the number of mesh is 33426.

Mesh (entire) Mesh (entire)
Meshes (narrow channel part) Meshes (narrow channel part)

The calculation result is as follows.

Flow velocity (U)
Flow velocity at 0.0018 sec (U) Flow velocity at 0.0018 sec (U)
Volume ratio of vapor near narrow part at 0.0018 sec (alpha.vapour) Volume ratio of vapor near narrow part at 0.0018 sec (alpha.vapour)
Flow velocity near narrow part at 0.0018 sec (U) Flow velocity near narrow part at 0.0018 sec (U)

We can see that the symmetry of the flow is greatly broken downstream due to the fluctuation of vapor generation at the narrow part.

Commands

cp -r $FOAM_TUTORIALS/multiphase/cavitatingFoam/ras/throttle throttle
cd throttle

blockMesh

cp system/topoSetDict.1 system/topoSetDict
topoSet
refineMesh -dict system/refineMeshDict -overwrite

cp system/topoSetDict.2 system/topoSetDict
topoSet
refineMesh -dict system/refineMeshDict -overwrite

cp system/topoSetDict.3 system/topoSetDict
topoSet
refineMesh -dict system/refineMeshDict -overwrite

cavitatingFoam

paraFoam

Three levels of coarseness are applied to the mesh using the utilities topoSet and refineMesh.

Calculation time

3 hours 25 minutes 33 seconds *Single, Inter(R) Core(TM) i7-2600 CPU @ 3.40GHz 3.40GHz