Update: November 26, 2018

$FOAM_TUTORIALS/compressible/rhoCentralDyMFoam/movingCone

We calculate the flow around a cone-shaped piston moving in a cylindrical tube. The calculation is performed with a simplified model in which a portion of the cylinder is cut out in a wedge shape for one mesh.

The calculations are performed with a density-based solver based on a center-upwind scheme. Therefore, the mass conservation is more accurate, and nonlinear waves such as shock waves can be calculated accurately.

Model

The region "left" is assumed to be open to allow fluid flow in and out, the cylinder surface is set to no-slip wall conditions, and the piston surface (region "movingWall") is set to a fixed flow velocity (0, 0, 0). The piston moves from the region "left" to the region "fixedWall" at 160 m/s. The motion of the mesh is specified in the files constant/dynamicMeshDict and 0/pointMotionUx as follows.

dynamicFvMesh dynamicMotionSolverFvMesh; motionSolverLibs ( "libfvMotionSolvers.so" ); solver velocityComponentLaplacian; velocityComponentLaplacianCoeffs { component x; diffusivity directional (1 200 0); }File: constant/dynamicMeshDict

dimensions [0 1 -1 0 0 0 0]; internalField uniform 0; boundaryField { movingWall { type uniformFixedValue; uniformValue constant 160; } farFieldMoving { type slip; } fixedWall { type uniformFixedValue; uniformValue constant 0; } left { type uniformFixedValue; uniformValue constant 0; } farField { type slip; } back { type wedge; } front { type wedge; } }File: 0/pointMotionUx

The meshes are as follows.

Mesh at time 0

The calculation result is as follows.

Mesh motion

Flow velocity (U)

Flow velocity at final time (U)

Pressure at final time (p)

cp -r $FOAM_TUTORIALS/compressible/rhoCentralDyMFoam/movingCone movingCone

cd movingCone

blockMesh

rhoCentralDyMFoam

paraFoam

cd movingCone

blockMesh

rhoCentralDyMFoam

paraFoam

97.41 seconds *Single, Inter(R) Core(TM) i7-8700 CPU @ 3.20GHz 3.19GHz

- Flow around a cone-shaped piston - XSim
- Flow around a cone-shaped piston moving at high speed - XSim