8.7 KiB
Problem Definition (v-1.0)
The problem is to simulate a double pedestal blender (mixer) with diameters of 0.03 m and 0.1 m, length of 0.3 m, rotating at 28 rpm. This mixer is filled with 24000 particles. The integration time step is 0.00001 s. There is one type of particle in this mixer. Particles are positioned to fill the mixer before the simulation starts.
- 24000 particles with 5 mm diameter are positioned, in order, and let to be settled under gravity. After settling particles, this blender starts to rotate at t=1s.
Setting up the Case
As explained in the previous cases, the simulation case setup is based on text-based scripts. Here, the simulation case setup files are stored in two folders: caseSetup, setting (see the folders above). Unlike the previous cases, this case does not have a stl file and the surfaces are defined based on the built-in utilities in phasicFlow. See the next section for more information on how to set up the geometry and its rotation.
Geometry
Defining rotation axis
In file settings/geometryDict the information of rotating axis and speed of rotation are defined. The rotation of this blender starts at time=0.5 s and ends at time=9.5 s.
// information for rotatingAxisMotion motion model
rotatingAxisInfo
{
axisOfRotation
{
p1 (-0.1 0.0 0.15); // first point for the axis of rotation
p2 ( 0.1 0.0 0.15); // second point for the axis of rotation
omega 1.5708; // rotation speed ==> 15 rad/s
// Start time of Geometry Rotating (s)
startTime 0.5;
// End time of Geometry Rotating (s)
endTime 9.5;
}
}
Surfaces
In settings/geometryDict file, the surfaces and motion component of each surface are defined to form a rotating tote-blender. The geometry is composed of top and bottom cylinders, top and bottom cones, a cylindrical shell and top and bottom Gates.
surfaces
{
topGate
{
// type of wall
type cylinderWall;
// begin point of cylinder axis
p1 (0.0 0.0 0.3);
// end point of cylinder axis
p2 (0.0 0.0 0.301);
// radius at p1
radius1 0.03;
// radius at p2
radius2 0.0001;
// material of wall
material solidProperty;
// motion component name
motion axisOfRotation;
}
topCylinder
{
// type of the wall
type cylinderWall;
// begin point of cylinder axis
p1 (0.0 0.0 0.28);
// end point of cylinder axis
p2 (0.0 0.0 0.3);
// radius at p1
radius1 0.03;
// radius at p2
radius2 0.03;
// number of divisions
resolution 36;
// material name of this wall
material solidProperty;
// motion component name
motion axisOfRotation;
}
coneShelltop
{
// type of the wall
type cylinderWall;
// begin point of cylinder axis
p1 (0.0 0.0 0.2);
// end point of cylinder axis
p2 (0.0 0.0 0.28);
// radius at p1
radius1 0.1;
// radius at p2
radius2 0.03;
// number of divisions
resolution 36;
// material name of this wall
material solidProperty;
// motion component name
motion axisOfRotation;
}
cylinderShell
{
// type of the wall
type cylinderWall;
// begin point of cylinder axis
p1 (0.0 0.0 0.1);
// end point of cylinder axis
p2 (0.0 0.0 0.2);
// radius at p1
radius1 0.1;
// radius at p2
radius2 0.1;
// number of divisions
resolution 36;
// material name of this wall
material solidProperty;
// motion component name
motion axisOfRotation;
}
coneShelldown
{
// type of the wall
type cylinderWall;
// begin point of cylinder axis
p1 (0.0 0.0 0.02);
// end point of cylinder axis
p2 (0.0 0.0 0.1);
// radius at p1
radius1 0.03;
// radius at p2
radius2 0.1;
// number of divisions
resolution 36;
// material name of this wall
material solidProperty;
// motion component name
motion axisOfRotation;
}
bottomCylinder
{
// type of the wall
type cylinderWall;
// begin point of cylinder axis
p1 (0.0 0.0 0.0);
// end point of cylinder axis
p2 (0.0 0.0 0.02);
// radius at p1
radius1 0.03;
// radius at p2
radius2 0.03;
// number of divisions
resolution 36;
// material name of this wall
material solidProperty;
// motion component name
motion axisOfRotation;
}
exitGate
{
// type of the wall
type cylinderWall;
// begin point of cylinder axis
p1 (0.0 0.0 -0.001);
// end point of cylinder axis
p2 (0.0 0.0 0.0);
// radius at p1
radius1 0.03;
// radius at p2
radius2 0.0001;
// number of divisions
resolution 36;
// material name of this wall
material solidProperty;
// motion component name
motion axisOfRotation;
}
}
Defining particles
Diameter and material of spheres
In the caseSetup/shapes the diameter and the material name of the particles are defined.
// name of shapes
names (sphere1);
// diameter of shapes (m)
diameters (0.005);
// material name for shapes
materials (solidProperty);
Particle positioning before start of simulation
Particles are positioned before the start of simulation. The positioning can be ordered or random. Here we use ordered positioning. 24000 particles are positioned in a cylinderical region inside the tote-blender.
// positions particles
positionParticles
{
// ordered positioning
method ordered;
// perform initial sorting based on morton code
mortonSorting Yes;
orderedInfo
{
// minimum space between centers of particles
diameter 0.005;
// number of particles in the simulation
numPoints 24000;
// axis order for filling the space with particles
axisOrder (x y z);
}
regionType cylinder; // other options: box and sphere
cylinderInfo // cylinder for positioning particles
{
p1 (0.0 0.0 0.09); // Coordinates of bottom cylinderRegion (m,m,m)
p2 (0.0 0.0 0.21); // Coordinates of top cylinderRegion (m,m,m)
radius 0.09; // radius of cylinder
}
}
Interaction between particles
In caseSetup/interaction file, material names and properties and interaction parameters are defined. Since we are defining 1 material type in the simulation, the interaction matrix is 1x1 (interactions are symmetric).
// a list of materials names
materials (solidProperty);
// density of materials [kg/m3]
densities (1000.0);
contactListType sortedContactList;
model
{
contactForceModel nonLinearNonLimited;
rollingFrictionModel normal;
/*
Property (solidProperty-solidProperty);
*/
// Young modulus [Pa]
Yeff (1.0e6);
// Shear modulus [Pa]
Geff (0.8e6);
// Poisson's ratio [-]
nu (0.25);
// coefficient of normal restitution
en (0.7);
// dynamic friction
mu (0.3);
// rolling friction
mur (0.1);
}
Performing Simulation and previewing the results
To perform simulations, enter the following commands one after another in the terminal.
Enter particlesPhasicFlow command to create the initial fields for particles.
Enter geometryPhasicFlow command to create the geometry.
At last, enter sphereGranFlow command to start the simulation.
After finishing the simulation, you can use pFlowtoVTK to convert the results into vtk format stored in ./VTK folder.