9.1 KiB
V-blender Simulation (phasicFlow v-1.0)
This tutorial demonstrates the simulation of a V-blender, a common mixing device used in pharmaceutical and powder processing industries. The V-blender consists of a V-shaped vessel that rotates around a horizontal axis, allowing for efficient mixing of particulate materials.
Problem Definition
The simulation represents a V-blender with the following characteristics:
- The blender is initially empty and is filled with two different particle types in sequence
- First layer: Small particles (10 mm diameter) are inserted from the right side
- Second layer: Slightly larger particles (10.1 mm diameter) are inserted from the left side
- The blender begins rotation at t = 3.0 s and continues until t = 10.0 s
- The rotation speed is set to 3.14 rad/s (approximately 0.5 Hz or 30 RPM)
- The simulation runs for a total of 10 seconds
Case Setup
The simulation case setup files are organized in the settings/ and caseSetup/ folders.
Particles Definition
Two particle types are defined in the caseSetup/shapes file:
names (smallSphere largeSphere); // names of particles
diameters (0.01 0.0101); // diameter of particles (m)
materials (lightMat lightMat); // material names for particles
Both particle types share the same material properties but differ slightly in size to allow for visual distinction during mixing.
Particle Insertion
Particles are inserted in two sequential phases, as defined in caseSetup/particleInsertion:
active Yes; // is insertion active -> Yes or No
rightregion
{
timeControl simulationTime; // Controls insertion based on simulation time
regionType cylinder; // Defines a cylindrical insertion region
rate 10000; // Inserts 10,000 particles per second
startTime 0.0; // Starts inserting at t = 0s (beginning of simulation)
endTime 1.0; // Stops inserting at t = 1s
insertionInterval 0.025; // Inserts particles every 0.025s
// (40 insertion events during the 1s period)
cylinderInfo {
// Defines cylinder endpoints and radius
p1 (0.0950615 0.12 0.5011585); // First endpoint coordinates (x,y,z) in meters
p2 (0.1150615 0.12 0.4811585); // Second endpoint coordinates (x,y,z) in meters
radius 0.1; // Cylinder radius in meters
}
setFields {
// Initial properties for inserted particles
velocity realx3 (1.2 0.0 -1.2); // Initial velocity vector (x,y,z) in m/s
// Particles move to the right and downward
}
mixture {
// Particle type distribution
smallSphere 1; // 100% of inserted particles are "smallSphere" type
}
}
leftregion
{
timeControl simulationTime; // Controls insertion based on simulation time
regionType cylinder; // Defines a cylindrical insertion region
rate 10000; // Inserts 10,000 particles per second
startTime 1.5; // Starts inserting at t = 1.5s
// (after the first insertion phase)
endTime 2.5; // Stops inserting at t = 2.5s
insertionInterval 0.025; // Inserts particles every 0.025s
// (40 insertion events during the 1s period)
cylinderInfo {
// Defines cylinder endpoints and radius
p1 (0.7562545 0.12 0.50079); // First endpoint coordinates (x,y,z) in meters
p2 (0.7362545 0.12 0.48079); // Second endpoint coordinates (x,y,z) in meters
radius 0.1; // Cylinder radius in meters
}
setFields {
// Initial properties for inserted particles
velocity realx3 (-1.2 0.0 -1.2); // Initial velocity vector (x,y,z) in m/s
// Particles move to the left and downward
}
mixture {
// Particle type distribution
largeSphere 1; // 100% of inserted particles are "largeSphere" type
}
}
Detailed Explanation of Insertion Parameters
-
rightregionDictionary:- Creates a cylindrical insertion region on the right side of the V-blender
- Active during t=0s to t=1s at the beginning of the simulation
- Particles are inserted from randomly generated positions within the cylinder
- Inserts "smallSphere" particles with 10mm diameter
- Initial velocity (1.2, 0.0, -1.2) m/s directs particles toward the center and bottom of the blender
- 40 insertion events occur (every 0.025s), each adding approximately 250 particles
-
leftregionDictionary:- Creates a symmetrical cylindrical insertion region on the left side of the V-blender
- Active during t=1.5s to t=2.5s, after the first batch of particles has settled
- Inserts "largeSphere" particles with 10.1mm diameter
- Initial velocity (-1.2, 0.0, -1.2) m/s directs particles toward the center and bottom of the blender
- Mirror image of the first insertion but with slightly larger particles
-
Insertion Region Selection:
- Cylindrical insertion regions are positioned above each arm of the V-blender
- This arrangement ensures particles fall naturally into the V-blender without initial overlap
-
Timing Strategy:
- Sequential insertion with a 0.5s gap between phases allows the first batch to settle
- All particles settle for 0.5s after the second insertion (t=2.5s to t=3.0s)
- Blender rotation begins after all particles have settled (t=3.0s)
Geometry and Motion
The V-blender geometry is defined in settings/geometryDict using an STL file:
motionModel rotatingAxis; // motion model: rotating object around an axis
rotatingAxisInfo // information for rotatingAxis motion model
{
rotAxis
{
p1 (0.128228 0.116446 0.297901); // first point for the axis of rotation
p2 (0.722596 0.116459 0.297901); // second point for the axis of rotation
omega 3.14; // rotation speed (rad/s)
startTime 3; // start time of rotation
endTime 10; // end time of rotation
}
}
The blender starts rotating at t = 3.0 s, after both particle types have been inserted and allowed to settle.
Simulation Domain and Boundaries
The simulation domain is defined in settings/domainDict:
globalBox
{
min (-0.1 -0.4 0); // lower corner point of the box
max (0.86 0.6 0.6); // upper corner point of the box
}
All boundaries are set to "exit" type, meaning particles that go outside the domain will be deleted.
Particle Interaction Properties
Material properties and interaction parameters are defined in caseSetup/interaction:
materials (wallMat lightMat); // a list of materials names
densities (1000 1000); // density of materials [kg/m3]
// Contact force models
model
{
contactForceModel nonLinearNonLimited;
rollingFrictionModel normal;
// Material properties
Yeff (1.0e6 1.0e6
1.0e6); // Young modulus [Pa]
Geff (0.8e6 0.8e6
0.8e6); // Shear modulus [Pa]
nu (0.25 0.25
0.25); // Poisson's ratio [-]
en (0.97 0.85
0.97); // coefficient of normal restitution
mu (0.65 0.35
0.65); // dynamic friction
mur (0.1 0.1
0.1); // rolling friction
}
Running the Simulation
To run this simulation, execute the following commands in sequence:
-
First, create the geometry:
geometryPhasicFlow -
Next, initialize the particle system (note: starts with zero particles):
particlesPhasicFlow -
Finally, run the simulation:
sphereGranFlow
The simulation will automatically insert particles according to the defined schedule and begin rotating the V-blender at the specified time.
Visualizing Results
After the simulation completes, you can convert the results to VTK format for visualization:
pFlowToVTK --binary
The VTK files will be stored in a new directory called ./VTK and can be visualized using tools like ParaView or VisIt.
Expected Behavior
During the simulation, you should observe:
- Initial filling with small particles from the right side (0-1s)
- A brief settling period (1-1.5s)
- Filling with large particles from the left side (1.5-2.5s)
- Another settling period (2.5-3s)
- Rotation of the V-blender causing mixing of the two particle types (3-10s)