5.8 KiB
Problem definition
A rotating drum is randomly filled with two particle sizes and rotated to observe particle segregation. The focus of this tutorial is to show how to use the preprocessing tool particlesPhasicFlow to create the initial mixture of small and large particles.
Note: It is supposed that you have reviewed simulating a rotating drum tutorial before starting this tutorial.
Case setup
In the file caseSetup/sphereShape two particle types with the names smallSphere and largeSphere and the diameters 3 and 5 mm are defined.
Simulation case setup files can be found in tutorials/sphereGranFlow folder.
Shape definition
In the file caseSetup/sphereShape two particle types with the names smallSphere and largeSphere and the diameters 3 and 5 mm are defined.
names (smallSphere largeSphere); // names of shapes
diameters (0.003 0.005); // diameter of shapes (m)
materials (prop1 prop1); // material names for shapes
Positioning and initial mixture
In the dictionary positionParticles located in file settings/particlesDict, 30000 particles are located in a cylindrical region. These particles are positioned in order along z, x and then y axis with 0.005 m distance between their centers.
// positions particles
positionParticles
{
method ordered; // other options: random or empty
orderedInfo
{
diameter 0.005; // minimum space between centers of particles
numPoints 30000; // number of particles in the simulation
axisOrder (z x y); // axis order for filling the space with particles
}
regionType cylinder; // other options: box and sphere
cylinder // cylinder region for positioning particles
{
p1 (0.0 0.0 0.003); // begin point of cylinder axis (m m m)
p2 (0.0 0.0 0.097); // end point of cylinder axis (m m m)
radius 0.117; // radius of cylinder (m)
}
}
In the setFields dictionary, located in the settings/particlesDict file, you define the initial velocity, acceleration, rotVelocity and shapeName fields for all 30000 particles in the simulation. In the selectors' dictionary, you can select subsets of particles and set the field value for those subsets. The selectRangeselector is defined in theshapeAssignesubdictionary. It defines a range withbegin, endandstrideto select particles. And in thefieldValue` subdictionary the field values for selected particles are set (any number of field values can be set here).
Note: Other selectors are: selectBox that selects particles inside a box and randomSelect that selects particles randomly from a given index range.
setFields
{
/*
Default value for fields defined for particles
These fields should always be defined for simulations with
spherical particles.
*/
defaultValue
{
velocity realx3 (0 0 0); // linear velocity (m/s)
acceleration realx3 (0 0 0); // linear acceleration (m/s2)
rotVelocity realx3 (0 0 0); // rotational velocity (rad/s)
shapeName word smallSphere; // name of the particle shape
}
selectors
{
shapeAssigne
{
selector stridedRange; // other options: box, cylinder, sphere, randomPoints
stridedRangeInfo
{
begin 0; // begin index of points
end 30000; // end index of points
stride 3; // stride for selector
}
fieldValue // fields that the selector is applied to
{
/*
sets shapeName of the selected points to largeSphere
*/
shapeName word largeSphere;
}
}
}
Running the simulation
Enter the following command in terminal:
> geometryPhasicFlow
> particlesPhasicFlow
> sphereGranFlow
Note on using particlesPhasicFlow
Each executable in PhasicFlow comes with some command line options that you can see them by using flag -h in front of that command.
> particlesPhasicFlow -h prints out the following output:
Usage: particlesPhasicFlow [OPTIONS]
Options:
-h,--help Help for using createParticles of phasicFlow v-0.1
-v,--version Program version information
--discription What does this app do?
--positionParticles-only Exectue the positionParticles part only and store the created pointStructure in the time folder.
--setFields-only Exectue the setFields part only. Read the pointStructure from time folder and setFields and save the result in the same time folder.
so, with flag --setFields-only, you can execute the setFields part of particlesDict. Now suppose that you have a simulation case which proceeded up to 2 seconds and for any reason you want to change some field value at time 3 s and continue the simulation from 3 s. To this end, you need to change startTime in settings dictionary to 3, execute particlesPhasicFlow --setFields-only, and start the simulation.