# PhasicFlow: Problem Definition

Problem Definition

The problem is to simulate a rotating drum with the diameter 0.24 m, the length 0.1 m and 6 Baffles, rotating at 15 rpm. This drum is filled with 20000 Particles.The timestep for integration is 0.00001 s. There are 2 types of Particles in this drum each are beining inserted during simulation to fill the drum.

- 12500 Particles with 4 mm diameter, at the rate of 12500 particles/s for 1 sec.
- 7500 Particles with 5mm diameter, at the rate of 7500 particles/s for 1 sec.

<html> <body>

a view of the drum while rotating
<img src="https://github.com/PhasicFlow/phasicFlow/blob/media/media/rotatingDrumBffl.gif", width=700px>

</body> </html>

# Setting up the Case

As it has been explained in the previous cases, the simulation case setup is based on text-based scripts. Here, the simulation case setup are sotred in three folders: `caseSetup`, `setting` and `stl` (see the above folders).

## Defining small and large particles

Then in the `caseSetup/sphereShape` the diameter and the material name of the particles are defined. Two sizes are defined: 4 and 5 mm.
{C++}
// names of shapes
names (smallSphere largeSphere);
// diameter of shapes (m)
diameters (0.004 0.005);
// material names for shapes
materials (lightMat heavyMat);

## Particle Insertion

In this case we have two region for inserting our particles. In the both region we define rate of insertion, start and end time of insertion, information for the volume of the space throught which particles are being inserted. The insertion phase in the simulation is performed between times 0 and 1 seconds.
For example, for the insertion region for inserting light particles is shown below.
in caseSetup/particleInsertion file
{C++}
// Right Layer Region
layerrightregion
{
// type of insertion region
type cylinderRegion;
// insertion rate (particles/s)
rate 12500;
// Start time of LightParticles insertion (s)
startTime 0;
// End time of LightParticles insertion (s)
endTime 1;
// Time Interval of LightParticles insertion (s)
interval 0.025;
cylinderRegionInfo
{
// Coordinates of cylinderRegion (m,m,m)
p2 (-0.15 0.25 0.05);
p1 (-0.15 0.24 0.05);
// radius of cylinder (m)
radius 0.035;
}
}

## Interaction between particles and walls

In `caseSetup/interaction` file, material names and properties and interaction parameters are defined: interaction between the particles and the shell of rotating drum. Since we are defining 3 materials for simulation, the interaction matrix is 3x3, while we are only required to enter upper-triangle elements (interactions are symetric).
{C++}
// a list of materials names
materials (lightMat heavyMat wallMat);
// density of materials [kg/m3]
densities (1000 1500 2500);
/*
Property (lightMat-lightMat lightMat-heavyMat lightMat-wallMat
heavyMat-heavyMat heavyMat-wallMat
wallMat-wallMat );
*/
// Young modulus [Pa]
Yeff (1.0e6 1.0e6 1.0e6
1.0e6 1.0e6
1.0e6);
// Shear modulus [Pa]
Geff (0.8e6 0.8e6 0.8e6
0.8e6 0.8e6
0.8e6);
// Poisson's ratio [-]
nu (0.25 0.25 0.25
0.25 0.25
0.25);
// coefficient of normal restitution
en (0.97 0.97 0.85
0.97 0.85
1.00);
// coefficient of tangential restitution
et (1.0 1.0 1.0
1.0 1.0
1.0);
// dynamic friction
mu (0.65 0.65 0.35
0.65 0.35
0.35);
// rolling friction
mur (0.1 0.1 0.1
0.1 0.1
0.1);

## Settings

### Geometry

In the `settings/geometryDict` file, the geometry and axis of rotation is defined for the drum. The geometry is composed of a body, front and rear ends.
{C++}
surfaces
{
body
{
// type of the wall
type stlWall;
// file name in stl folder
file Body.stl;
// material name of this wall
material wallMat;
// motion component name
motion rotAxis;
}
/* This is a Cylinder Wall at the rear of cylinder */
rearEnd
{
// type of the wall
type cylinderWall;
// first point for the axis of rotation
p1 (-0.1974 0.2269 -0.001);
// second point for the axis of rotation
p2 (-0.1974 0.2269 0.0);
// Radius of p1
radius1 0.0001;
// Radius of p2
radius2 0.12;
// material name of the wall
material wallMat;
// motion component name
motion rotAxis;
}
/* This a cylinder Wall at the front of Cylinder */
frontEnd
{
// type of the wall
type cylinderWall;
// first point for the axis of rotation
p1 (-0.1974 0.2269 0.0989);
// second point for the axis of rotation
p2 (-0.1974 0.2269 0.0990);
// Radius of p1
radius1 0.0001;
// Radius of p2
radius2 0.12;
// material name of the wall
material wallMat;
// motion component name
motion rotAxis;
}
}

### Rotating Axis Info

In this part of `geometryDict` the information of rotating axis and speed of rotation are defined. The start of rotation is at 2 s. The first 2 seconds of simulation is for allowing particles to settle donw in the drum.
{C++}
rotatingAxisMotionInfo
{
rotAxis
{
// first point for the axis of rotation
p1 (-0.1974 0.2269 0);
// second point for the axis of rotation
p2 (-0.1974 0.2269 0.1);
// rotation speed (rad/s) => 15 rpm
omega 2.38733;
// Start time of Geometry Rotating
startTime 2;
// End time of Geometry Rotating
endTime 9.5;
}
}

## Performing Simulation

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 storred in ./VTK folder.