# Problem Definition
The problem is to simulate a Rotary Air-Lock Valve. The external diameter of rotor is about 21 cm. There is one type of particle in this simulation. Particles are inserted into the inlet of the valve from t=**0** s.
* **28000** particles with **5 mm** diameter are inserted into the valve with the rate of **4000 particles/s**.
* The rotor starts its rotation at t = 1.25 s at the rate of 2.1 rad/s.
a view of the Rotary Air-Lock Valve while rotating
particles are colored according to time of insertion
# Setting up the Case
As it has been explained in the previous simulations, the simulation case setup is based on text-based scripts. Here, the simulation case setup files are stored into three folders: `caseSetup`, `setting`, and `stl` (see the above folders). See next the section for more information on how we can setup the geometry and its rotation.
## Geometry
### Defining rotation axis
In file `settings/geometryDict` the information of rotating axis of rotor and its speed of rotation are defined. The rotation starts at t = **1.25 s** and ends at t = **7 s**.
```C++
// information for rotatingAxisMotion motion model
rotatingAxisMotionInfo
{
rotAxis
{
// first point for the axis of rotation
p1 (0.561547 0.372714 0.000);
// second point for the axis of rotation
p2 (0.561547 0.372714 0.010);
// rotation speed (rad/s)
omega 2.1;
// Start time of Geometry Rotating (s)
startTime 1.25;
// End time of Geometry Rotating (s)
endTime 7;
}
}
```
### Surfaces
In `settings/geometryDict` file, the surfaces component are defined to form a Rotating Air-Lock Valve. All surface components are supplied in stl file format. All stl files should be stored under 'stl' folder.
```C++
surfaces
{
gear
{
// type of the wall
type stlWall;
// file name in stl folder
file gear.stl;
// material name of this wall
material wallMat;
// motion component name
motion rotAxis;
}
surfaces
{
// type of the wall
type stlWall;
// file name in stl folder
file surfaces.stl;
// material name of this wall
material wallMat;
// motion component name
motion none;
}
```
## Defining particles
### Diameter and material of spheres
In the `caseSetup/sphereShape` the diameter and the material name of the particles are defined.
in caseSetup/sphereShape file
```C++
// names of shapes
names (sphere);
// diameter of shapes
diameters (0.005);
// material names for shapes
materials (sphereMat);
```
### Insertion of Particles
Insertion of particles starts from t = 0 s and ends at t = 7 s. A box is defined for the port from which particles are being inderted. The rate of insertion is 4000 particles per second.
in settings/particleInsertion file
```C++
topRegion
{
// type of insertion region
type boxRegion;
// insertion rate (particles/s)
rate 4000;
// Start time of Particles insertion (s)
startTime 0;
// End time of Particles insertion (s)
endTime 7;
// Time interval between each insertion (s)
interval 0.025;
// Coordinates of BoxRegion (m,m,m)
boxRegionInfo
{
min ( 0.48 0.58 0.01 ); // (m,m,m)
max ( 0.64 0.59 0.05 ); // (m,m,m)
}
setFields
{
// initial velocity of inserted particles
velocity realx3 (0.0 -0.6 0.0);
}
mixture
{
sphere 1;
}
}
```
## 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 2x2 (interactions are symmetric).
```C++
// a list of materials names
materials (sphereMat wallMat);
// density of materials [kg/m3]
densities (1000 2500);
contactListType sortedContactList;
model
{
contactForceModel nonLinearNonLimited;
rollingFrictionModel normal;
/*
Property (sphereMat-sphereMat sphereMat-wallMat
wallMat-wallMat);
*/
// Young modulus [Pa]
Yeff (1.0e6 1.0e6
1.0e6);
// Shear modulus [Pa]
Geff (0.8e6 0.8e6
0.8e6);
// Poisson's ratio [-]
nu (0.25 0.25
0.25);
// coefficient of normal restitution
en (0.7 0.8
1.0);
// coefficient of tangential restitution
et (1.0 1.0
1.0);
// dynamic friction
mu (0.3 0.35
0.35);
// rolling friction
mur (0.1 0.1
0.1);
}
```
# Performing simulation and seeing 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 (here the simulaiton has no particle at the beginning).
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. 