5.1 KiB

Raw Blame History

Problem Definition (v-1.0)

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.

<html>

a view of the Rotary Air-Lock Valve while rotating

particles are colored according to time of insertion

</html>

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.

// 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.

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/shapes the diameter and the material name of the particles are defined.

in caseSetup/shapes file

// 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

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).

// 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);
   // 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.

5.1 KiB Raw Blame History