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A new screwConveyor tutorial
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@ -1,23 +1,24 @@
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# Simulating a screw conveyor {#screwConveyor}
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## Problem definition
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The problem is to simulate a screw conveyorwith the diameter 0.2 m and the length 1 m and 20 cm pitch. It is filled with 30,000 4-mm spherical particles. The timestep for integration is 0.00001 s.
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<div align="center"><b>
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a view of rotating drum
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# Simulating a Screw Conveyor
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![]()
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</b></div>
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## Problem Definition
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The problem is to simulate a screw conveyor with a diameter of 0.2 m and a length of 1 m with a variable pitch. It is filled with 10 mm and 9 mm spherical particles. The timestep for integration is 0.00002 s. Particles are inserted from the top of the feeder at a rate of 2800 particles/s. The number composition of large and small particles is 2:1.
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<div align="center"><b>
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A view of the screw conveyor simulation
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</b>
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<img src="./screw.jpeg" style="width: 400px;">
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</div>
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***
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## Setting up the case
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PhasicFlow simulation case setup is based on the text-based scripts that we provide in two folders located in the simulation case folder: `settings` and `caseSetup` (You can find the case setup files in the above folders.
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All the commands should be entered in the terminal while the current working directory is the simulation case folder (at the top of the `caseSetup` and `settings`).
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## Setting Up the Case
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### Creating particles
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PhasicFlow simulation case setup is based on the text-based scripts provided in two folders located in the simulation case folder: `settings` and `caseSetup`. All commands should be entered in the terminal while the current working directory is the simulation case folder (at the top level of `caseSetup` and `settings`).
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Open the file `settings/particlesDict`. Two dictionaries, `positionParticles` and `setFields` position particles and set the field values for the particles.
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In dictionary `positionParticles`, the positioning `method` is `positionOrdered`, which position particles in order in the space defined by `box`. `box` space is defined by two corner points `min` and `max`. In dictionary `positionOrderedInfo`, `numPoints` defines number of particles; `diameter`, the distance between two adjacent particles, and `axisOrder` defines the axis order for filling the space by particles.
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### Creating Particles
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Open the file `settings/particlesDict`. Two dictionaries, `positionParticles` and `setFields`, position particles and set the field values for the particles. In the dictionary `positionParticles`, the positioning `method` is `empty`, which means that there are no particles in the simulation at the start.
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<div align="center">
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in <b>settings/particlesDict</b> file
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@ -26,20 +27,20 @@ in <b>settings/particlesDict</b> file
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```C++
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positionParticles
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{
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// A list of options are: ordered, random
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method empty; // creates the required fields with zero particles (empty).
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maxNumberOfParticles 50000; // maximum number of particles in the simulation
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mortonSorting Yes; // perform initial sorting based on morton code?
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mortonSorting Yes; // perform initial sorting based on morton
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}
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```
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Enter the following command in the terminal to create the particles and store them in `0` folder.
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Enter the following command in the terminal to create the particles and store them in the `0` folder:
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`> particlesPhasicFlow`
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### Creating geometry
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In file `settings/geometryDict` , you can provide information for creating geometry. Each simulation should have a `motionModel` that defines a model for moving the surfaces in the simulation. `rotatingAxisMotion` model defines a fixed axis which rotates around itself. The dictionary `rotAxis` defines an motion component with `p1` and `p2` as the end points of the axis and `omega` as the rotation speed in rad/s. You can define more than one motion component in a simulation.
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### Creating Geometry
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In the file `settings/geometryDict`, you can provide information for creating geometry. Each simulation should have a `motionModel` that defines a model for moving the surfaces in the simulation. The `rotatingAxis` model defines a fixed axis which rotates around itself. The dictionary `rotAxis` defines a motion component with `p1` and `p2` as the endpoints of the axis and `omega` as the rotation speed in rad/s. You can define more than one motion component in a simulation.
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<div align="center">
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in <b>settings/geometryDict</b> file
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@ -54,16 +55,16 @@ rotatingAxisMotionInfo
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{
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rotAxis
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{
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p1 (1.09635 0.2010556 0.22313511); // first point for the axis of rotation
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p2 (0.0957492 0.201556 0.22313511); // second point for the axis of rotation
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omega 3; // rotation speed (rad/s)
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startTime 5;
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endTime 30;
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p1 (0 0 0.0); // first point for the axis of rotation
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p2 (0 0 1.0); // second point for the axis of rotation
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omega 3.14; // rotation speed (rad/s)
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startTime 1; // when t>1 s, rotation starts
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endTime 30; // when t>30 s, rotation stops
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}
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}
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```
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In the dictionary `surfaces` you can define all the surfaces (shell) in the simulation. Two main options are available: built-in geometries in PhasicFlow, and providing surfaces with stl file. Here we use built-in geometries. In `cylinder` dictionary, a cylindrical shell with end helix, `material` name `prop1`, `motion` component `none` is defined. `helix` define plane helix at center of cylindrical shell, `material` name `prop1` and `motion` component `rotAxis`.'rotAxis' is use for helix because it is rotating and 'none' is use for shell because It is motionless.
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In the dictionary `surfaces`, you can define all the surfaces in the simulation. Two main options are available: built-in geometries in PhasicFlow, and providing surfaces with an STL file (ASCII format). Here we use `stlWall` as a method to provide the surface information through STL files. In the `shell` dictionary, `material` is set to `prop1` and `motion` is set to `none` (meaning this surface is fixed). `helix` defines the screw at the center of the cylindrical part of the shell. For this surface, `material` is set to `prop1` and `motion` is set to `rotAxis`.
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<div align="center">
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in <b>settings/geometryDict</b> file
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@ -75,8 +76,8 @@ surfaces
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helix
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{
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type stlWall; // type of the wall
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file helix.stl; // file name in stl folder
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material prop1; // material name of this wall
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file screw.stl; // file name in stl folder
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material prop1; // material name of this wall
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motion rotAxis; // motion component name
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}
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@ -84,20 +85,19 @@ surfaces
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{
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type stlWall; // type of the wall
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file shell.stl; // file name in stl folder
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material prop1; // material name of this wall
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motion none; // motion component name
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material prop1; // material name of this wall
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motion none; // this surface is not moving ==> none
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}
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}
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```
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Enter the following command in the terminal to create the geometry and store it in `0/geometry` folder.
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Enter the following command in the terminal to create the geometry and store it in the `0/geometry` folder:
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`> geometryPhasicFlow`
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### Defining properties and interactions
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In the file `caseSetup/interaction` , you find properties of materials. `materials` defines a list of material names in the simulation and `densities` sets the corresponding density of each material name. model dictionary defines the interaction model for particle-particle and particle-wall interactions. `contactForceModel` selects the model for mechanical contacts (here nonlinear model with limited tangential displacement) and `rollingFrictionModel` selects the model for calculating rolling friction. Other required prosperities should be defined in this dictionary.
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### Defining Properties and Interactions
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In the file `caseSetup/interaction`, you will find properties of materials. `materials` defines a list of material names in the simulation and `densities` sets the corresponding density of each material name. The `model` dictionary defines the interaction model for particle-particle and particle-wall interactions. `contactForceModel` selects the model for mechanical contacts (here nonlinear model with limited tangential displacement) and `rollingFrictionModel` selects the model for calculating rolling friction. Other required properties should be defined in this dictionary.
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<div align="center">
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in <b>caseSetup/interaction</b> file
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@ -105,13 +105,14 @@ in <b>caseSetup/interaction</b> file
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```C++
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materials (prop1); // a list of materials names
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densities (1000.0); // density of materials [kg/m3]
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densities (2300.0); // density of materials [kg/m3]
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contactListType sortedContactList;
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model
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{
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contactForceModel nonLinearNonLimited;
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contactForceModel nonLinearNonLimited;
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rollingFrictionModel normal;
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Yeff (1.0e6); // Young modulus [Pa]
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@ -120,18 +121,15 @@ model
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nu (0.25); // Poisson's ratio [-]
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en (0.7); // coefficient of normal restitution
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et (1.0); // coefficient of tangential restitution
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en (0.8); // coefficient of normal restitution
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mu (0.3); // dynamic friction
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mur (0.1); // rolling friction
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mur (0.2); // rolling friction
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}
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```
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Dictionary `contactSearch` sets the methods for particle-particle and particle-wall contact search. `method` specifies the algorithm for finding neighbor list for particle-particle contacts and `wallMapping` shows how particles are mapped onto walls for finding neighbor list for particle-wall contacts. `updateFrequency` sets the frequency for updating neighbor list and `sizeRatio` sets the size of enlarged cells (with respect to particle diameter) for finding neighbor list. Larger `sizeRatio` include more particles in the neighbor list and you require to update it less frequent.
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The dictionary `contactSearch` sets the methods for broad search. `method` specifies the algorithm for finding the neighbor list for particle-particle contacts. `updateInterval` sets the intervals (in terms of the number of iterations) between each occurrence of updating the neighbor list, and `sizeRatio` sets the size of enlarged cells (with respect to particle diameter) for finding the neighbor list. A larger `sizeRatio` includes more particles in the neighbor list, requiring less frequent updates.
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<div align="center">
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in <b>caseSetup/interaction</b> file
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@ -140,69 +138,61 @@ in <b>caseSetup/interaction</b> file
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```C++
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contactSearch
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{
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method NBS; // method for broad search particle-particle
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wallMapping cellMapping; // method for broad search particle-wall
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method NBS; // method for broad search
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updateInterval 10;
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NBSInfo
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{
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updateFrequency 10; // each 20 timesteps, update neighbor list
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sizeRatio 1.1; // bounding box size to particle diameter (max)
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}
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sizeRatio 1.1;
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cellMappingInfo
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{
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updateFrequency 10; // each 20 timesteps, update neighbor list
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cellExtent 0.6; // bounding box for particle-wall search (> 0.5)
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}
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cellExtent 0.55;
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adjustableBox Yes;
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}
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```
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In the file `caseSetup/sphereShape`, you can define a list of `names` for shapes (`shapeName` in particle field), a list of diameters for shapes and their `properties` names.
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In the file `caseSetup/shapes`, you can define a list of `names` for shapes, a list of `diameters` for shapes, and their `materials` names.
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<div align="center">
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in <b>caseSetup/sphereShape</b> file
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in <b>caseSetup/shapes</b> file
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</div>
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```C++
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names (sphere1); // names of shapes
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diameters (0.01); // diameter of shapes
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materials (prop1); // material names for shapes
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names (sphere1 sphere2); // names of shapes
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diameters (0.01 0.009); // diameter of shapes
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materials (prop1 prop1); // material names for shapes
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```
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Other settings for the simulation can be set in file `settings/settingsDict`. The dictionary `domain` defines the a rectangular bounding box with two corner points for the simulation. Each particle that gets out of this box, will be deleted automatically.
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Other settings for the simulation can be set in the file `settings/settingsDict`. The dictionary `domain` defines a rectangular bounding box with two corner points for the simulation. Each particle that gets out of this box will be deleted automatically.
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<div align="center">
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in <b>settings/settingsDict</b> file
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</div>
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```C++
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dt 0.0001; // time step for integration (s)
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startTime 0; // start time for simulation
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endTime 20; // end time for simulation
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saveInterval 0.05; // time interval for saving the simulation
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timePrecision 6; // maximum number of digits for time folder
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g (0 -9.8 0); // gravity vector (m/s2)
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dt 0.00002; // time step for integration (s)
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domain
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{
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min (0.0 -0.06 0.001);
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max (1.2 1 0.5);
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}
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startTime 0; // start time for simulation
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integrationMethod AdamsBashforth3; // integration method
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endTime 20; // end time for simulation
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timersReport Yes; // report timers?
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saveInterval 0.025; // time interval for saving the simulation
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timersReportInterval 0.01; // time interval for reporting timers
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timePrecision 4; // maximum number of digits for time folder
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g (0 -9.8 0); // gravity vector (m/s2)
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writeFormat binary; // field files will be saved in binary format
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...
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```
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## Running the case
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The solver for this simulation is `sphereGranFlow`. Enter the following command in the terminal. Depending on the computational power, it may take a few minutes to a few hours to complete.
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## Running the Case
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The solver for this simulation is `sphereGranFlow`. Enter the following command in the terminal. Depending on the computational power, it may take a few minutes to a few hours to complete:
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`> sphereGranFlow`
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## Post processing
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After finishing the simulation, you can render the results in Paraview. To convert the results to VTK format, just enter the following command in the terminal. This will converts all the results (particles and geometry) to VTK format and store them in folder `VTK/`.
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## Post Processing
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`> pFlowToVTK`
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After finishing the simulation, you can render the results in ParaView. To convert the results to VTK format, enter the following command in the terminal. This will convert all the results (particles and geometry) to VTK format and store them in the `VTK/` folder:
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`> pFlowToVTK --binary -f diameter id velocity`
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