Merge branch 'main' of github.com:PhasicFlow/phasicFlow into main
This commit is contained in:
Hamidreza Norouzi
commit
30d5d81656
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# Problem definition
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A rotating drum with two particle sizes is randomly filled and let it rotate to see the segregation of particles.
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The focus of this tutorial is to show how to use the pre-processing tool, `particlesPhasicFlow`, to create the initial mixture of small and large particles.
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**Note:** It is supposed that you have reviewed [simulating a rotating drum](https://github.com/PhasicFlow/phasicFlow/wiki/Simulating-a-rotating-drum) tutorial before starting this tutorial.
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<div align="center"><b>
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a view of the rotating drum with small and large particles after 7 seconds of rotation</b>
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</div>
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<div align="center">
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<img src="https://github.com/PhasicFlow/phasicFlow/blob/media/media/rotating-drum-binary-system.png" width="400">
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</div>
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***
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# Case setup
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PhasicFlow simulation case setup is based on the text-based files that we provide in two folders located in the simulation case folder: `settings` and `caseSetup`. Here we will have a look at some important files and the rest can be found in the tutorial folder of this case setup.
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[Simulation case setup files can be found in tutorials/sphereGranFlow folder.](https://github.com/PhasicFlow/phasicFlow/tree/main/tutorials/sphereGranFlow/binarySystemOfParticles)
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### Shape definition
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In file `caseSetup/sphereShape`, two particle types with names `smallSphere` and `largeSphere` and diameters 3 and 5 mm are defined.
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<div align="center">
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in <b>caseSetup/sphereShape</b> file
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</div>
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```C++
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names (smallSphere largeSphere); // names of shapes
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diameters (0.003 0.005); // diameter of shapes (m)
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materials (prop1 prop1); // material names for shapes
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```
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### Positioning and initial mixture
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In 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.
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<div align="center">
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in <b>settings/particlesDict</b> file
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</div>
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```C++
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// positions particles
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positionParticles
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{
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method positionOrdered; // ordered positioning
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maxNumberOfParticles 30001; // maximum number of particles in the simulation
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mortonSorting Yes; // perform initial sorting based on morton code?
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cylinder // cylinder region for positioning particles
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{
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p1 (0.0 0.0 0.003); // begin point of cylinder axis (m m m)
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p2 (0.0 0.0 0.097); // end point of cylinder axis (m m m)
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radius 0.117; // radius of cylinder (m)
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}
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positionOrderedInfo
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{
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diameter 0.005; // minimum space between centers of particles
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numPoints 30000; // number of particles in the simulation
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axisOrder (z x y); // axis order for filling the space with particles
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}
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}
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```
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In dictionary `setFields` located in file `settings/particlesDict`, you define the initial `velocity`, `acceleration`, `rotVelocity`, and `shapeName` fields for all 30000 particles in the simulation. In `selectors` dictionary, you can select subsets of particles and set the field value for these subsets. In `shapeAssigne` sub-dictionary, the `selectRange` selector is defined. It defines a range with `begin` (begin index), `end` (end index) and `stride` to select particles. And in `fieldValue` sub-dictionary, the fields values for selected particles are set (any number of field values can be set here).
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**Note:** Other selectors are: `selectBox` that selects particles inside a box and `randomSelect` that selects particles randomly from a given index range.
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<div align="center">
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in <b>settings/particlesDict</b> file
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</div>
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```C++
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setFields
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{
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/*
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Default value for fields defined for particles
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These fields should always be defined for simulations with
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spherical particles.*/
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defaultValue
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{
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velocity realx3 (0 0 0); // linear velocity (m/s)
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acceleration realx3 (0 0 0); // linear acceleration (m/s2)
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rotVelocity realx3 (0 0 0); // rotational velocity (rad/s)
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shapeName word smallSphere; // name of the particle shape
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}
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selectors
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{
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shapeAssigne
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{
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selector selectRange; // type of point selector
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selectRangeInfo
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{
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begin 0; // begin index of points
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end 30000; // end index of points
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stride 3; // stride for selector
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}
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fieldValue // fields that the selector is applied to
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{
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/*
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sets shapeName of the selected points to largeSphere*/
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shapeName word largeSphere;
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}
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}
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}
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```
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# Running the simulation
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Enter the following command in terminal:
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`> geometryPhasicFlow`
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`> particlesPhasicFlow`
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`> sphereGranFlow`
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### Note on using particlesPhasicFlow
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Each executable in PhasicFlow comes with some command line options that you can see them by using flag `-h` in front of that command.
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`> particlesPhasicFlow -h` prints out the following output:
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```
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Usage: particlesPhasicFlow [OPTIONS]
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Options:
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-h,--help Help for using createParticles of phasicFlow v-0.1
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-v,--version Program version information
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--discription What does this app do?
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--positionParticles-only Exectue the positionParticles part only and store the created pointStructure in the time folder.
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--setFields-only Exectue the setFields part only. Read the pointStructure from time folder and setFields and save the result in the same time folder.
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```
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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.
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## Problem definition
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The problem is to simulate a rotating drum with the diameter 0.24 m and the length 0.1 m rotating at 11.6 rpm. 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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</b></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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### 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.
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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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<div align="center">
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in <b>settings/particlesDict</b> file
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</div>
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```C++
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positionParticles
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{
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method positionOrdered; // ordered positioning
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maxNumberOfParticles 40000; // maximum number of particles in the simulation
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mortonSorting Yes; // perform initial sorting based on morton code?
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box // box for positioning particles
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{
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min (-0.08 -0.08 0.015); // lower corner point of the box
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max ( 0.08 0.08 0.098); // upper corner point of the box
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}
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positionOrderedInfo
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{
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diameter 0.004; // minimum space between centers of particles
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numPoints 30000; // number of particles in the simulation
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axisOrder (z y x); // axis order for filling the space with particles
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}
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}
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```
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In dictionary `setFields`, dictionary `defaultValue` defines the initial value for particle fields (here, `velocity`, `acceleration`, `rotVelocity`, and `shapeName`). Note that `shapeName` field should be consistent with the name of shape that you later set for shapes (here one shape with name `sphere1`).
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<div align="center">
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in <b>settings/particlesDict</b> file
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</div>
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```C++
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setFields
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{
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defaultValue
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{
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velocity realx3 (0 0 0); // linear velocity (m/s)
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acceleration realx3 (0 0 0); // linear acceleration (m/s2)
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rotVelocity realx3 (0 0 0); // rotational velocity (rad/s)
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shapeName word sphere1; // name of the particle shape
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}
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selectors
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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 particles and store them in `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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<div align="center">
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in <b>settings/geometryDict</b> file
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</div>
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```C++
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motionModel rotatingAxisMotion;
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.
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.
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.
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rotatingAxisMotionInfo
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{
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rotAxis
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{
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p1 (0.0 0.0 0.0); // first point for the axis of rotation
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p2 (0.0 0.0 1.0); // second point for the axis of rotation
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omega 1.214; // rotation speed (rad/s)
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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 (walls) 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 radii, `radius1` and `radius2`, axis end points `p1` and `p2`, `material` name `prop1`, `motion` component `rotAxis` is defined. `resolution` sets number of division for the cylinder shell. `wall1` and `wall2` define two plane walls at two ends of cylindrical shell with coplanar corner points `p1`, `p2`, `p3`, and `p4`, `material` name `prop1` and `motion` component `rotAxis`.
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<div align="center">
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in <b>settings/geometryDict</b> file
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</div>
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```C++
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surfaces
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{
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cylinder
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{
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type cylinderWall; // type of the wall
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p1 (0.0 0.0 0.0); // begin point of cylinder axis
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p2 (0.0 0.0 0.1); // end point of cylinder axis
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radius1 0.12; // radius at p1
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radius2 0.12; // radius at p2
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resolution 24; // number of divisions
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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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wall1
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{
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type planeWall; // type of the wall
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p1 (-0.12 -0.12 0.0); // first point of the wall
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p2 ( 0.12 -0.12 0.0); // second point
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p3 ( 0.12 0.12 0.0); // third point
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p4 (-0.12 0.12 0.0); // fourth point
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material prop1; // material name of the wall
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motion rotAxis; // motion component name
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}
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wall2
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{
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type planeWall;
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p1 (-0.12 -0.12 0.1);
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p2 ( 0.12 -0.12 0.1);
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p3 ( 0.12 0.12 0.1);
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p4 (-0.12 0.12 0.1);
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material prop1;
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motion rotAxis;
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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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`> 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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<div align="center">
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in <b>caseSetup/interaction</b> file
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</div>
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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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.
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.
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.
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model
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{
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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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Geff (0.8e6); // Shear modulus [Pa]
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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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mu (0.3); // dynamic friction
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mur (0.1); // 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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<div align="center">
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in <b>caseSetup/interaction</b> file
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</div>
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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 cellsSimple; // method for broad search particle-wall
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NBSInfo
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{
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updateFrequency 20; // 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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cellsSimpleInfo
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{
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updateFrequency 20; // each 20 timesteps, update neighbor list
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cellExtent 0.7; // bounding box for particle-wall search (> 0.5)
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}
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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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<div align="center">
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in <b>caseSetup/sphereShape</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 (0.004); // diameter of shapes
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materials (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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<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 0.00001; // time step for integration (s)
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startTime 0; // start time for simulation
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endTime 10; // end time for simulation
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saveInterval 0.1; // 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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domain
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{
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min (-0.12 -0.12 0);
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max (0.12 0.12 0.11);
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}
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integrationMethod AdamsBashforth2; // integration method
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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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`> 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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`> pFlowToVTK`
|
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Loading…
Reference in New Issue