F-DEMPack Tutorial 2: Annular pipe

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==Introduction==
 
==Introduction==
 
Before starting with this tutorial, the user is strongly encouraged to follow
 
Before starting with this tutorial, the user is strongly encouraged to follow
the [[D-DEMPack Tutorial 2: Conveyor belt]] to get a feeling of how the problem type works, and in particular the DEM section. This tutorial will focus mainly in the Fluid section and its particularities.
+
the [[G-DEMPack Tutorial 1: Conveyor belt]] to get a feeling of how the problem type works, and in particular the DEM section. This tutorial will focus mainly in the Fluid section and its particularities.
 
+
  
 
==Geometry==
 
==Geometry==
 
The process should start by creating a new geometry from scratch, by modifying an existing one or by opening a finished one. It is assumed that the user already knows how to do this procedure so no details will be given about it.
 
The process should start by creating a new geometry from scratch, by modifying an existing one or by opening a finished one. It is assumed that the user already knows how to do this procedure so no details will be given about it.
  
In this tutorial, a simple geometry was created for the sake of simplicity. The idea is to understand all the steps involved in the problem type. The user must start by downloading the file [[File:F DEMPack2 Tutorial 6.gid.zip]], which contains the geometry and mesh of the proposed geometry. This file has already created the groups that will be used in the simulation.
+
In this tutorial, a simple geometry was created for the sake of simplicity. The idea is to understand all the steps involved in the problem type. The user must start by downloading the file [[File:F_DEMPack_Tutorial_1.gid.zip]], which contains the geometry and mesh of the proposed geometry. This file has already created the groups that will be used in the simulation.
  
 
[[File:F-DEM_Tutorial6_Geometry.png|300px]]
 
[[File:F-DEM_Tutorial6_Geometry.png|300px]]
  
 
The geometry of study consists of an annular tube through which a flux of an intermediate viscosity mud passes. An inlet creating DEM particles with time is located in the base of the annular pipe.
 
The geometry of study consists of an annular tube through which a flux of an intermediate viscosity mud passes. An inlet creating DEM particles with time is located in the base of the annular pipe.
 
  
 
==Groups==
 
==Groups==
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The first section of the menu is General Application Data. Within this section the user can specify the simulation parameters, the coupling parameters between both subdomains -fluid and DEM particles-, and some postprocess results options. A deeper explanation of those parameters can be found in [[F-DEMPack2 manual]].
 
The first section of the menu is General Application Data. Within this section the user can specify the simulation parameters, the coupling parameters between both subdomains -fluid and DEM particles-, and some postprocess results options. A deeper explanation of those parameters can be found in [[F-DEMPack2 manual]].
  
[[File:F-DEM Tutorial6 DEMGeneralOpt.PNG]]
+
[[File:F-DEM Tutorial6 GeneralData.PNG]]
  
 
The previous screenshot shows the reference parameters that have been used in this particular case.
 
The previous screenshot shows the reference parameters that have been used in this particular case.
Line 73: Line 71:
  
 
===Solution strategy===
 
===Solution strategy===
Other advanced options that that the user can specify are those related to the ''Solution strategy'' and ''DEM-Specific Results''. More information about these submenus can be found in [[F-DEMPack2 manual]].
+
Other advanced options that the user can specify are those related to the ''Solution strategy'' and ''DEM-Specific Results''. More information about these submenus can be found in [[F-DEMPack2 manual]].
  
 
[[File:F-DEM Tutorial6 DEMSolStrategy.PNG]]
 
[[File:F-DEM Tutorial6 DEMSolStrategy.PNG]]
Line 82: Line 80:
 
The first two submenus are related to the solver type for the fluid part and its parameters, and the third sumbenu allows the user to enter the delta time to use in the computations of the fluid as well as the step for the divergence clearance.
 
The first two submenus are related to the solver type for the fluid part and its parameters, and the third sumbenu allows the user to enter the delta time to use in the computations of the fluid as well as the step for the divergence clearance.
  
The default parameters in the problem type gave good results in this particular case.
+
The default parameters on the next figure gave good results in this particular case.
  
 
[[File:F-DEM Tutorial6 FluidData1.PNG]]
 
[[File:F-DEM Tutorial6 FluidData1.PNG]]
  
 
===Properties===
 
===Properties===
So we first start by setting the values of the main time variables by going to Fluid > Problem_parameters. See Figure 9 for details on this tree.
+
The user can set the fluid properties by assigning them to the Fluid material previously created. To do this, right-click on ''Properties'' and choose New. A New Property window will appear below. ''Fluid1'' can be selected on the ''Material'' drop-down menu.
 
+
We can then set the fluid properties by assigning them to the Water material previously created. To do this, right-click on Properties and choose New. A New Property window will appear below. We choose Water on the label next to Material and click Ok. The properties of the fluid in the problem are those of the Water material. See the next figure for details.
+
  
 
[[File:F-DEM Tutorial6 FluidProperties.PNG]] [[File:F-DEM Tutorial6 FluidProperties2.PNG]]
 
[[File:F-DEM Tutorial6 FluidProperties.PNG]] [[File:F-DEM Tutorial6 FluidProperties2.PNG]]
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===Elements===
 
===Elements===
  
The next step is to identify the fluid elements amongst all the existing geometric entities. We can do so by going to Elements and right-click on Fluid. As before, we must choose New and a window will open at the bottom. On the Group tab, choose Fluid and click Ok. The elements are properly assigned. Figure 11 shows the process.
+
The next step is to identify the fluid elements amongst all the existing geometric entities. This can be done by going to Elements and right-click on Fluid. As before, if the user clicks on ''New'' a window will open at the bottom. The working fluid can be selected on the ''Group'' drop-down menu. The elements are properly assigned after clicking on ''Ok''.
 +
 
 +
*''Important remarks''
 +
**'''Make sure a property has been created before assigning the fluid element.'''
  
 
[[File:F-DEM Tutorial6 FluidElements.PNG]] [[File:F-DEM Tutorial6 FluidElements2.PNG]]
 
[[File:F-DEM Tutorial6 FluidElements.PNG]] [[File:F-DEM Tutorial6 FluidElements2.PNG]]
  
 
===Initial conditions===
 
===Initial conditions===
We follow the same procedure to assign the initial conditions to the problem. In this case, we give the mass of fluid an initial vertical velocity field. The picture that follows shows the process.
+
The same procedure is followed to assign the initial conditions to the problem. In this case, an initial vertical velocity field of 1.5 m/s  is given to the mass of fluid. The picture that follows shows the process.
  
[[File:F-DEM Tutorial6 FluidInitialCond.PNG]]
+
[[File:DEM 2 tutorial swimming Initial Conditions.png|200px]]
  
 
====Boundary conditions====
 
====Boundary conditions====
Now we can proceed to assign the boundary conditions. We begin by setting the inlet velocity of the mass of fluid. To do so, we right-click on Boundary_conditions > Inlet_velocity and create the new inlet condition. We fill in the fields with the desired values, relate the Group with the corresponding entity and click Ok. See Figure 13 for details.
+
Regarding the boundary conditions, an inlet velocity of 1.5 m/s is proposed to be set in the entrance of the annular pipe. This can be done by right-clicking on ''Boundary_conditions'' >'' Inlet_velocity'' and creating the new inlet condition over the desired group. As seen in the next picture, a velocity of 1.5 is specified in the vertical direction.
 +
 
 +
A similar process is followed to impose the pressure boundary condition. In this example it is assigned a null pressure value at the top surface.
 +
 
 +
To finish with the boundary conditions, slip conditions are informed in the domain. In this case, no-slip conditions have been chosen on the cylinder walls. As shown in the figure that follows, the user must assign this property to the appropriate layer, in this case the outer and inner cylinders of the annular pipe.
  
 
[[File:F-DEM Tutorial6 BoundCondFluid.PNG]]
 
[[File:F-DEM Tutorial6 BoundCondFluid.PNG]]
  
We proceed in the same for imposing the pressure boundary condition. In this example we assigned a null pressure value at the top surface. The process is the same as before and it is sketched in the figure that follows.
+
==Meshing and Running==
 +
The last step before launching the calculation is to mesh the domain. All the mesh characteristics are predefined on the downloaded model, so the user can proceed to mesh by typing Ctrl+G or by unfolding the ''Mesh'' menu on the top of GiD and clicking on ''Generate Mesh...''. A size of 0.05 has been selected for the mesh.
  
The same process applies for the slip conditions in the domain. In this case, we chose no-slip condition on the cylinder walls. As shown in the figure that follows, we assigned this property to the appropriate layer, in this case the box.
+
[[File:F-DEM Tutorial6 Mesh.png|300px]]
  
==DEM-Fluid Interaction Settings==
+
==Calculate==
 +
After the geometry is successfully meshed and the case is saved, the user is now ready to launch the calculation. To do this, the user must go to ''Calculate > Calculate'' or press the ''Run the simulation'' button in the interface. The next figure shows the Process Management section of the interface.
  
 +
[[File:F-DEM Tutorial6 ProcessMenu.PNG]]
  
==Meshing and Running==
+
The first button inside the red square opens the process control window, the second one runs the simulation, the third one gives information about the calculations and the last one stops the process.
The last step before launching the calculation is to mesh the domain. The user must take into account that two different meshers should be used when using the DEM Element section. Firstly, a triangle-based mesher for should be employed for the surfaces, that will be discretized in a standard FEM fashion and, secondly, a sphere mesher for the groups made up of DEM particles.
+
  
By default, GiD uses a tetrahedra/triangles based mesher, so the user should manually select the geometrical entities that will be meshed using the sphere mesher. These entities will be volumes that will be set as meshed with spheres by going to Mesh > Element_type > Sphere, selecting the desired group and pressing Esc to finish. The user can modify or tweak the sphere mesher settings by going to Utilities > Preferences > Meshing > Sphere_mesher.
 
  
The next step is to set the mesh size of the different parts of the geometry. For the entities meshed with spheres, the assigned number would correspond with the average diameter of the particles. To assign these sizes, the user should go to Mesh > Unstructured > Assign_size_on_volumes for the particles entities and to Mesh > Unstructured > Assign_size_on_points (lines, surfaces) for the inlets or DEM/FEM groups. As a general rule, after selecting the corresponding layers, the user must press Esc to confirm and exit the selection process.
+
==Results==
 +
Once the program starts writing results, the user can shift to the Postprocess in order to analyze the obtained results. After clicking on ''Open multiple files'' and selecting the desired group of files to be opened, the user can observe the sequence of results with time by using the ''Window > Animate'' utility. Next figures show a succession of results after running the sample case.
  
It is important to note that the purpose of this size-setting procedure is to endow some particular entities with a specific mesh size. Nevertheless, when most of the domain has a certain mesh size, no previous size-setting procedure should be applied on it. GiD will obtain this mesh size when the user enters a default value at the beginning of the meshing process. This meshing operation can be accessed by clicking on Mesh > Generate_mesh, entering the desired size and pressing OK.
+
[[File:F-DEM Tutorial6 Post1.PNG|200px]] [[File:F-DEM Tutorial6 Post2.PNG|180px]] [[File:F-DEM Tutorial6 Post3.PNG|180px]] [[File:F-DEM Tutorial6 Post4.PNG|200px]]
  
Finally, to confirm if all sizes were correctly assigned, the user can go to Mesh > Draw > Sizes > All_types to check graphically the assignation. The following figure shows the obtained mesh for the sample case.
+
It is also possible to print several physical results as, for example, the velocity field of the particles or the fluid pressure distrubution on a determinated step of time. To do this, the user must click on ''View results > Display vectors > VELOCITY > |VELOCITY|'', and ''View results > Contour Fill > PRESSURE > |VELOCITY|''.
 +
 
 +
[[File:F-DEM Tutorial6 PostVel.PNG|300px]] [[File:F-DEM_Tutorial6_PostPres.PNG|300px]]
  
==Calculate==
 
So after the geometry was successfully meshed and the case saved, the user is now ready to launch the calculation. To do this, the user must go to Calculate > Calculate or press the Run the simulation button in the interface. Figure 26 shows the buttons in the Process Management section of the interface. The button inside the black square runs the simulation, the one inside the red one gives information about the calculations and the one in green stops the process.
 
  
==Results==
 
Once the program starts writing results, the user can shift to the Postprocess in order to analyze the obtained results. After clicking on Open multiple files and selecting the desired group of files to be opened, the user can observe the sequence of results with time by using the Animate utility. The Results animation window is available when pressing Ctrl-m. Figure 27 shows a succession of results after running the sample case.
 
  
It is also possible to print several physical results as, for example, the velocity field. To do this, the user must click on View_results > Display_vectors > VELOCITY > |VELOCITY|. A result like the one showing in Figure 28 should be obtained. More information can be obtained on the use of GiD by pressing F1.
+
==Additional DEM Tutorials==
 +
Other tutorials can be found [http://kratos-wiki.cimne.upc.edu/index.php/DEMPack_Tutorials here].

Latest revision as of 10:34, 19 November 2018

Contents

Introduction

Before starting with this tutorial, the user is strongly encouraged to follow the G-DEMPack Tutorial 1: Conveyor belt to get a feeling of how the problem type works, and in particular the DEM section. This tutorial will focus mainly in the Fluid section and its particularities.

Geometry

The process should start by creating a new geometry from scratch, by modifying an existing one or by opening a finished one. It is assumed that the user already knows how to do this procedure so no details will be given about it.

In this tutorial, a simple geometry was created for the sake of simplicity. The idea is to understand all the steps involved in the problem type. The user must start by downloading the file File:F DEMPack Tutorial 1.gid.zip, which contains the geometry and mesh of the proposed geometry. This file has already created the groups that will be used in the simulation.

F-DEM Tutorial6 Geometry.png

The geometry of study consists of an annular tube through which a flux of an intermediate viscosity mud passes. An inlet creating DEM particles with time is located in the base of the annular pipe.

Groups

The downloaded file has already created the groups that will be used in the simulation.

F-DEM Tutorial6 Groups.jpg.png

In this sample case, the following five groups were created: Dem_inlet, Fluid, Inlet, No_slip and Outlet. The lower circle (surface) would be the Inlet, the smaller one just on top of it was the DEM_Inlet, the circle at the top would represent the Outlet, the No_slip would be the walls of the cylinder and, finally, the volume named Fluid would constitute the mass of fluid.


Materials

Fluid properties

We will continue by defining the properties of the fluid in the simulation. We just have to click on the icon showing in the next figure to open the menus and in particular the Materials tab:

F-DEM Tutorial6 MatIcon.png

To begin inserting the fluid properties, we click on Fluid and then on the plus button at the bottom of the window to add a new Fluid material.

F-DEM Tutorial6 AddMat.png

The next figure shows the details of the fluid material parameters that have been used in this example. To fill in or modify the value of the parameters, just unfold the General and Fluid submenus and double-click on the corresponding current data. The following data corresponds to an intermediate viscosity mud.

F-DEM Tutorial6 FluidMat.PNG

DEM properties

The same process can be followed, in this case, for the DEM material. We unfold the DEM-Defaultmaterial submenu at the bottom of the same window and fill the fields with the appropriate data. See Figure 6.

F-DEM Tutorial6 DEMMat.PNG


General Application Data

We now need to tell the program the model characteristics: boundary and initial conditions, inlet options, time considerations, etc. To begin filling all this data, we just click on the Model menu located at the left of the Materials tab and the Model Properties window will show up. This menu can be accessed also by clicking on the icon showing in the next figure:

F-DEM Tutorial6 PropsIcon.png

The first section of the menu is General Application Data. Within this section the user can specify the simulation parameters, the coupling parameters between both subdomains -fluid and DEM particles-, and some postprocess results options. A deeper explanation of those parameters can be found in F-DEMPack2 manual.

F-DEM Tutorial6 GeneralData.PNG

The previous screenshot shows the reference parameters that have been used in this particular case.


DEM Entities

The entities and conditions in relation to the DEM part of the problem are already preassigned so the user does not have to bother and can concentrate on the fluid aspects and details of the simulation. Nevertheless, figures showing the details on the DEM parts will be added here for the sake of completion and as a reference should the user lose these settings or in the case of have any problem when loading the file.

DEM-FEM wall group

The outer and inner cylinders are defined as walls in this section (No-Slip group). No motion is imposed on any of them.

F-DEM Tutorial6 DEM-FEM wall.PNG

Inlet DEM group

The annular surface over the base of the annurar pipe is set as the inlet of DEM particles. A total of 1000 particles per second are generated with an initial velocity of 1.5 m/s on the longitudinal direction of the pipe. The DEM material of the particles is specified in this submenu, as well as their diameter.

F-DEM Tutorial6 Inlet.PNG

General options

This section is devoted to set the limits of the bounding box, the gravity vector and some advanced features. The figure that follows shows the chosen parameters.

F-DEM Tutorial6 DEMGeneralOpt.PNG

Solution strategy

Other advanced options that the user can specify are those related to the Solution strategy and DEM-Specific Results. More information about these submenus can be found in F-DEMPack2 manual.

F-DEM Tutorial6 DEMSolStrategy.PNG

Fluid

This section contains the information about the properties of the fluids, the different existing fluid elements and, when necessary, their assigned conditions. It also has some parameters in relation to the settings of the fluid solver.

The first two submenus are related to the solver type for the fluid part and its parameters, and the third sumbenu allows the user to enter the delta time to use in the computations of the fluid as well as the step for the divergence clearance.

The default parameters on the next figure gave good results in this particular case.

F-DEM Tutorial6 FluidData1.PNG

Properties

The user can set the fluid properties by assigning them to the Fluid material previously created. To do this, right-click on Properties and choose New. A New Property window will appear below. Fluid1 can be selected on the Material drop-down menu.

F-DEM Tutorial6 FluidProperties.PNG F-DEM Tutorial6 FluidProperties2.PNG

Elements

The next step is to identify the fluid elements amongst all the existing geometric entities. This can be done by going to Elements and right-click on Fluid. As before, if the user clicks on New a window will open at the bottom. The working fluid can be selected on the Group drop-down menu. The elements are properly assigned after clicking on Ok.

  • Important remarks
    • Make sure a property has been created before assigning the fluid element.

F-DEM Tutorial6 FluidElements.PNG F-DEM Tutorial6 FluidElements2.PNG

Initial conditions

The same procedure is followed to assign the initial conditions to the problem. In this case, an initial vertical velocity field of 1.5 m/s is given to the mass of fluid. The picture that follows shows the process.

DEM 2 tutorial swimming Initial Conditions.png

Boundary conditions

Regarding the boundary conditions, an inlet velocity of 1.5 m/s is proposed to be set in the entrance of the annular pipe. This can be done by right-clicking on Boundary_conditions > Inlet_velocity and creating the new inlet condition over the desired group. As seen in the next picture, a velocity of 1.5 is specified in the vertical direction.

A similar process is followed to impose the pressure boundary condition. In this example it is assigned a null pressure value at the top surface.

To finish with the boundary conditions, slip conditions are informed in the domain. In this case, no-slip conditions have been chosen on the cylinder walls. As shown in the figure that follows, the user must assign this property to the appropriate layer, in this case the outer and inner cylinders of the annular pipe.

F-DEM Tutorial6 BoundCondFluid.PNG

Meshing and Running

The last step before launching the calculation is to mesh the domain. All the mesh characteristics are predefined on the downloaded model, so the user can proceed to mesh by typing Ctrl+G or by unfolding the Mesh menu on the top of GiD and clicking on Generate Mesh.... A size of 0.05 has been selected for the mesh.

F-DEM Tutorial6 Mesh.png

Calculate

After the geometry is successfully meshed and the case is saved, the user is now ready to launch the calculation. To do this, the user must go to Calculate > Calculate or press the Run the simulation button in the interface. The next figure shows the Process Management section of the interface.

F-DEM Tutorial6 ProcessMenu.PNG

The first button inside the red square opens the process control window, the second one runs the simulation, the third one gives information about the calculations and the last one stops the process.


Results

Once the program starts writing results, the user can shift to the Postprocess in order to analyze the obtained results. After clicking on Open multiple files and selecting the desired group of files to be opened, the user can observe the sequence of results with time by using the Window > Animate utility. Next figures show a succession of results after running the sample case.

F-DEM Tutorial6 Post1.PNG F-DEM Tutorial6 Post2.PNG F-DEM Tutorial6 Post3.PNG F-DEM Tutorial6 Post4.PNG

It is also possible to print several physical results as, for example, the velocity field of the particles or the fluid pressure distrubution on a determinated step of time. To do this, the user must click on View results > Display vectors > VELOCITY > |VELOCITY|, and View results > Contour Fill > PRESSURE > |VELOCITY|.

F-DEM Tutorial6 PostVel.PNG F-DEM Tutorial6 PostPres.PNG


Additional DEM Tutorials

Other tutorials can be found here.

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