Tests and Examples

In this section, we present 4 test cases and 2 examples to verify our tool and show some of its capabilities. Moreover, you will learn how to submit different analyses in the following section.

Test case 1: 1D flow

The first analysis is an approximately 1D flow, which has the following

To use this mesh in an analysis, first create one and in the Mesh section, upload 1D_band.unv from here.

You should see the longside of the mesh in the X-direction. Confirm the mesh and set the viscosity to 0.01 Pa.s. Create a preform with 0.02 m thickness and 0.2 volume fraction. Set K11 to 1e-8 m^2 and K12 and K22 equal to zero to have a 1D diffusion problem and assign the created preform to allDomain with no rotation. Now, for boundary conditions, choose the left edge and assign an Inlet with 100000 pascals Pressure. Then, choose the right edge and assign a Outlet condition with zero pressure. The other edge-group '2sides' would have a 'Wall' boundary condition. You can modify the boundary condition if you have not assign it properly or you want to compare different cases. Now, create a Step with default parameters and proceed to Submit webpage. Check the details in the Submit section and Submit job if everything looks ok. You can move to previous sections for modifications. You can also download the Configuration file or XML file of the analysis in the Submit page.

When the analysis is finished, you should see All CVs are filled!. We have different criteria for terminating the analysis. If you want all of the medium to be filled with resin, the termination criteria should be set to Fill everywhere, however, this might result in a stall analysis, if you end up with a dry region in the preform. To prevent this case, we use a threshold for the maximum number of stalled analysis, which is based on the change of saturation over consecutive iterations.

Click on Go to results. Composite on Clouds uses Paraview to visualize the results. The software will load in the results section and you can choose different outputs by clicking on the paper button on the upper left corner. Some of the results are described here:

• Analysis output

  • fillingmedium.xdmf contains pressure distribution, velocity profile, and saturation over the entire domain during the analysis. The time-steps are based on the output time-step in the Step section.
  • flowfrontvstime.pvd shows the flow front position at different times in a single graph. The graph is very useful when you want to see which part of the preform is going to be filled any time. Toggle on the legend of this graph and you will see that the maximum filling time is around 2.2 seconds. We will compare this to the analytical result of this problem to verify the code.

• Debugging output

  • boundaries.pvd shows markers assigned to different boundaries. The boundaries are marked with consecutive integers starting from one. Zero is assigned to internal boundaries and 99 is assigned to the flow-front.

  • domains.pvd shows the available cells in each time-step. The pressure equation in FEniCS is solved in the red cells.

  • materials.pvd shows markers assigned to different sections of the medium. You can check here if the sections are well-implemented in your mesh.

Verification

The 1D flow in a porous medium is governed by Darcy's equation. We can find the filling time by integrating the two sides of the equation.

Using the material properties mentioned above, the analytical filling time will be 2.25 seconds which is fairly similar to the filling time found with the code (2.11 seconds).

Test case 2: Anisotropic permeability

The second analysis is a 2D simulation on a rectangle with anisotropic permeability. The geometry is:

To use this mesh in an analysis, first create one and in the Mesh section, upload 2D_rectangle.unv from here.

Now, assign 0.02 Pa.s for viscosity and create a preform with the following properties:

In the Section page, assign the preform to AllDomain and set the Rotate value to 45 degrees. This will turn the preform 45 degrees with respect to the X-axis.

Choose Inlet condition for the left edge and Outlet condition for the right edge. Set Wall conditions for the other two edges. The Wall condition prevents resin from going out of the domain, while the Outlet condition just reinforces pressure on the edge. Thus, you will have resin leakage on those boundaries. If you do not specify a value for the Outlet pressure, the solver assumes that the flow-front has zero gage pressure.

Create a Step with default values and Submit Job.

You should see a maximum of 525 control volumes. When the analysis is finished, go to the Results section.

Test case 3: Quarter of a disk

To use this mesh in an analysis, first create one and in the Mesh section, upload 2D_quarterDisk.unv from here.

3D Semicircle

3D B-Pillar

depicted from here