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Documentation

New Integrated Post-Processor

The new online post-processor integrated into SimScale is compatible with all your old/new projects and simulations that you create.

This document provides a detailed overview of SimScale’s new post-processor. It can be used as a general source of information and also as a follow-along. For easy understanding, an example of a fluid flow through a pipe is used to relate the features to an actual simulation.

If you would like to follow along or play with the various filter settings, make sure to open the sample project below:

Post-Processing

Firstly, when a simulation is successful or has results available, the run dialog box will prompt a ‘Post-process results’ button. Clicking this button or selecting ‘Solution Fields’ in the simulation tree will open the results in the online post-processor.

accessing the post-processing environment in SimScale to start post-process of fluid flow simulation
Figure 1: Click on ‘Post-process results‘ or ‘Solution Fields’ to open the simulation result data in the online post-processor.

Note

The result will only load when you stay in the same tab where the Workbench is opened. The load time for the results will depend on the size of the data. The larger the data, the longer it takes to load results.

Overview

The post-processing environment contains several functions and filters that allow you to obtain a visual representation of the results. The figure below contains an outline of the post-processor:

overview of SimScale's post processor functionalities
Figure 2: Different functionalities available on the SimScale’s online post-processor
  1. Filters creation toolbox: Many filters, such as Cutting plane and Particle trace, are available in the post-processing environment. They are useful to obtain more insights into your results.
  2. Additional tools: To the right of the filters toolbox, you will find useful tools, such as Screenshot and Inspect point, amongst others. An on/off toggle for the legend is also available.
  3. After creating a filter, it will be listed in the Filters box. The filters box allows you to configure each filter, as well as duplicate filters’ settings, and delete existing filters.
  4. Visualization and selection modes toolbox: Here you can change (from left to right) the view and render mode of the geometry, as well as choose the selection mode between Select volume and Select face.
  5. Viewer: This is where you can see results. A series of quick selection tools are accessible by right-clicking on the viewer.
  6. Frame selection toolbox: This part of the post-processor is especially useful in transient simulations. It allows you to navigate through the various result sets that were saved during the simulation run.
  7. The Orientation cube on the bottom-right is helpful to position the camera angle. The home icon adjusts and zoom-fits the model to the screen.

Legend

On the top bar of the post-processor, you can choose to show or hide the Legend, as shown below:

enabling the legend in simscale
Figure 3: Velocity magnitude being observed on the boundaries of the pipe domain using legend toggle.

The post-processor goes through the list of filters, checking which parameters are being analyzed. Only the legend for these parameters will be visible. For example, in the image above the only parameter in the filters is velocity magnitude. Changing the field on the filters will change the legend as well.

The scale bar is highly customizable, including the displayed range, units, and the number of divisions. Figure 4 shows the details:

legend feature in the simscale postprocessor
Figure 4: Using the Legend feature one can decide a scale range, switch between units, and even change between color schemes.
  1. By clicking on the minimum value of the scale range, you can set your custom values.
  2. Likewise, the maximum value of the range can also be changed.
  3. In the drop-down menu, next to the parameter’s name, you can change the units displayed on the scale.
  4. By right-clicking on the scale, you can change the color schemes, number of scale divisions, or even use a continuous scale.

The number of scale divisions is 20 by default. To change the number of scale divisions, right-click on the scale and adjust the Division number accordingly.

division number functionality inside the legend feature in simscale
Figure 5: Number of divisions on the legend scale increased to 40 from a default 20

Statistics and Inspect Point

The Inspect point feature is useful to obtain an accurate read on a specific point of the surface. For example, to inspect the velocity magnitude on the top inlet:

inspect point in simscale postprocessor
Figure 6: With Inspect point you have the freedom to click anywhere on the domain and view the physical quantity.
  1. Enable the Inspect point toggle on the top ribbon.
  2. Click on any point within the top inlet face. In this case, the inlet is defined by a boundary condition, so the velocity is fixed at 1 \(m/s\).

Another very useful option is Statistics. When this option is on, you can obtain detailed information about faces, volumes, and cross-sections (when used alongside cutting planes).

For example, using the Statistics feature, we can easily obtain an average for the velocity magnitude on the outlet. Figure 7 shows the steps:

statistics bulk calculator post-process simscale
Figure 7: The Statistics feature in the post-processor gives you the statistical data like min-max and average of the physical quantity.
  1. Ensure that Statistics is toggled on
  2. Enable the Select face option. Note that, if your Inspect point toggle is still on, you will need to disable it to select a face.
  3. Click on the outlet face to select it. An information box will appear in the viewer, containing minimum and maximum values, averages, integrals, and additional information related to the selected parameter.

Note that the information displayed by the statistics filter is dynamic. You can select various faces and also change the parameter that is being analyzed. To make the information box disappear, you can toggle Statistics off.

Visualization and Selection Modes

The selection modes are designed to quickly select and modify the visualization of the geometry. By right-clicking on the viewer, you will have access to many quick selection options. Some visualization options, such as Hide selection, are also available to hide the selected parts.

Hide selection is especially useful whenever we have an enclosure around the regions of interest (in external aerodynamic simulations, for instance). To make the parts visible again, right-click on the viewer, and select ‘Show all’:

show all to see all the hidden parts of the model in the postprocessor
Figure 8: With a simple right-click one can access a variety of visualization and selection modes. Give it a try.

Cutting Plane

If you would like to follow along or play with the various filter settings, make sure to open the sample project below:

With a Cutting plane filter, you can slice the domain and visualize parameters of interest on the plane. Additional options, such as plotting velocity vectors, are also available.

To create a new filter, select the option of interest in the filters toolbox:

creating a new cutting plane filter
Figure 9: SimScale’s online post-processor supports a variety of filters to enhance the post-processing experience.

Cutting planes are highly customizable. For instance, you can define an Orientation/Position, Opacity, plot Vectors, choose a Coloring option for the cutting plane, among other options.

By adjusting the position and orientation of the cutting plane, taking the orientation cube as a reference, it is possible to obtain valuable insights. To add Vectors to the cutting plane, one can do as follows:

cutting plane filter with vectors in simscale
Figure 10: Configuration of the cutting plane filter to observe velocity magnitude in the yz-plane with vectors. Optimizing the vectors’ settings to your simulation may result in better visualization.

Did you know?

Within the filters panel, you will find a series of options, as in Figure 11:

options inside filter panel simscale
Figure 11: Options like duplicating a filter or hiding or deleting it are possible.

1. By clicking on the icon just right of the filter’s name, you can duplicate it.
2. The dustbin icon deletes a filter.
3. The ON/OFF toggle enables you to show or hide a filter.

Iso Surface and Iso Volume

The Iso surface filter is useful to show cells that match a given variable value. For example, to see where the velocity magnitude is exactly 1 \(m/s\) an Iso surface filter, with the following configuration can be created:

iso surface filter simscale
Figure 12: Iso surface filter shows only regions with the same Iso value, velocity magnitude of 1 m/s in this case.

Within Iso scalar and Iso value, the user decides the criteria for highlighting the cells. With Coloring, you can choose a parameter color for the cells that satisfy the criteria.

The Iso volume filter works the same way. However, instead of defining a single Iso value, the user defines an Iso value range to highlight the cells.

For example, to highlight the regions with gauge pressure levels between -2000 and -100 \(Pa\) one should proceed as follows:

iso volumes filter in simscale
Figure 13: Iso volume filter shows only volume regions within the defines the same Iso value range, pressure [-2000, -100] \(Pa\) in this case.

To have a clearer view of where the highlighted regions are, it’s possible to enable Parts Color with transparency. The image below shows the details:

iso volumes with transparency
Figure 14: By showing the Parts Color with transparency, we can get more insights about the highlighted iso volume cells.

Particle Trace

A Particle trace filter generates streamlines from a seed face. They can be useful to observe recirculation spots and flow patterns, allowing us to improve the designs.

Configuring a particle trace is very simple. After creating the filter, the user needs to select a seed face, from where the streamlines are generated. Oftentimes, the inlets and outlets are good candidates for seed face. With Pick Position enabled, you will be able to select one of the inlets as a seed face, as in Figure 15:

particle trace filter simscale
Figure 15: Defining a Particle Trace filter. Pick up a position for the seed face as shown with arrows.

It is possible to duplicate the first particle trace filter, and set a second trace from the top inlet:

multiple particle traces
Figure 16: Defining multiple particle traces is possible by creating new filters or duplicating existing particle trace filters.

Did you know?

The Particle Trace filter is highly customizable, allowing the configuration of the following settings:

  • The number of seeds, in horizontal and vertical direction
  • Spacing between two streamlines within the seed face
  • Any of the parameters can be selected for the coloring of the traces. Alternatively, one can also choose to use a solid color
  • For the visual representation of the traces, the user can choose Cylinders, Comets, or Spheres
  • The size of the streamlines can be adjusted
  • With Trace both directions, the streamlines are generated both upstream and downstream of the seed face
  • Depending on the representation of the traces, more set up options may appear. The Num pulses configuration is available for spheres and comets, and represents the number of particle sets in the domain at a given time.
  • For comets, it is also possible to define the relative comet length. This way, each comet leaves a trail relative to its velocity, as seen in the figure below.

particle trace spheres and comets configuration
Figure 17: With this configuration, 5 groups (or Pulses) of comets are visible in the domain. The length of each comet is controlled by its velocity and the Relative comet length.

Animation

The animation filter is often used on two occasions:

  • In combination with a particle trace filter
  • To animate the results of a transient analysis
animation filter in simscale
Figure 18: Creating an animation of the multiple particle traces created in the previous section. Please ensure that the Animation type is set to Particle trace.

After setting the Animation type to Particle Trace, we can simply click on the ‘Play’ button, to generate an animation of the streamlines. Note that you can change the number of Steps, to control the number of frames of the animation.

animation of particle traces
Animation 1: Particle trace animation from different inlets in the SimScale’s online post-processor.

Custom Camera Position

Simulating a project and drafting a professional report might require recreating the same angles and screenshots for all the visual results. To take advantage of this consistency in your animations and images use the custom camera position. This feature can be seen at the top left of the orientation cube.

custom camera feature location
Figure 19: You can easily access the custom camera position menu next to the orientation cube using the post-processing interface.

To learn more about this handy feature refer to our knowledge base article.

Troubleshooting

In case of problems with the post-processor, please reset it to the default settings. To do that, simply right-click on the ‘Reset’ button:

resetting to default values in the online postprocessor
Figure 20: Resetting the post-processor to default will solve most of the post-processing issues.

Legacy Interface

As default, the Solution Fields loads in the New Beta Interface. However, you can still access the Legacy Interface. To switch between the New Beta Interface and the Legacy Interface, simply right-click on Solution Fields and select ‘Open in legacy interface’.

how to load the simulation results in the legacy interface in the simscale platform
Figure 21: The default post-processing viewer is the new beta interface, but you can switch to the legacy interface.

Feeling Inspired?

If you would like to use these post-processing filters and tools in different projects, make sure to check our step-by-step tutorials. Each tutorial contains a post-processing section with new ideas and combinations of filters.

Furthermore, it is also possible to readily post-process thousands of projects from other users in the Public Projects section.

Last updated: November 26th, 2021

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