Overview

This tutorial provides a step by step guide to setting up and running a simulation involving the EM120D explosive with cylindrical confinement within the RateStick module of the Cambridge Numerical Solutions (CNS) platform.

Accessing the ‘Simulations’ page

After logging on to your CNS account, you will be directed to your ‘Modules’ page which will display the list of CNS modules that you are subscribed to. Clicking on the ‘CNS-Ratestick’ module will take you to the corresponding ‘Simulations’ page.

The ‘Modules’ page of your CNS account.

Creating the simulation

On the ‘Simulations’ page, click on the ‘New simulation’ button to create a simulation within the ‘Default’ folder.

Note: For more information on creating and managing simulations, see the tutorial ‘RateStick: Simulation management’.

Creating a new simulation with the ‘Default’ folder.

In the ‘New simulation’ window which opens:

1. In the ‘Simulation name’ field, enter the name that you would like to use for the simulation (e.g. ‘EM120D Steel’).
2. Select ‘None’ in the ‘Use simulation template’ dropdown menu. For more information on simulation templates, see the tutorial ‘RateStick: Simulation from a Template’.
3. Click on the ‘Create button’.

‘New simulation’ window.

Your newly created simulation project will now appear within your ‘Default’ folder. Click on the simulation name to enter the ‘Settings’ page for the simulation.

Accessing the ‘Settings’ page for a simulation.

Configuring the simulation

Select ‘EM120D’ from the list of explosives that appear below and to the left of the simulation schematic. The corresponding material properties are shown in the ‘Explosive material properties’ box.

Explosive material selection.

Select ‘Steel’ from the list of confiners. The corresponding material properties are displayed in the ‘Confiner material properties’ box.

Confiner material selection.

Navigate to the ‘Parameters’ settings pane either via the settings dropdown menu or the ‘Next’ button which are located, respectively, in the top-left or bottom-right corners of the Settings page.

Switching to the ‘Parameters’ pane via the settings dropdown menu.

Switching to the ‘Parameters’ pane via the ‘Next’ navigation button.

Complete the fields on the ‘Parameters’ settings pane as follows:

1. ‘Geometry type’: Select the ‘Cylinder’ option to specify cylindrical (i.e. axisymmetric) confinement of the explosive. The other option is ‘Slab’ which would specify two-dimensional, rectangular confinement.
2. ‘Confiner thickness’: This denotes the thickness of the confiner material. Set this to ‘4’.
3. ‘Explosive radius’: This denotes the radius of the explosive material. Set this to ‘10’.
4. ‘Units’: Select the ‘mm’ option to denote that the confiner thickness and explosive radius have been input in millimetres. The other option is ‘inch’.
5. ‘Booster pressure’: This denotes the ratio of the booster pressure to the Chapman-Jouguet pressure and is automatically configured to a sensible value.

Defining the settings on the ‘Parameters’ pane.

To navigate to the ‘Run’ page for this simulation, click on the ‘Continue’ button which is located in the top-right corner of the Settings page. This will save and validate the settings that have been provided and notify you if any errors are identified. If there are no errors, you will be navigated to the simulation ‘Run’ page. The ‘Save’ button to the left of the ‘Continue’ button can be used to save the provided settings at any point.

The ‘Save’ and ‘Continue’ buttons on the Settings page.

Running and monitoring the simulation

‘Run’ page for the simulation.

The ‘Control and ‘Progress’ sections of the simulation ‘Run’ page provide all the functionality required to run and monitor the simulation:

1. Click on the ‘Start’ button to begin the simulation. This will begin the process of starting a cloud compute server (which takes roughly 1.5 minutes) and running the simulation.
   • Note: There is no requirement to remain logged into your account while the simulation runs. Once the simulation is complete, or in the unlikely event that the simulation encounters an error, all compute resources will be automatically terminated so that your account isn’t charged for them.
2. The ‘Stop’ button can be used to terminate a running simulation at any point.
3. The simulation status bar shows useful messages relating to the progress of the simulation. Once the simulation begins running, the wall-time and number of compute credits used are displayed under the status bar and updated in real time as the simulation progresses.
4. One the simulation begins running, the progress bar displays the simulation progress (0-100%) at any point. The simulation time (as opposed to wall-time) is displayed below and updated in real time.
5. The expandable ‘Simulation log’ menu displays the log output produced by the back-end physics code. It may be useful to inspect this in case the simulation terminates with an error.

Visualising the simulation results

Visualising the simulation results.

The ‘Output’ section of the simulation ‘Run’ page can be used to visualise the simulation results:

1. As the simulation runs, a plot of the measured VoD (velocity of detonation) vs time is displayed and updated periodically in the ‘VoD vs time plot’ section.
2. As the simulation runs, a plot of the calculated density contours is displayed and updated periodically in the ‘Density contour plot’ section.
3. The simulation output data can be downloaded for further post-processing by clicking on the ‘Download data’ button.