4.2. Coupled Digital Twin Example - Simple Cantilevered Cylinder Half-Submerged in Crossflow¶
Problem files |
4.2.1. Outline¶
Example to demonstrate how to run a coupled OpenSees-OpenFOAM simulation to determine floor loads on a building and then perform an OpenSees simulation of the building assuming uncertainties in the building properties.
The flume is 1 meter wide (from Y=-0.5m to Y=0.5 m), 1 meter tall (Z=0.0m to Z=1.0m), and 4 meters long (X=0.0m to X=4.0m).
The case is initialized with a still water level of 0.25 meters. The velocity at the inlet is given a time history boundary condition (src/VelTime.csv).
This structure is a simple cylinder, with diameter 0.1 meters, located at X=1.5, Y=0.0, Z=0.0. The interface surface file is ‘src/interface.stl’.
The cylinder is represented in OpenSees by a cantilevered beam, with an elastic section, modelled with displacement-action controlled beam elements. The bottom of the cantilevered beam is fixed at Z=0.0.
The constrained node is removed from the coupled solution, by omitting it from the list ‘coupledNodes’ in the OpenSees model file.
The length of the cylinder is 0.5 meters.
The flow around the cylinder is calculated for a given period of time.
Outputs: Results for free surface, velocity, and pressure, as well as interface forces and moments and a cut section of the case at a specified interval.
Overview of case
Probe locations
Inlet Velocity Time History (U(t))
4.2.2. CASE RUN TIME¶
Simulation Time: 1 second on TACC Frontera, 56 processors, 1 node -> Real Time: 1hr, 20 minutes
Submitted Oct 8, 2023 1:14:37 PM Finished Oct 8, 2023 2:34:10 PM
The case can be run for as long as desired, but mind that the longer the case runs, the longer the postprocessing routines will be.
In order to retrieve results from the analysis, the analysis must complete and postprocess the model output files into a VTK format before the end of the allotted submission time.
Provide a large amount of time for the ‘Max Run Time’ field in HydroUQ when submitting a job to ensure the model completes before the time allotted runs out!
Be aware that the smaller the OpenFOAM Outputs and OpenSees Outputs ‘Time Interval’ value is, the longer the post processing of the case will take after analysis has completed, and the larger the results.zip folder will be.
USE CAUTION WHEN REQUESTING OUTPUT! Only ask for what you need, or you will end up will massive amounts of data.
4.2.3. Post Processing¶
Retrieving the results.zip folder from the Tools and Applications Page of Design Safe..
Check if the job has finished. If it has, click ‘More info’.
Find the files by clicking ‘View’.
Move the results.zip to somewhere in My Data/. Use the Extractor tool available on DesignSafe. Unzip the results.zip folder.
OR Download the results.zip folder to your PC and unzip to look at the model results.
Extract the Zip folder either on DesignSafe or on your local machine. You will need Paraview to view the model data.
The results folder should look something like this.
Paraview files have a .PVD extension. Open VTK/Fluid.vtm.series to look at OpenFOAM results. Open OpenSeesOutput.pvd to look at OpenSees results.
OpenSees Displacements And Reactions
OpenFOAM probe and function object output is available in results/postProcessing/.
OpenFOAM output is messy. An example Matlab script is provided in the /src/ directory to post process the OpenFOAM output for this particular case and output. This file can be modified to work for any case. The names of the data folders will need to be changed according to the name of the probe given in HydroUQ.
OpenFOAM Calculated Story Forces
OpenFOAM Calculated Coupled Interface Forces
OpenFOAM Calculated Coupled Interface Moments
OpenFOAM Calculated Pressure Probe Values
OpenFOAM Calculated Velocity Probe Values
OpenFOAM Calculated Free Surface Values
