XY mesh talley data post processing

JimmyG · August 8, 2023, 11:29pm

Currently I am developing a code to read the XY data ( I.e. N-flux vs time) for each mesh point/ nodal point in the model I am simulating and run a convergence code at each point that gives me a rough estimate for at what x value does the y value converge in the simulation. These converged points will then be used as a profile for the simulation and used to iterate between a CFD software. I am currently using abaqus for this and I have a very similar code developed for abaqus. The issues I am having is finding a good way to extract the XY data and run my post processing code on the data to obtain the profile. I am also struggling to find documentation on exporting these data sets to Abaqus ( this may be a totally different type of problem). Another issue I am having, is figuring out a way to have the convergence code running along side the simulation and having my code tell the open MC code when to stop and just output the converged profile. Please let me know if you have any insight into these issues. Thank you so much for your help it is much appreciated.

Shimwell · August 9, 2023, 9:36am

Hi JimmyG

Thanks for posting.

Quite a lot in this question but if we start at the beginning it sounds like you have trouble extracting mesh tally data from a simulation.

Can I ask what type of mesh are you simulating as there are a few in openmc. Can you let us know if it is RegularMesh, UnstructuredMesh or one of the other options

JimmyG · August 9, 2023, 11:06am

Hi Shimwell,
Thank you for your quick reply.
I am looking at using an unstructured mesh, using cubit(trelis now) or Gmsh.

Shimwell · August 9, 2023, 11:55am

There are two examples for unstructured mesh in the notebooks repo.

Just wondering if these help understand the different ways of extracting data from an UnstrucutredMesh mesh

github.com

openmc-dev/openmc-notebooks/blob/main/unstructured-mesh-part-i.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Unstructured Mesh: Introduction\n",
    "\n",
    "In this example we'll look at how to setup and use unstructured mesh tallies in OpenMC. Unstructured meshes are able to provide results over spatial regions of a problem while conforming to a specific geometric features -- something that is often difficult to do using the regular and rectilinear meshes in OpenMC.\n",
    "\n",
    "Here, we'll apply an unstructured mesh tally to the PWR assembly model from the OpenMC examples.\n",
    "\n",
    "**_NOTE: This notebook will not run successfully if OpenMC has not been built with DAGMC or libMesh support enabled._**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],

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github.com

openmc-dev/openmc-notebooks/blob/main/unstructured-mesh-part-ii.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Unstructured Mesh: Tallies with CAD and Point Cloud Visualization\n",
    "\n",
    "In the first notebook on this topic, we looked at how to set up a tally using an unstructured mesh in OpenMC.\n",
    "In this notebook, we will explore using unstructured mesh in conjunction with CAD-based geometry to perform detailed geometry analysis on complex geomerty.\n",
    "\n",
    "_**NOTE: This notebook will not run successfully if OpenMC has not been built with DAGMC support enabled.**_"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [

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JimmyG · August 10, 2023, 12:42am

Yes, this helps a lot thank you! I should be able to obtain the XY data i am looking for now.

JimmyG · September 26, 2023, 10:03pm

Hi Shimwell,
i was able to obtain the XY profile o was looking for but do you know if there is a way to have the convergence code running alongside the simulation and having my code tell the open MC code when to stop and just output the converged profile? or is post processing the only way to obtain a converged profile after the simulation has run? Thank you for your help!

JimmyG · September 26, 2023, 11:39pm

Hi Shimwell,
Do you know if there is also a way to convert a Open MC geometry into a cad based geometry? I need a cad model of the Triga Reactor but am struggling to find one.

Shimwell · September 27, 2023, 9:54am

You could try applying a trigger, here is a link to the docs
https://docs.openmc.org/en/latest/pythonapi/generated/openmc.Trigger.html
I have an example over here

github.com

fusion-energy/neutronics-workshop/blob/main/tasks/task_05_CSG_cell_tally_TBR/2_example_tritium_production_study.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Part 2 - Simulating TBR as a function of Lithium enrichment\n",
    "\n",
    "Lithium isotopes have natural abundances of 7.59% Li6 and 92.41% Li7. However, due to the different (n,Xt) cross sections of the two isotopes it is often beneficial to enrich the Li6 content to increase tritium breeding.\n",
    "\n",
    "This python notebook allows users to make a simple model with a Lithium blanket of controllable enrichment. Simulations are then performed for several different Li6 enrichments and the TBR found."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This first code block a neutronics model for the provided enrichment value, runs the simulation and returns the TBR value obtained."
   ]
  },

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Shimwell · September 27, 2023, 9:58am

Closest thing I know of is MCNPtoCAD

It would be a cool project to make an OpenMC to CAD tool but I’m not aware of anything out there.

You could look at https://openscad.org/ , CadQuery Examples — CadQuery Documentation and GitHub - gumyr/build123d: A python CAD programming library for inspiration of making CAD and some of the CSG syntax is similar in these CAD these codes

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XY mesh talley data post processing

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