A Monte-Carlo Simulator package developed at CERN

Bookmarks to different parts (detailed in the bullet points below) are in the video description:

If you're new to these Monte Carlo tools, this presentation is a good overview of the special physics at very low pressures, how it's related to Monte Carlo simulations, and how Molflow actually works.

- Short explanation of the high vacuum physics
- The Monte Carlo method
- History of Molflow and Synrad
- Typical Molflow workflow

The interface is your first encounter with Molflow, this video shows the basic controls and also some tips and tricks.

- Loading a simple pipe
- Mouse commands (zoom, pan, rotate)
- Default views and area zoom
- View options, view parameters, light options
- Additional parts of the interface, global settings, white background
- Screenshot tool
- Toggling coordinate axes
- Advanced: 4 split views

Highly recommended to watch: shows the different techniques to select facets, then memorize them as groups. Mastering these will save you a lot of time later.

- Creating a 100-sided pipe
- Select by clicking on geometry
- Cycle through overlapping facets
- Select by facet number in list
- Options for selection display in volume view
- Select multiple facets
- Selection box
- Multi-select from facet list
- Add overlapping facets to selection
- Memorizing selections
- Recalling and combining selections
- Smart select tool

Tips and tricks useful for geometry editing and large geometries where using traditional techniques are cumbersome.

- Select by number (facet id)
- Invert selection
- Select vertices
- Select in circle
- Move selection box/circle anchor
- TAB to switch facet/vertex modes
- Difference between add/remove logic
- Restrict selectable facets by Caps Lock

As opposed to importing a geometry from an external editor, you can now create your geometry from scratch. This tutorial walks you through the steps to assemble a basic vacuum system, consisting of two pumping ports and a variable diameter pipe.

Result geometry: ansys_geometry.zip

- Starting with an empty geometry
- Create a circle and extrude it to a pipe
- Create a larger diameter circle at end of pipe
- Create difference of two circles
- Adding vertical pumping ports
- Rotating a circle (using an axis)
- Rotating a circle (using 2 vertices)
- Move a circle by fixed offset
- Move a circle up to an existing facet
- Mirroring a pipe to a plane
- Fixing a 0-area facet with the Collapse command
- Building T intersections between pipes
- Fixing the T intersection by scaling down vertical pipe
- Clear isolated vertices

Finishing the example from the previous video by adding physics and comparing the pressure result with the published paper

Source geometry: ansys_geometry.zip

Solved exercise: ansys_with_physics.zip (with symmetry: symmetric.zip)

- Adding outgassing
- Adding the pumps
- Setting up textures
- Setting up profiles
- Advanced: taking advantage of symmetry

An example of a vacuum simulation of a realistic geometry. You can get the source files from this tutorial's page.

- Importing the STL file to Molflow
- Adding outgassing
- Adding pumps
- Starting the simulation
- Adding textures (pressure color maps)
- Playing with mesh resolution
- Manual texture color scaling
- Single counter facet instead of texturing all
- Measuring distances in Molflow
- Setting counter facet parameters and texture
- Visualization techniques
- Adding a profile (pressure along a direction)
- Adding a new profile facet by scaling
- Exporting profiles and textures
- Splitting the geometry horizontally

**Conductance, part 1:** theory and a simple (round pipe) example:

- Theory and formulae for conductance
- Simple round pipe example + analytic solutions
- Constructing the geometry, adding sticking and outgassing
- Using formulas to determine transmission probability
- Monte Carlo vs analytic results
- Calculating conductance from transmission probability

**Conductance, part 2**: real-life CAD example

- Importing the geometry, collapsing and rotating
- Setting up pumping, desorption and sampling planes
- Creating plugs
- Starting simulation, extracting results
- Using formulas to get average pressure
- Verifying results: changing the pumping speed
- Detailed results after more simulation time

Files:

CAD000567144.stl (Geometry)

test_rf.zip (Solution)

Additional tools to get deep insight into the behavior of your system

- Angular profiles
- Direction vector textures
- Velocity profile
- Histograms
- Particle logger

Vacuum systems with different facet temperatures

- Governing equations
- Accomodation factor
- Thermal creep example

Simulating a vacuum system with a large pressure difference in multiple steps

Recording an angular distribution and generating gas with it

Gaining ray-tracing speed from sectioning the geometry to smaller parts

Advanced tools taking advantage of symmetries in the system and similar structures

- Symmetry plane
- Periodic systems and teleports
- Inverse teleports

- Acoustic delay line example
- Timewise plotter
- Pressure evolution plotter
- Time-dependent physical parameters

Source geometry: adl1.stl

Solved result: adl_timedep_outg.zip

- Radioactive decay
- Surface sojourn time

Theme by Danetsoft and Danang Probo Sayekti inspired by Maksimer