# \#molflow **URL:** https://molflow-forum.web.cern.ch/tag/molflow/2.md [Latest](https://molflow-forum.web.cern.ch/latest.md) · [Categories](https://molflow-forum.web.cern.ch/categories.md) · [Tags](https://molflow-forum.web.cern.ch/tags.md) --- ## [Beginner at Molflow. Understanding Outgassing data, and how to get ultimate pressure](https://molflow-forum.web.cern.ch/t/beginner-at-molflow-understanding-outgassing-data-and-how-to-get-ultimate-pressure/773)
**Author:** [@Rford](https://molflow-forum.web.cern.ch/u/Rford)\ **Replies:** 2\ **Last updated:** [October 1, 2026, 8:31pm UTC](https://molflow-forum.web.cern.ch/t/beginner-at-molflow-understanding-outgassing-data-and-how-to-get-ultimate-pressure/773 "2026-10-01T20:31:55Z")
Hello, I am trying to use Molflow to calculate the ultimate pressure of a future chamber. While also using molflow to match the data from an existing chamber as proof of me doing it right. I don’t really know what outg… --- ## ["Copy All" popup doesn't copy when UI Scale \<\> 1](https://molflow-forum.web.cern.ch/t/copy-all-popup-doesnt-copy-when-ui-scale-1/768)
**Author:** [@alan](https://molflow-forum.web.cern.ch/u/alan)\ **Replies:** 2\ **Last updated:** [August 6, 2026, 7:15am UTC](https://molflow-forum.web.cern.ch/t/copy-all-popup-doesnt-copy-when-ui-scale-1/768 "2026-08-06T07:15:46Z")
I recently had to set the UI scale to less than 1 because my memorized selection list got too long. However, when the UI scaling is anything other than 1 the Copy All popup on a right mouse click will not copy the data f… --- ## [Cryostat conductance calculation](https://molflow-forum.web.cern.ch/t/cryostat-conductance-calculation/766)
**Author:** [@susiri](https://molflow-forum.web.cern.ch/u/susiri)\ **Replies:** 2\ **Last updated:** [June 25, 2026, 5:04am UTC](https://molflow-forum.web.cern.ch/t/cryostat-conductance-calculation/766 "2026-06-25T05:04:41Z")
Hi All, I’m a bit new to this molflow+ software. I need to develop a model to calculate the conductance of pipes and connections leading to the pump from the cryostat. Cryostat top flange has a diameter around 400 mm. Cr… --- ## [Use molflow 2.11.1 benchmarking :base pressure higher than Paper](https://molflow-forum.web.cern.ch/t/use-molflow-2-11-1-benchmarking-base-pressure-higher-than-paper/764)
**Author:** [@cainiao233](https://molflow-forum.web.cern.ch/u/cainiao233)\ **Replies:** 7\ **Last updated:** [June 22, 2026, 12:06pm UTC](https://molflow-forum.web.cern.ch/t/use-molflow-2-11-1-benchmarking-base-pressure-higher-than-paper/764 "2026-06-22T12:06:43Z")
Use molflow 2.11.1 benchmarking,base pressure is higher than paper。Can the Y-axis sub-scale be adjusted? --- ## [Leak issues](https://molflow-forum.web.cern.ch/t/leak-issues/763)
**Author:** [@Manas](https://molflow-forum.web.cern.ch/u/Manas)\ **Replies:** 2\ **Last updated:** [June 16, 2026, 9:17am UTC](https://molflow-forum.web.cern.ch/t/leak-issues/763 "2026-06-16T09:17:48Z")
Dear Marton, I am relatively new to Molflow. I am trying to do the vacuum simulation for a beam line. The STL file is created using solidworks. However, I am getting leaks in and around few facets of the imported … --- ## [Physical inaccuracy: 0 reflections for long time simulation with short sojourn times when T variable](https://molflow-forum.web.cern.ch/t/physical-inaccuracy-0-reflections-for-long-time-simulation-with-short-sojourn-times-when-t-variable/759)
**Author:** [@AlexLaroche](https://molflow-forum.web.cern.ch/u/AlexLaroche)\ **Replies:** 3\ **Last updated:** [May 27, 2026, 3:44pm UTC](https://molflow-forum.web.cern.ch/t/physical-inaccuracy-0-reflections-for-long-time-simulation-with-short-sojourn-times-when-t-variable/759 "2026-05-27T15:44:12Z")
Molflow version: Windows binary v2.11.0, v2.10.2 When sojourn time is used on a facet, and the facet’s temperature is set to a parameter, the reflections from the surface reduce to 0 when the probability of sojourn time… --- ## [V2.11.0 Windows: "Select Init. Particles" opens "Create junction" tool](https://molflow-forum.web.cern.ch/t/v2-11-0-windows-select-init-particles-opens-create-junction-tool/758)
**Author:** [@AlexLaroche](https://molflow-forum.web.cern.ch/u/AlexLaroche)\ **Replies:** 1\ **Last updated:** [May 27, 2026, 3:14pm UTC](https://molflow-forum.web.cern.ch/t/v2-11-0-windows-select-init-particles-opens-create-junction-tool/758 "2026-05-27T15:14:35Z")
Windows binary v2.11.0. Menu: Selection-\>“Select Init. Particles” opens the Facet-\>“create elbowT/junction..” tool. --- ## [Texture storage of sum\_v\_ort](https://molflow-forum.web.cern.ch/t/texture-storage-of-sum-v-ort/743)
**Author:** [@thofell](https://molflow-forum.web.cern.ch/u/thofell)\ **Replies:** 1\ **Last updated:** [February 10, 2026, 1:30pm UTC](https://molflow-forum.web.cern.ch/t/texture-storage-of-sum-v-ort/743 "2026-02-10T13:30:21Z")
Hello, first of all it is not really a bug, but it took me some time to figure it out. I was trying to recalculate the pressure from the stored texture data in the XML-file. The paramter “sum\_v\_ort” is stored as sum\_v\_… --- ## [Staged pumping setup for 88" Cyclotron](https://molflow-forum.web.cern.ch/t/staged-pumping-setup-for-88-cyclotron/742)
**Author:** [@dmkonyndyk](https://molflow-forum.web.cern.ch/u/dmkonyndyk)\ **Replies:** 3\ **Last updated:** [January 16, 2026, 9:31am UTC](https://molflow-forum.web.cern.ch/t/staged-pumping-setup-for-88-cyclotron/742 "2026-01-16T09:31:36Z")
Hello everyone, thanks for having me. I am setting up a simulation for a differential pumping section, which is a series of four crosses with apertures in between. Each cross has a pump, and I have an inlet where I have … --- ## [Mean Free Path Variation in Different Regions](https://molflow-forum.web.cern.ch/t/mean-free-path-variation-in-different-regions/741)
**Author:** [@100013312](https://molflow-forum.web.cern.ch/u/100013312)\ **Replies:** 1\ **Last updated:** [December 12, 2025, 7:52am UTC](https://molflow-forum.web.cern.ch/t/mean-free-path-variation-in-different-regions/741 "2025-12-12T07:52:34Z")
Subject: Mean Free Path Variation in Different Regions Hi all, I have a question about how Molflow handles mean free path. Since local pressure differs in various regions of my geometry, the MFP should vary as well. H… --- ## [Impingement rate and particle density](https://molflow-forum.web.cern.ch/t/impingement-rate-and-particle-density/447)
**Author:** [@59787439](https://molflow-forum.web.cern.ch/u/59787439)\ **Replies:** 3\ **Last updated:** [December 10, 2025, 7:24am UTC](https://molflow-forum.web.cern.ch/t/impingement-rate-and-particle-density/447 "2025-12-10T07:24:56Z")
Hi, I would like to know the meaning of “1” in the Impingement rate and particle density in the figure. Does the “1” mean the number of particles if I understand correctly? Best, Lee --- ## [Subject: Clarification on how Molflow relates density, pressure, and impingement rate](https://molflow-forum.web.cern.ch/t/subject-clarification-on-how-molflow-relates-density-pressure-and-impingement-rate/738)
**Author:** [@100013312](https://molflow-forum.web.cern.ch/u/100013312)\ **Replies:** 15\ **Last updated:** [December 8, 2025, 12:37pm UTC](https://molflow-forum.web.cern.ch/t/subject-clarification-on-how-molflow-relates-density-pressure-and-impingement-rate/738 "2025-12-08T12:37:40Z")
Hello everyone, I am trying to understand how the different physical quantities in Molflow are interconnected—specifically density, pressure, impingement rate, and speed. I am finding inconsistencies that I cannot fully… --- ## [Recorded angle maps desorption](https://molflow-forum.web.cern.ch/t/recorded-angle-maps-desorption/737)
**Author:** [@Romain\_RICHARD](https://molflow-forum.web.cern.ch/u/Romain_RICHARD)\ **Replies:** 4\ **Last updated:** [December 5, 2025, 3:15pm UTC](https://molflow-forum.web.cern.ch/t/recorded-angle-maps-desorption/737 "2025-12-05T15:15:52Z")
Hello, I record an angle map from a sub model then create a desorbing facet in my principal model using the “Recorded” feature for Desorption. It seems to work just fine except in the theta = 0 (normal) direction where… --- ## [Only count a portion of the molecules](https://molflow-forum.web.cern.ch/t/only-count-a-portion-of-the-molecules/733)
**Author:** [@112768120733363847496](https://molflow-forum.web.cern.ch/u/112768120733363847496)\ **Replies:** 1\ **Last updated:** [October 9, 2025, 10:35am UTC](https://molflow-forum.web.cern.ch/t/only-count-a-portion-of-the-molecules/733 "2025-10-09T10:35:34Z")
Hello Molflow’s Creator, My model is just a simple pipe, the two end faces of the pipe are facet A and facet B. A desorption is set on facet A, desortion type and reflection type are uniform. The sticking factor of face… --- ## [Discrepancy between Molflow+ simulation and Hagen-Poiseuille equation for pressure drop](https://molflow-forum.web.cern.ch/t/discrepancy-between-molflow-simulation-and-hagen-poiseuille-equation-for-pressure-drop/726)
**Author:** [@TES](https://molflow-forum.web.cern.ch/u/TES)\ **Replies:** 6\ **Last updated:** [September 26, 2025, 7:42am UTC](https://molflow-forum.web.cern.ch/t/discrepancy-between-molflow-simulation-and-hagen-poiseuille-equation-for-pressure-drop/726 "2025-09-26T07:42:52Z")
Hi I’m a new user of Molflow+ and I’m encountering a discrepancy between the pressure drop calculated from my simulation and the pressure drop calculated using the Hagen-Poiseuille equation. I’m trying to understand why… --- ## [Molflow launch error](https://molflow-forum.web.cern.ch/t/molflow-launch-error/699)
**Author:** [@Sourav](https://molflow-forum.web.cern.ch/u/Sourav)\ **Replies:** 6\ **Last updated:** [September 10, 2025, 2:22pm UTC](https://molflow-forum.web.cern.ch/t/molflow-launch-error/699 "2025-09-10T14:22:53Z")
Hello, I have installed Molflow v2.9.27 on windows 11. However, when I launch the program, it opens a window and then crashes. I have attached the screenshot below. I have tried deleting the four files mentioned on the … --- ## [Mean flight time of molecule in a specific part of model](https://molflow-forum.web.cern.ch/t/mean-flight-time-of-molecule-in-a-specific-part-of-model/722)
**Author:** [@112768120733363847496](https://molflow-forum.web.cern.ch/u/112768120733363847496)\ **Replies:** 1\ **Last updated:** [September 10, 2025, 10:01am UTC](https://molflow-forum.web.cern.ch/t/mean-flight-time-of-molecule-in-a-specific-part-of-model/722 "2025-09-10T10:01:03Z")
Hello Molflow’s Creator, I encountered a problem while performing simulations. My model is composed of circular pipes with varying diameters. I have learned that I can eatimate the mean flight time of particles from gen… --- ## [VacuumCost crashing out with data conversion error](https://molflow-forum.web.cern.ch/t/vacuumcost-crashing-out-with-data-conversion-error/715)
**Author:** [@guest\_matthew.cox](https://molflow-forum.web.cern.ch/u/guest_matthew.cox)\ **Replies:** 9\ **Last updated:** [August 7, 2025, 9:02am UTC](https://molflow-forum.web.cern.ch/t/vacuumcost-crashing-out-with-data-conversion-error/715 "2025-08-07T09:02:49Z")
Hi all I’m having trouble running VacuumCost to simulate beam conditioning behaviour at fixed timesteps. I’m not sure if it is a problem with my Molflow model or the version of Molflow GUI (2.9.28), MolflowCli (2.9.28) … --- ## [Application crashing when "Select by Facet Number..." is clicked](https://molflow-forum.web.cern.ch/t/application-crashing-when-select-by-facet-number-is-clicked/714)
**Author:** [@108942885747285572606](https://molflow-forum.web.cern.ch/u/108942885747285572606)\ **Replies:** 2\ **Last updated:** [August 6, 2025, 7:04pm UTC](https://molflow-forum.web.cern.ch/t/application-crashing-when-select-by-facet-number-is-clicked/714 "2025-08-06T19:04:40Z")
I am running MolFlow 2.9.28 on a windows machine and the application crashes when I click “Select by Facet Number…”. I have tried this with a fresh instance of MolFlow (with no geometry) as well as with a geometry insert… --- ## [Conductance calculation short tube with area restriction](https://molflow-forum.web.cern.ch/t/conductance-calculation-short-tube-with-area-restriction/712)
**Author:** [@vaststefano](https://molflow-forum.web.cern.ch/u/vaststefano)\ **Replies:** 5\ **Last updated:** [July 28, 2025, 7:09am UTC](https://molflow-forum.web.cern.ch/t/conductance-calculation-short-tube-with-area-restriction/712 "2025-07-28T07:09:24Z")
Hello to everyone, I have a question about conductance calculation for a very short tube (h = 2mm). The gas flows into two concentric cylinders and it has a diameter restriction, while the outer diameter is constant. I… --- ## [Pumping manifold conductance](https://molflow-forum.web.cern.ch/t/pumping-manifold-conductance/708)
**Author:** [@e-nico911](https://molflow-forum.web.cern.ch/u/e-nico911)\ **Replies:** 4\ **Last updated:** [July 28, 2025, 6:05am UTC](https://molflow-forum.web.cern.ch/t/pumping-manifold-conductance/708 "2025-07-28T06:05:11Z")
Hi, last winter I started to study vacuum technology and now I’m working on to study a simple vacuum cavity (for RF test) and to design an appropriate pumping interface. I designed a simple manifold made by two tee DN … --- ## [Angular Distribution in MolFlowCLI](https://molflow-forum.web.cern.ch/t/angular-distribution-in-molflowcli/711)
**Author:** [@phips](https://molflow-forum.web.cern.ch/u/phips)\ **Replies:** 5\ **Last updated:** [July 24, 2025, 8:57am UTC](https://molflow-forum.web.cern.ch/t/angular-distribution-in-molflowcli/711 "2025-07-24T08:57:57Z")
Hi Molflow team, is there a way to export an angular distribution when using MolflowCLI on an external server, since it can´t be saved into the file.? Am I doing something wrong or is this by design? Molflow version 2.… --- ## [Can moflowcli or other method be used to scan the pumping speed parameter?](https://molflow-forum.web.cern.ch/t/can-moflowcli-or-other-method-be-used-to-scan-the-pumping-speed-parameter/701)
**Author:** [@sammylvp](https://molflow-forum.web.cern.ch/u/sammylvp)\ **Replies:** 1\ **Last updated:** [June 10, 2025, 9:26am UTC](https://molflow-forum.web.cern.ch/t/can-moflowcli-or-other-method-be-used-to-scan-the-pumping-speed-parameter/701 "2025-06-10T09:26:39Z")
I want to model a UHV chamber system and find the best condition for the vacuum pumps, especially the right pumping speed, so I want to be able to scan the pumping speed parameter. I understand molflowCLI can scan parame… --- ## [How do I export detailed facet physics in a mesh/profile?](https://molflow-forum.web.cern.ch/t/how-do-i-export-detailed-facet-physics-in-a-mesh-profile/627)
**Author:** [@103865651561993978278](https://molflow-forum.web.cern.ch/u/103865651561993978278)\ **Replies:** 9\ **Last updated:** [June 10, 2025, 8:48am UTC](https://molflow-forum.web.cern.ch/t/how-do-i-export-detailed-facet-physics-in-a-mesh-profile/627 "2025-06-10T08:48:27Z")
Hi All, I am moving to the bash to run multiple experiments as I need different outgassing tests. From these experiments I want to extract all of the data/profiles along a specified facet (no issues if it is only 100 p… --- ## [The issue of force calculation when setting a moving part](https://molflow-forum.web.cern.ch/t/the-issue-of-force-calculation-when-setting-a-moving-part/696)
**Author:** [@wangpengfy](https://molflow-forum.web.cern.ch/u/wangpengfy)\ **Replies:** 3\ **Last updated:** [March 18, 2025, 8:58am UTC](https://molflow-forum.web.cern.ch/t/the-issue-of-force-calculation-when-setting-a-moving-part/696 "2025-03-18T08:58:17Z")
Hello marton, I want to simulate the molecular impact force on the windward surface of a spacecraft in orbit. Below is my model. The small rectangular box represents the spacecraft, and the larger one represents spa… --- ## [How to simulate and track more than two gases](https://molflow-forum.web.cern.ch/t/how-to-simulate-and-track-more-than-two-gases/692)
**Author:** [@113263725560786637381](https://molflow-forum.web.cern.ch/u/113263725560786637381)\ **Replies:** 1\ **Last updated:** [February 27, 2025, 10:47am UTC](https://molflow-forum.web.cern.ch/t/how-to-simulate-and-track-more-than-two-gases/692 "2025-02-27T10:47:41Z")
Hi everyone Is it possible to simulate the collision and paths of more than two gas molecules using Molflow? For example, different intake pipes are used to supply nitrogen and hydrogen respectively, and the adsorption… --- ## [Validity of Molflow simulations](https://molflow-forum.web.cern.ch/t/validity-of-molflow-simulations/641)
**Author:** [@Cris87](https://molflow-forum.web.cern.ch/u/Cris87)\ **Replies:** 11\ **Last updated:** [February 21, 2025, 7:41am UTC](https://molflow-forum.web.cern.ch/t/validity-of-molflow-simulations/641 "2025-02-21T07:41:44Z")
Hello all, Although Molflow+ is an attractive software for vacuum system simulations, I am concerned about the validity of the outputs. I tried to evaluate the conductance between the main chamber and the pumping statio… --- ## [Molflow.exe and atio6axx.dll error](https://molflow-forum.web.cern.ch/t/molflow-exe-and-atio6axx-dll-error/686)
**Author:** [@112221710736148264031](https://molflow-forum.web.cern.ch/u/112221710736148264031)\ **Replies:** 3\ **Last updated:** [February 17, 2025, 2:53pm UTC](https://molflow-forum.web.cern.ch/t/molflow-exe-and-atio6axx-dll-error/686 "2025-02-17T14:53:28Z")
I am an engineer learning to use Molflow for thermal evaporation simulation. I am currently using Molflow version 2.9.27, and I am experiencing the following error. I would like to ask for advice on how to solve this iss… --- ## [Please enable molflowCLI to export all moments' physical quantities in time-dependent simulation](https://molflow-forum.web.cern.ch/t/please-enable-molflowcli-to-export-all-moments-physical-quantities-in-time-dependent-simulation/678)
**Author:** [@wangpengfy](https://molflow-forum.web.cern.ch/u/wangpengfy)\ **Replies:** 1\ **Last updated:** [January 13, 2025, 9:57am UTC](https://molflow-forum.web.cern.ch/t/please-enable-molflowcli-to-export-all-moments-physical-quantities-in-time-dependent-simulation/678 "2025-01-13T09:57:46Z")
Hello Marton, Recently, I use VacuumCOST to simulate the pressure changes inside a vacuum chamber. My model is divided into two stages. In the first stage, the model is closed with no pumps, and NEG is used to maintain … --- ## [How to calculate a sticking facet's throughput?](https://molflow-forum.web.cern.ch/t/how-to-calculate-a-sticking-facets-throughput/676)
**Author:** [@wangpengfy](https://molflow-forum.web.cern.ch/u/wangpengfy)\ **Replies:** 7\ **Last updated:** [January 10, 2025, 11:01am UTC](https://molflow-forum.web.cern.ch/t/how-to-calculate-a-sticking-facets-throughput/676 "2025-01-10T11:01:28Z")
Hello Marton, I have constructed a pipe with a radius of 0.25 cm and a length of 20 cm. The left end is set with a constant outgassing rate of 2.28e-8 mbarL/s, while the right end is a pump that pump speed determined b… [Next page](https://molflow-forum.web.cern.ch/tag/molflow/2.md?match_all_tags=true&page=1&tags%5B%5D=molflow)