# PLEASE HELP! Geometry solid body problem when creating external flow volume **URL:** \ **Category:** CAD Mode Support\ **Created:** [January 25, 2025, 10:12am UTC](https://www.simscale.com/forum/t/please-help-geometry-solid-body-problem-when-creating-external-flow-volume/99714 "2025-01-25T10:12:33Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![harryfeng](https://www.simscale.com/forum/letter_avatar/harryfeng/32/5_5575768a8748004e209b776fc1b2916d.png) [@harryfeng](https://www.simscale.com/forum/u/harryfeng)\ **Post date:** [January 24, 2025, 3:13pm UTC](https://www.simscale.com/forum/t/please-help-geometry-solid-body-problem-when-creating-external-flow-volume/99714/1 "2025-01-24T15:13:07Z")
> **[SimScale Login](https://www.simscale.com/workbench/?pid=8139270420282846604&dcs=2801cb7a-471d-4c0c-8f3c-012b0b46a3d8)** > > Log in to your SimScale account. SimScale makes high-fidelity engineering simulation technically and economically accessible. At any scale. In the cloud. pls help with the faults. i think most of it is coming from the tires, but ive no idea what to do ---
**Author:** ![harryfeng](https://www.simscale.com/forum/letter_avatar/harryfeng/32/5_5575768a8748004e209b776fc1b2916d.png) [@harryfeng](https://www.simscale.com/forum/u/harryfeng)\ **Post date:** [January 25, 2025, 10:12am UTC](https://www.simscale.com/forum/t/please-help-geometry-solid-body-problem-when-creating-external-flow-volume/99714/2 "2025-01-25T10:12:33Z")
> **[SimScale Login](https://www.simscale.com/workbench/?pid=5126915267921136080&dcs=38e5ae6d-4960-472c-855e-4cb3df24c91b)** > > Log in to your SimScale account. SimScale makes high-fidelity engineering simulation technically and economically accessible. At any scale. In the cloud. The geometry is already 100% watertight?? What else do I need to do? This doesn’t make any sense it’s literally one solid object (apart from the rear wing and drive shafts and tires). I’ve also tried converting to solid in freeCAD but it still didn’t work, this is not intuitive at all. ---
**Author:** ![harryfeng](https://www.simscale.com/forum/letter_avatar/harryfeng/32/5_5575768a8748004e209b776fc1b2916d.png) [@harryfeng](https://www.simscale.com/forum/u/harryfeng)\ **Post date:** [January 25, 2025, 11:09am UTC](https://www.simscale.com/forum/t/please-help-geometry-solid-body-problem-when-creating-external-flow-volume/99714/3 "2025-01-25T11:09:09Z")
i tried using the wrap method to create a simulation-ready object but it keeps CLOSING OFF the tunnel inside the car. Everything else works fine. Why does it close off the tunnel??? I’ve already tried selecting “allow tunnel”. ---
**Author:** ![nelta](https://www.simscale.com/forum/letter_avatar/nelta/32/5_5575768a8748004e209b776fc1b2916d.png) [@nelta](https://www.simscale.com/forum/u/nelta)\ **Post date:** [January 26, 2025, 3:09am UTC](https://www.simscale.com/forum/t/please-help-geometry-solid-body-problem-when-creating-external-flow-volume/99714/4 "2025-01-26T03:09:16Z")
Perhaps, try to import your model in a different file format. STL files are not recommended (unless for LBM or PWC simulations). STL files contain only faceted data and are thus difficult to convert to a solid body. ---
**Author:** ![harryfeng](https://www.simscale.com/forum/letter_avatar/harryfeng/32/5_5575768a8748004e209b776fc1b2916d.png) [@harryfeng](https://www.simscale.com/forum/u/harryfeng)\ **Post date:** [January 26, 2025, 3:43am UTC](https://www.simscale.com/forum/t/please-help-geometry-solid-body-problem-when-creating-external-flow-volume/99714/5 "2025-01-26T03:43:13Z")
What other formats do u recommend? step. file doesnt work either I’ve tried. It’s frustrating because I know 100% that it is a watertight geometry (checked in both in Blender and freeCAD). ---
**Author:** ![nelta](https://www.simscale.com/forum/letter_avatar/nelta/32/5_5575768a8748004e209b776fc1b2916d.png) [@nelta](https://www.simscale.com/forum/u/nelta)\ **Post date:** [January 26, 2025, 4:14am UTC](https://www.simscale.com/forum/t/please-help-geometry-solid-body-problem-when-creating-external-flow-volume/99714/6 "2025-01-26T04:14:03Z")
The suggestion would be to try STEP or Parasolid. > [@Project composed of sheets and not solids](https://www.simscale.com/forum/t/project-composed-of-sheets-and-not-solids/92714/6): > > Have a look here: [https://www.simscale.com/workbench/?pid=3616066946687027260&mi=geometry%3A4&mt=GEOMETRY](https://www.simscale.com/workbench/?pid=3616066946687027260&mi=geometry%3A4&mt=GEOMETRY) This should work slight_smile You can simply download the geometry and use it. ---
**Author:** ![harryfeng](https://www.simscale.com/forum/letter_avatar/harryfeng/32/5_5575768a8748004e209b776fc1b2916d.png) [@harryfeng](https://www.simscale.com/forum/u/harryfeng)\ **Post date:** [January 26, 2025, 2:55pm UTC](https://www.simscale.com/forum/t/please-help-geometry-solid-body-problem-when-creating-external-flow-volume/99714/7 "2025-01-26T14:55:45Z")
Ive figured it out. I used freeCAD to convert to step.