topic Re: Flow problem in a cleanroom in CFD Forum

Flow problem in a cleanroom

la206843 — Thu, 22 Jan 2026 13:25:18 GMT

Hi alls,

I am a relatiely new CFD user and I work on air flow inside cleanroom.

My problem is that all my air diffusers are made of an aluminium "boxe" and I wanted to simulate the air flow in the room.

I use a boundary condition for air volume flowrate on the air surface under this aluminium box but there is no flow.

Do you know where are my mistakes and what I should do ?

Any help much apreciated, kind regards.

Re: Flow problem in a cleanroom

Chris.Lechien — Thu, 29 Jan 2026 16:26:32 GMT

Did you define an outlet? The images attached are very small I can not tell how you have set up the simulation.

Re: Flow problem in a cleanroom

la206843 — Sun, 01 Feb 2026 17:11:05 GMT

Hello,

Yes my boundary conditions at the outlet are a pressure at the extraction

Re: Flow problem in a cleanroom

maciej.jaskiernik — Wed, 11 Feb 2026 08:22:06 GMT

Hi @la206843 !

I can take a look at the setup if you are able to send the support file of the simulation.
You can find this file in the parent folder of the simulation.

Please zip it before attaching to message.

Best regards,

Maciej

Re: Flow problem in a cleanroom

oliviagrace4990 — Wed, 18 Feb 2026 09:02:30 GMT

Hi, from your screenshots it looks like the airflow never actually enters the fluid domain because the diffuser faces are still being treated like solid surfaces, so even though you’ve applied a volume flow boundary, the solver isn’t letting air pass through. This usually happens when the outlet face isn’t properly part of the fluid region or gets accidentally blocked by thin solids or overlapping geometry after meshing. It’s worth double-checking that the diffuser surfaces are assigned to the air/fluid domain, trying a simple velocity inlet first to verify flow, and inspecting the mesh around the openings closely. A similar issue and potential ideas are discussed here on the Autodesk CFD forum: https://forums.autodesk.com/t5/cfd-forum/no-airflow-from-inlet-boundary/td-p/8145672. For a related practical reference on airflow and environmental monitoring hardware, you can also look at this PCBWay project about an ESP32-based air quality monitoring system: https://www.pcbway.com/project/shareproject/AirSENSE_Mobile_ESP32_Based_Portable_Air_Quality_Monitoring_System_2dd98a43.html. In most cases, fixing the fluid/solid interface and remeshing solves the no flow problem.