Attach a vent to a wall

[Swissi]

Hi everyone,

After summer vacation I'm coming with a new question : I have to attach vent to walls, but I've always the same error : "VENT XX must be attached to soli obstruction".

I don't know how to attach correctly vents to walls. Can you help me? 

[Swissi]

No One can help me?

[Charlie Thornton]

Strange. I thought I responded a few days ago. Maybe I subsequently deleted the response during spam moderation. I'm glad you bumped the post.

Vents can only be attached to the domain boundary or thick obstructions. When I say "thick" I mean they must be at least one grid cell thick. Obstructions that are either 2D or became 2D because of the grid resolution cannot hold a vent. There may still be an exception for porous "fan" vents, but for the most part the OBST needs to have some depth.

Most commonly, people get the "...must be attached to a solid obstruction" error when their mesh resolution is bigger than their obstructions and the obstructions are subsequently flattened by FDS - quietly making the obstructions unsuitable for hosting a VENT. If this is your problem, the solution is to either use a finer mesh or edit the geometry to be fat enough to survive the flattening step.