I’ve imported a model from SketchUp (as stl, no problem).
In Sketchup, this is a hollow cube, in Simscale’s CAD tool it is two solids. Choosing a seed face for an internal flow volume gives (obviously) an error (face needs to be next to empty space).
How can I fix this?
Eventually I want to simulate a (closed) indoor environment with fans inside to see how the air moves around objects and walls.
On that note: is possible (and how) to place a rectangular volume, which on one face pushes air with a certain volumetric flow rate and on another face of the same object takes in that air?
Two different solids are forming probably due to automatic sewing operation toggled on while importing your geometry. When this is the case, you don’t always have to use flow volume extraction operation. The flow region may already be represented by existing parts in your geometry.
Here we can have two scenarios. In case you are only interested in a flow/air simulation in the hollow region, you can go ahaed and Delete the bigger solid. Remaining smaller cube will be representing your flow region, and will be bounded by the external faces. These external faces can be assigned with several type of boundary conditions to represent different environments. Here the Convective Heat Transfer simulations would be the best choice.
In case you are interested in the heat transfer in the solid parts surrounding the hollow region along with flow movement inside, then the correct simulation type would be Conjugate Heat Transfer. Solid and fluid regions should be represented by separate solid parts. In order to achieve that, Boolen/Subtract operation in the CAD mode should do the trick. (please remember to “Keep Tools” to serve your purpose correctly) After this operation is completed, outer part will be representing solids while inner part will be representing fluids. Materials to these parts should be assigned during the simulation set up, same as any other simulation type.
Thank you for the quick help!
I guess that was it - it was already created.
To follow up on your suggestion: why do you think a convective heat transfer simulation is the best choice? I would have assumed ‘imcompressible’ is the way to go. I’m really only interested in the air movement.
I added a small volume (serving as the velocity inlet / pressure outlet) and substracted it from the fluid volume in the CAD tool and assigned velocities to (in and out) to two faces. Simscale see two fluid volumes…
As for the boundary conditions, is it correct to assigned a face as velocity inlet and a face as pressure outlet (I chose 1 atm)? In my mind this reflects the behavior of a closed loop with a body that takes in air on one side and pushes it out on another.
I suggested the convective heat transfer, because I assumed you would have some heat sources inside the room as well such as: PC, humans, etc. When you have such heat sources, density of the air becomes important, and buoyancy effects start to take place. If you don’t have such sources and you are only interested in the air pattern, you can continue with Incompressible simulation type as you suggested.
In order to form inlet and outlet boundaries, adding a small volume and using it’s faces as boundaries makes sense. However, Incompressible simulation type only requires one part that will represent the flow region. Unless other parts in your geometry assigned with some of the advanced concepts, you should again use Boolen/Subtract operation to remove the small volume.
Regarding your latest question, velocity inlet - pressure outlet is indeed well known to provide stable results so you can continue with this pairing. Just a side note, the pressure input in pressure outlet is defined as gauge pressure so it should be defined as 0 atm/Pa to represent the atmospheric exit.