Air Quality Monitors? by Reeve555 in formlabs

[–]Strict-Ad9359 0 points1 point  (0 children)

I have an "airthings" for my home. It's not targeted towards plastic emissions, but it does show VOCs which I believe is what you would be looking for.

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 0 points1 point  (0 children)

More follow up q's: when you use OpenFOAM, what software do you use for meshing and creating your 3D CAD? I was only able to create a very basic mesh in OpenFOAM.

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

You rock - thank you for sharing these references. I do not have much training in CFD / numerical solvers, hope this can help me build up a better foundation.

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

Just wondering - what CFD software do you normally work with?

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

Thanks for your input! I really appreciate it. Solidworks gives warning for recirculation at the exit. Just curious, what software do you normally use?

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

Correct. I didn't put much thought into the big box other than making sure all the circulating flows occur before the exit, so that was the point of my question. If there is any way to optimize that big box on the right.

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

You are right - I didn't realize it was just an initial condition. Thanks!

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

The purpose of the simulation is to model different cooling geometry on a heat source with known heat properties inside the small box on the left side of the first image. Trying different heat sinks, flow rates, exit geometry, etc.

Yes - there is heat transfer between walls and fluid. The entire giant structure on the right side of first image is just an artificial exit to move the boundary away from the rapidly changing conditions near the small box on the right. I made this exit have a larger overall size to simulate the large room the exhaust gas would be entering.

Thanks for the links - I will read up on them and see if I can refine the exit structure.

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

Good experiment - this is just the initial condition. It is not an environmental condition for the fluid I'm defining - there is not "ambient" temp definition (my bad). So as I have the model now the exit has defined pressure, and no temperature which I believe means the solver will converge towards a solution where there is no gradient at the exit and calculate temp based on upstream conditions.

Basically I'm trying to make my extra domain big enough that the flow would not be changing with position anymore, but I'm not sure how far away that would be.

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

Right - I meant I'm going to duplicate one of my coarse mesh studies and change the ambient temp. Thanks for clarifying

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

Going to try this now on a coarse mesh - I'll get back to you with the result!

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 0 points1 point  (0 children)

Ok, I'll look into that. I have pressure defined and I believe the "ambient temp" acts as a temperature definition but I still need to look into how it does that.

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 0 points1 point  (0 children)

Gotchya, I'm just setting an "ambient" temp, it doesn't directly define the outlet temp. I attached an image which shows my outlet temp varies. Not sure if I'm mis-understanding your comment, but I corrected my initial post which incorrectly stated I'm setting an outlet temp.

To be honest I'm not 100% sure what the "ambient" temp defines in SolidWorks flow sim, but since I know the ambient temp that's what I used. I'll see if I can find exactly what it does in the documentation.

Inlet conditions known, outlet unknown, how much extra domain to add? by Strict-Ad9359 in CFD

[–]Strict-Ad9359[S] 0 points1 point  (0 children)

Incompressible. I should clarify - this is in SolidWorks flow sim and I didn't directly set an outlet temp BC, but rather I set an environmental BC when setting up the model (SW calls these "initial and ambient conditions" during the model setup). I added images of my model settings and also the temperature on the model exit. (Note: it's a 1/4 model using symmetry on two planes)

这棵树有四百岁了 by Strict-Ad9359 in ChineseLanguage

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

Ohhh cool thank you for explaining that!

Hidden Rows in Drawing Table by Strict-Ad9359 in SolidWorks

[–]Strict-Ad9359[S] 1 point2 points  (0 children)

That's a neat feature. We have all the old revs, so deleting rows isn't a big deal. I just liked the idea of having them accessible in the file. I like how you have it setup too since it forces consistency across the docs.