Natural Ventilation around the building gravity direction?

[rucio]

Hello, 

I am trying to simulate the air passing through the building.

I follow the tutorial in "natural ventilation" article, then set up the parameters as following:

Materials:

Air materials to domain environment, variable. 

Concrete materials to whole building.

Boundary condition:

inlet: air speed and temperature,

outlet: pressure =0

Slip to left, right and top

Solve:

Heat transfer= On

Gravity method =earth

Gravity direction =0,0,-1

My question is

1. for simulating buoyancy effect and natural ventilation, how do I set up gravity direction?

2. Are there any parameter that I missed in this simulation?

thank you!

[Jon.Wilde]

Nice work, on the face of it, it looks like everything is set right 🙂

You already have gravity on, just be sure it is acting downwards and you are all set.

One thing to check might be the mesh quality (see if refining it effects the results at all). Otherwise, very cool indeed!

[rucio]

Thanks for the compliment. what I did is following some tutorials.

I want to ask what is different between gravity (0,0,0) and (0,0,-1)?

In the natural ventilation case, should we always set gravity direction to (0,0,-1)?

thank you

[Jon.Wilde]

Sure thing, its nice to see 🙂

0,0,0 is no gravity, if you set a value of 1 in any direction then you will get 'earth' gravity in that direction - exactly as you have 😉

[rucio]

Thanks for the explanation.

After a successful run of simulation, I hit the solve button again.

But this time the run did not go well as the first time.

In the end of simulation, it confronted unexpectedly stop, the divergence issues.

I don't know why the error happened because I didn't change any parameter from the model of first attempt.

I am attaching the file here, hope we can better understand what is going wrong.

Thank you!!

[rucio]

Hello, 

I manage to solve the problem by setting the mesh sizing coarser!

But I then have other question.

I set the iteration to 750, but it stopped at #685. Although I can still visualize the result, the Setup Tasks showed white, I couldn't click it anymore. It seemed that the simulation haven't finished. Does anyone know why?

Thank you!

[Jon.Wilde]

Did you add all of the CFD exe's to both firewall and antivirus?

[Anonymous]

Hi all,

I had the same problem, but you can see in Solve window, the 'Solve' button changed to 'Stop', I think it means the simulation have some problems (maybe divergence) so it can not run anymore.

Correct me if I am wrong, 

Thank you.

[Amal.C]

Hi @Anonymous,

Thanks for reaching out!

May I ask if you can open a new thread where you better explain the problem you are currently having?

I appreciate your time.

Many thanks,

Amal