SimScale CAE Forum

Pedestrian Wind Comfort Analysis


#21

Ooops, I take that back…

Your geometry bounding box diagonal is only ~1m… That is a less than lilliputian size city :wink:

Looks to me like it was drawn at mm scale, so likely scaling it by 1000 will have you going again…


#22

Alright, so if I scale it by 1000 and apply the same things I did before to the mesh, it should be working?


#23

Only if 1000 is correct, I only surmised that ratio…


#24

Meshing log is here now. Is there a problem here?

Now it’s this:


#25

Looking OK, we will see…


#26

Alright. Approximately how long should this take?


#27

You never know until you do 1st one… especially with the new ‘auto’ # of processors…


#28

Likely 1st time through was making the unlayered mesh, second time through was adding the layering…

EDIT: And since I never use enclosures, I missed that those extra runs had to do with double meshing all the buildings that were left in the geometry since ‘keep existing parts’ was checked when you made your enclosure, live and learn :wink:


#29

Ok, I’ll just wait and hope it works…


#30

It has been over 150 minutes… Here’s what the meshing log looks like.


#31

Hey @NLim8

I took a peek at your project. You’re facing these issues because your enclosure was made with “keep existing parts” on. When this option is enabled, all the solids (buildings) in your geometry will be kept and meshed. This approach is used for conjugate heat transfer and is not necessary for incompressible, external flows. Resulting meshes are quite big and take longer to run.

I copied your project, re-made the enclosure (with “keep existing parts” off) and ran the automatic hex dominant mesher and it does work as it should:

/Ric


#32

Thanks for your help! The original mesh (with “keep existing parts” on) finished generating after 356 mins. I wouldn’t really want to scrap it, but would that mesh affect the results of the simulation?



Link: https://www.simscale.com/projects/NLim8/pedestrian_comfort_analysis_in_financial_district_revised/

Since the keep existing parts is on for that mesh, is this why the simulation isn’t working?


#33

Yes, just redo as Ric did, his only used 3.2 core hours in 6 realtime minutes and ~450000 cells were made :wink:

Like I said, I don’t use enclosures so I missed the error Ric found, sorry.

In those 6 hours your mesh took last night, there were 31 million cells created…


#34

I changed the enclosure, but now the mesh can’t generate? I put it on very coarse though.


#35

@NLim8: You cannot expect to finish your mesh with such high refinement… (Region, mainly). Look at your log file from meshing:

Edge intersection testing:
Number of edges : 33997919
Number of edges to retest : 27538260
Number of intersected edges : 2410007

This is still run on 16 cores, but you will exhaust the memory anyway…

Stop that meshing, please and do the first, simple one, letting perhaps the surface refinement on buildings.

But you have to observe the meshing log and see if you are not trying to nuke the fly…

Cheers,

Retsam


#36

Thanks for your help! The mesh has completed generating. I’m not really sure what happened to my simulation, why aren’t I seeing the different colours?


#37

Would I have to redo the simulation, is there something I didn’t add?


#38

Hi @NLim8 !

If there’s something in the result control items for instance or another BC that you missed, you have to redo the simulation, yes!

For the Stream Tracer, have you used the PICK operation to choose where your streamlines start?

Best,

Jousef


#39

Time: 0.0000? It means that the visualization show status before simulation start. Please move to the simulation end (>>|).


#40

I used the pick operation, but it just seems like there’s too much blue. Also, how would I make it so that the ground has all the different colours, and that the buildings appear shaded in?