Model border in Spaces

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abcd
Posts: 22
Joined: Wed Jun 03, 2020 11:43 am

Model border in Spaces

Post by abcd »

I'm studying a zone of 500 x 500 m2, with a resolution of 2 x 2 m2. So, I obtained a 250*250 grids. As I know, the area should be three times bigger. So I put 750 grids (250*3). But the model inspector says: " very little space between buildings and model border" (see attached). My questions are:
1- What is the advantage of using a grid much larger than the study area?
2- How much grids should I put in order to cancel the red message in the model inspector?
3- As you can see in the second figure attached, all empty patches are added to the right and at the top of the study area. How can I center the buildings in the grid?
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Question.PNG
question envi 2.PNG

Tim
Posts: 1707
Joined: Mon May 15, 2017 3:46 pm

Re: Model border in Spaces

Post by Tim »

Hi,

I would not say that it always needs to be 3 times bigger. Just make sure that maybe 1 block-width of buildings is added on each side which is not needed in your study results (so that they can be cut away in the output maps). What you did now is adding a lot of open space which is not necessary.
3 ways are now possible:
1. If starting from scratch in Spaces: Leave the space at the borders free from the beginning on.
2. If you digitized the model by hand in Spaces, still have the raw version without the open space at the top and right of the model area and the model is not Full3D (DetailedDesign): Go to tools and choose the tool "Add empty cells at border" and add some (maybe 5-7) on each side.
3. If you exported it from Monde (what I think and hope as well): Simply export the model area again with a larger subarea (including some areas slightly outside of your area of interest) and click on More Options shortly before. There you are able to add empty cells before the export process starts (also 5-7 cells).

Best regards,
Tim

abcd
Posts: 22
Joined: Wed Jun 03, 2020 11:43 am

Re: Model border in Spaces

Post by abcd »

Hi Tim,

Thank's for your advise. This worked very well. :D
Now for the vertical extension:
- Should the area be at least three times as high as the highest building ( as mentioned in the tutorial: getting started: Part 5/7) ? If yes, could you explain to me please why?
- Do I have to apply the same method of the horizontal one (add few cells : Tools -->add empty cells at border), or from ( model & settings --> Edit settings --> Model Geometry --> model
dimensions: Z-grids )

Thank you for your support.

Tim
Posts: 1707
Joined: Mon May 15, 2017 3:46 pm

Re: Model border in Spaces

Post by Tim »

Hi,

Yes, it is needed to have open space above buildings to avoid turbulence at the model area top. Wind flow is disturbed by the buildings and space at the top is needed that the wind flow can be stabilized again. Otherwise it is pressed downwards and the whole simulation gets instable.
I would not use the Add empty cells tool for that. The second suggestions using Edit settings is the correct way to do that.

Best regards,
Tim

abcd
Posts: 22
Joined: Wed Jun 03, 2020 11:43 am

Re: Model border in Spaces

Post by abcd »

Hi Tim,
Thank you so much for all of your help. :)

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