# Simulate trees in wind study
**URL:** https://www.simscale.com/forum/t/simulate-trees-in-wind-study/86893
**Category:** Using SimScale
**Created:** [November 17, 2019, 9:28am UTC](https://www.simscale.com/forum/t/simulate-trees-in-wind-study/86893 "2019-11-17T09:28:43Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@sholz](https://www.simscale.com/forum/u/sholz)
#### Post date: [November 17, 2019, 9:28am UTC](https://www.simscale.com/forum/t/simulate-trees-in-wind-study/86893/1 "2019-11-17T09:28:43Z")
Hy everybody,
I am doing a windstudy in urban context with trees. So far I am setting trees as no slip walls. However, as trees aren’t solid objects, I was wondering if there is the possibility to use a specific porosity model for trees, in order to simulate the wind passing through trees?
Many thanks in advance!
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### Author:  [@jousefm](https://www.simscale.com/forum/u/jousefm)
#### Post date: [November 17, 2019, 11:06am UTC](https://www.simscale.com/forum/t/simulate-trees-in-wind-study/86893/2 "2019-11-17T11:06:14Z")
Nice project idea with the trees @sholz!
I have answered this some time ago in this post: **[CFD simulation/ dust distribution at pedestrian level - #2 by jousefm](https://www.simscale.com/forum/t/cfd-simulation-dust-distribution-at-pedestrian-level/86094/2)**
Let me know if that helped!
Jousef
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### Author:  [@sholz](https://www.simscale.com/forum/u/sholz)
#### Post date: [November 17, 2019, 11:34am UTC](https://www.simscale.com/forum/t/simulate-trees-in-wind-study/86893/3 "2019-11-17T11:34:41Z")
Hi Jousef,
thank you for the equation, this helps! Whould I set P in Boundary Condition \> costum?
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### Author:  [@jousefm](https://www.simscale.com/forum/u/jousefm)
#### Post date: [November 17, 2019, 12:11pm UTC](https://www.simscale.com/forum/t/simulate-trees-in-wind-study/86893/4 "2019-11-17T12:11:21Z")
If you need more advanced settings you can use the custom BC in case the standard ones do not offer this advanced options you are looking for. Do you work on a validation from a paper?
Best,
Jousef
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### Author:  [@sholz](https://www.simscale.com/forum/u/sholz)
#### Post date: [November 17, 2019, 1:48pm UTC](https://www.simscale.com/forum/t/simulate-trees-in-wind-study/86893/5 "2019-11-17T13:48:58Z")
I am working on a wind study in urban context. As there are many trees in the area, I think the influence of trees are quite important.
I checked the standart boundary conditions for fluid dynamics Velocity inlet, Pressure inlet, Velocity outlet, Pressure outlet, Wall, Periodic, Symmetry, Wedge) and didnot find the possibility to define define the porosity.
Am I locking at the wrong place?
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### Author:  [@Retsam](https://www.simscale.com/forum/u/Retsam)
#### Post date: [November 17, 2019, 9:14pm UTC](https://www.simscale.com/forum/t/simulate-trees-in-wind-study/86893/6 "2019-11-17T21:14:12Z")
@sholz: Please try Advanced concepts \> Porous media