# CFD simulation/ dust distribution at pedestrian level

**URL:** <https://www.simscale.com/forum/t/cfd-simulation-dust-distribution-at-pedestrian-level/86094>\
**Category:** Project Support\
**Created:** [August 12, 2019, 7:57pm UTC](https://www.simscale.com/forum/t/cfd-simulation-dust-distribution-at-pedestrian-level/86094 "2019-08-12T19:57:37Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![jousefm](https://www.simscale.com/forum/user_avatar/www.simscale.com/jousefm/32/34908_2.png) [@jousefm](https://www.simscale.com/forum/u/jousefm)\
**Post date:** [August 12, 2019, 9:22pm UTC](https://www.simscale.com/forum/t/cfd-simulation-dust-distribution-at-pedestrian-level/86094/2 "2019-08-12T21:22:54Z")

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Hi @Mo_Elsebaei - very nice project idea! 🙂

1. Sounds good but it depends if you want to see transient structural behavior on the buildings or is steady-steate fine for you? Did you already decide? For the turbulence model maybe @1318980 or @ananthu_ajit can comment as I have not tested k-omega SST myself, all I know is that k-epsilon underpredicts in the strong wind and wake regions, maybe they can comment on that.

2. Maybe this approach here helps you: **[Passive Scalar Sources](https://www.simscale.com/docs/content/simulation/model/advancedConcepts/passivescalarSources/passivescalarSources.html)** - for the calculation of the concentration of dust you could use the approach from @tcakir here: **[Pollution exhaust in a garage - #4 by tcakir](https://www.simscale.com/forum/t/pollution-exhaust-in-a-garage/85652/4)**

3. You can define the porosity ( P ) of a (coniferous) tree by

P = 1-\frac{Dc}{4\*(LAI/h)}

where

- LAI = Leaf Area Index (LAI)
- Dc = Needle diameter
- h = Height of the canopy

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1. Not if you want to use the approach mentioned in 2) I would say as you need the calculator filter which is not yet implemented (but on the roadmap)

Hope I could help you a bit!

Jousef

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**Relevant articles:** Pekin, B.; Macfarlane, C. Measurement of Crown Cover and Leaf Area Index Using Digital Cover Photography and Its Application to Remote Sensing. _Remote Sens._ **2009** , _1_ , 1298-1320.doi:[10.3390/rs1041298](http://dx.doi.org/10.3390/rs1041298)

**Source for the porosity calculation:** [Porosity of Trees -- CFD Online Discussion Forums](https://www.cfd-online.com/Forums/main/13996-porosity-trees.html)

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