I have site with some buildings for design I made cladding model for all of them then I run wind simulation .
The problem is the site is big and I just want to consider all the obstruction effects and how RSA deal with it
The wind profile it reach up to 950 m and the maximum height of my buildings is 15m and the loads come with almost wind zero pressure even the wind speed is 50 m / s.
the load is much more less than estimated
Model is attached .
My assumption is that the automatically generated wind tunnel is of such size that the generated mesh elements are too large comparing to the dimensions of the 'buildings/tents' which causes inaccurate wind pressure values on them.
Hi Mustafa,
I wanted to update you with the results of the investigation of the results obtained for this model:
The wind tunnel size is optimized for typical design situations in RSA (a single building rather than number of them being scattered over the large area) and to avoid issues with lack of convergence of the simulation within the reasonable time the height of the tunnel is assumed as at least 0.5*min (its width or its length).
If for your model you force it to be 0.1*min (its width or its length) then you will get the following results:
If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.
I believe that it should be possible to change the height of wind profile considered on the simulation. I had noticed that when you have big model in horizontal direction (low rise building ) and due to the height considered in wind tunnel which is much bigger than the building height the problem starts to occur in convergence and results will have errors.
I do agree for you that the options such as wind tunnel geometry and e.g. possibility of using smaller elements for better accuracy would be nice to have (I personally would vote for them) but they are currently not available to be set. On the other hand I do know that having them available would also cause a lot of issues when set incorrectly.
If I understand you correctly mean that Wind simulation is not considering the flow obstruction (which is could have different impact on building )
I believe also this is weak point in this wind simulation tool.
The code is considering this issue. and even Wind tunnel test. though the tools give strange results in complex geometry .
The Wind simulation is a nice tool But it cant replace the code do to its limitations + the time consuming of modeling the building cladding just for applying wind on it .
The option of applying wind load as per the code parameters on building Should be adopted in RSA . (it was Adopted in CBS and was working perfectly with applying the wind load on Slab edge )
Its totally unfair For company like Autodesk to cancel software with adopting its Technics on another one .
Save Our RSA.
If I understand you correctly mean that Wind simulation is not considering the flow obstruction (which is could have different impact on building )
I believe also this is weak point in this wind simulation tool.
No, it does consider them. The point is the size of the tunnel vs. the size of volumetric elements used for its meshing. As both are generated automatically then depending how you view this it is either the 'wind tunnel' being too 'large' for the number of generated mesh elements so thay are too large comparing to the size of elements of the model or there are too little mesh elements generated to give exact results. In other words what is needed is the control over either or both of them from the level of the user interface which is not possible now 
I'd also love to see some of the functionalities of CBS in Robot myself.
Sorry I didnt understand . Could you please explain it more.
And how Wind simulation consider the obstruction and is not modeled.
I understood the word obstruction as e.g. a building behind another one or a number of buildings in a group. Then if you create them as 'boxes' their influence on the wind load on the actually designed structure will be considered as the part of CFD analysis.
If you meant something else then I need some additional details to understand what you meant better.
Yes that what I mean by obstructions. Mean that wind simulation tools in RSA is not capable to do this issue ?
So how Can I check this effects on RSA .
If you noticed the case in RSA is going to be like you have building without any surrounding building and the wind flow on it this is very far from the existing case .
in Additional there is no other tool in RSA to generate the wind as per the code to compare the result of wind simulation with is it.
Its all to be done by manual calculation .
Check all structural software in the market all of them have option to generate the wind based on code .
The lesser accuracy of the results can be seen for a situation like in your model being low buildings with large (in comparison to their height) horizontal size of the area substructures are located (the reason being that the automatically generated wind tunnel is too high for the number of generated mesh elements which makes their sizes not matching with sizes of these low buildings). This should not be the case for a group of 'typical' multi-story buildings.
As I already wrote few times I'm happy to help (within the range of my knowledge) with the use of the program as it is but for what is missing or should be done in RSA part I can only forward your comments to the development team. Thank you for your understanding.
Many thanks to you my friend, we appreciate your assessment and answering us .
In our Side as RSA lover we always highlight all the missing issues and required new features not only for you to read it , its also to be checked from the development team and to develop it if so .
