# Base Overturning moments and pressure coefficients

Hi there,
I am currently working on project as part of my university degree. I am trying to investigate the aerodynamic benefits of adding a tapered helical form to the CAARC building.

For this i am hoping to investigate the base overturning moments and the pressure coefficients at 2/3 of the building height. If possible could someone provide me with some advice on how i can set these calculation up in Sim Scale. I believe i have the base overturning moment force correct? I am not sure however, on how to set up a way for a pressure measurement at 2/3H on both the windward face and leeward face.

Side note: Any help on what value to normalise all the coefficients (Base overturning moment coefficient and pressure coefficient) would be brilliant!

Any help would be really useful and appreciated.

Sam

Hi Sam,
i hoped you had a great start to the new year.
please have a look at this post I covers a lot of analysis about a free-standing building.

You can also find a valiudation case on a CAARC building in which you can find information about the setup here:

I hope that this can give you a good start. please let us know if that helps.

Best regards
Sebastian

Hi Sebastian,

I took a read of the post you made and it was very insightful and is a shame i am un able to replicate this fully due to my account restrictions.

I do have one question, In a paper i am looking at the author mentions that the base overturning moments are normalised using the following formula.

If I wanted to use this to normalise the figures in my results how would i insert the number found from this formula. Is this possible or would i need to use the given input page.

Sam

Hi great that I could help.

In regards to your question would set the values as follows.

U = free stream velocity.

H*D = refreance Area
H = height of the building = reference length

please make sure that the pitch axis for the building is at the base of the building.

Best regards Sebastian

Thank you for the help with this, when using these inputs what formula is used to normalise the values obtained?
Is the formula the same as that used in the research paper i mentioned or does simscale use an alternative formula?

Thanks

Sam

Hi the moment coefficient is defined as:

with c being the reference length.

Best regards Sebastian

brilliant, thank you for your help

Hi Sebastian,

I was just wondering if it would be possible for you to provide advice on my current model that I am working on. I am trying to study the effects of tapering and adding helical forms to the CAARC building.

I wish to assess the base overturning moments (coefficients), the total drag of the building and finally the pressure acting on the façade on all building faces.

If possible could you take a look through my model and advise on anything that needs to be changed or added please?
https://www.simscale.com/workbench/?pid=4228370608098992886&mi=spec%3A93fd962c-19b7-47b5-b97f-173e32e80f42%2Cservice%3ASIMULATION%2Cstrategy%3A93&ps=domain

Thanks

Sam

Hi Sam,
please have a look at this validation case and compare it with your results. I’m also sure that you can find some research papers to compare your results against before trying a new geometry.

Best regards
Sebastian