topic Re: Turbulence Intensity problem in CFD Forum

Turbulence Intensity problem

Anonymous — Fri, 10 May 2019 13:52:16 GMT

Hello,
I'm looking to find a solution, for the more than 1 (100%) turbulence intensity inside the room.
How have to setting the turbululence parameters, that inside the room the turbulence intensity values be under 100% or some place, maybe a little more, because of the calculation fault?
The first picture, show the turbulence intesity. In the red zone, the intensity more than 1.
In the second picture we can see, the a 0.15 m/s velocity (iso surface).

Thanks for anybody help.

MARK

Re: Turbulence Intensity problem

frederic.gaillard.7 — Fri, 10 May 2019 14:32:27 GMT

Hello

turbulence intensity is only a parameter to caracterize the flow. Check the exact formula here.
You have the opportunity to change the turbulence intensity in the Advanced Turbulence Parameters but i will not recommend to change this value, currently setted to 0.05, specially for you type of simulation.
Fred

Re: Turbulence Intensity problem

Anonymous — Sat, 11 May 2019 16:27:58 GMT

Thank you for your reply. In the Standard the turbulence intensity average value is determined. For tangential air conduction systems about 40-60%. How can I reach that for the room?

MARK

Re: Turbulence Intensity problem

frederic.gaillard.7 — Mon, 13 May 2019 13:51:15 GMT

What is you Standard?

Can you attach a piece of documentation where you find your values of 0.4-0.6.

Re: Turbulence Intensity problem

Anonymous — Thu, 16 May 2019 13:16:46 GMT

In the ISO 7730.

Re: Turbulence Intensity problem

Anonymous — Thu, 16 May 2019 13:39:35 GMT

Here is what autodesk say about Turbulence Intensity

Why dont you try a simulation at 5% and another one at 40% ?

Re: Turbulence Intensity problem

Anonymous — Thu, 16 May 2019 13:46:18 GMT

I've tried already, but it wasn't show major difference. By the way, that applies for the inlet, but the 40% in the standard it's concern for the all room.

Re: Turbulence Intensity problem

frederic.gaillard.7 — Thu, 16 May 2019 14:17:34 GMT

Hello @Anonymous ,

Are you sure that the definition of turbulence intensity of the iso norm are the same as the turbulence intensity of a RANS turbulence model ? The parameter used in a thermal comfort studies might be different that the one adopted in fluid mecanics.

Fred