[CFD] Turbulence Intensity for RANS

This talk discusses the different reference velocities that can be used in the definition of Turbulence Intensity, and the effect that this choice has on the computed values in RANS CFD.

Time stamps
0:00 Introduction
0:51 Background
2:49 Typical Values
4:20 How to calculate Turbulence Intensity
8:01 Turbulence Intensity for RANS
14:18 Reference Velocity
15:33 Example Problem
19:51 Summary of reference velocity choice
20:59 Contour labels
22:04 Check your CFD code!
23:11 Velocity-inlets
26:53 Summary
27:57 Outro

References
CFD Online, 'Turbulence Intensity', Accessed October 2022

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Disclaimer
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The methods, algorithms, equations, formulae, diagrams and explanations in this talk are for educational and demonstrative purposes only. They should never be used to analyse, design, accredit or validate real scientific / engineering / mathematical structures and flow systems. For such applications, appropriate trained, qualified and accredited (SQEP) engineers / scientists should be consulted along with the appropriate documentation, procedures and engineering standards. Furthermore, the information contained within this talk has not been verified, peer reviewed or checked in any way and is likely to contain several errors. It is therefore not appropriate to use this talk itself (or any of the algorithms, equations, formulae, diagrams and explanations contained within this talk) as an academic or technical reference. The reader should consult the original references and follow the verification and validation processes adopted by your company / institution when carrying out engineering calculations and analyses. Fluid Mechanics 101 and Dr. Aidan Wimshurst are not accountable or liable in any form for the use or misuse of the information contained in this talk beyond the specific educational and demonstrative purposes for which it was intended.

[ethanjohnson]

Babe wake up, there’s a new Fluid Mechanics 101 video.

[opencast]

Great wrap-up! Even to me a CFD engineer with 25 years in the field it gave great tips for the results visualization! Thank you Aidan, will apply that.

[jessbuildstech]

Really excited to listen to this! Finally some helpful information on YouTube for CFD!

[nerfthis]

After finishing many of your previous videos, I got an A in my CFD course. I will definitely donate to you if my life gets richer in the future!

[NanoActuator]

It was a requirement since little information was available on the internet and was not clear enough. I think you will complete uncovering every piece of important concepts in CFD in the future. Thanks.

[nrc]

Excellent and simple breakdown of the term with its physical meaning, to the point! Thanks Dr. Aidan

[hungnguyenthanh]

Thanks very much doctor Aidan. Thank to you, I am capable of improving and enhancing my knowlegdes about CFD. I can apply these informations in my researchs and workings much more. You are really genius 😀😀😀

[whatnonsense]

You are doing awesome work, your channel helped me alot understanding concepts

[botonbeg]

That's just a masterpiece. Thank you!

[АндрейМартынов-ес]

Thank you so much for very useful content!

[sneakyninja]

Great video as always, could you do a video on Hybrid models say differences between DES DDES and IDDES?

[dongdongdong]

Very good presentation. Can you also talk about turbulence viscosity.

[李佳忆-ec]

If I make a contour of turbulence intensity in Fluent, the contour typically use the reference velocity which is defined in the Reference Data Settings Page. But if I want the turbulence intensity based on the local velocity, the typical turbulence intensity in Fluent should be treated as a constant. And after that, multiply it with the velocity magnitude.

[SO-dlpv]

Excellent as usual!
In 5:10 the 6th item in the list: "Sum and take the square root". Isn't 'sum' redundant since in step 5 the mean of x, y, and z components is calculated?

[ramongalvich]

I literally googled this topic, when you released this video. Thanks!

[mariarosales]

Good day dr. Aidan, from silide 4:25, the step 5 would be a recall to also solve (u'_y ^2) and (u'_z' ^2) as steps 1 to 4 solved (u'_x ^2), right? or is this step 5 an extra mean value to be computed over (u'_x^2) solved in step 4?

[digguscience]

It seems that for the RANS model you have to use CFD software

[TurboAcki]

Nice Video. Is it smart to use thisto adapt the mesh size? Or what di I miss?

[vreijs]

If I look at an ABL flow (6.44m/sec @10m and z0=1m) I see at 12.5m height;, a speed |U| of 7.2m/sec and a KTE of around 1.6m2/sec2. And this gives an I
So your boundaries (1 and 5%) do not really work for an ABL environment. Do I misunderstand? Thanks for the feedback.

[scugglebottom]

Great content as always.

I've never understood the pro/con of this same intuition when applied to Pressure&Temperature boundary conditions where the options exist to use TKE & ESP or Length Scale & Viscosity Ratio.

Is there a reason you should employ one strategy over another when applied to a URANS sim for example?