[CFD] The Spalart-Allmaras Turbulence Model 

I cannot express how much of a service this is to the world, I'm doing a PhD and these videos are literally saving my ass. I come back and watch these videos over again every so often, every time I learn and understand a little more, every time I feel a sense of relief when the penny drops. Thank you so much.

I have been digging through papers for the last week or so and this explanation was very well laid out and could have saved me a lot of time on coming up to speed. Really really really well done!!! You are asset to the new folk in the CFD community, dont stop!!!

All, I can say is "I FOUND YOU, NuTILDA". This video has answered most of the questions with which i've been struggling far too long . Probably the most concise video on SA turbulence model on RU-vid. Couple of questions: 1) How would they have measured Turbulent Kinematic Viscosity experimentally , to obtain that profile? 2) When we speak about diffusion terms in the Momentum equation, What is getting diffused ? (Velocity?) How is diffusion related to viscosity? and how do we relate viscosity to concentration gradient intuitively ? 3) Can you differentiate how the SA Curvature Correction model is different from the Standard SA model? From , my experience the SA curvature correction model provides a much better correlation at higher AoA (i.e separation dominated flows), I would like to understand , why? Finally , thank you soo much for this one. P.S (Watching it on replay)

I used to be super confused with the value nuTilda in OpenFOAM. Thank you so much for the explanation!

I think 'S' in the production term in the S-A model is the magnitude of vorticity which is related to the rotation tensor instead of the shear-rate tensor. Correct me if I am wrong. Thanks

just fantastic!!!!! easy way to learn

Good lecture.

A FANTASTIC VIDEO! I finally start to understand some of the concepts. Thank you so much!

I have no words to describe how happy I am to have watched this video. Thank you a lot man. You could describe whats I have looking in just simple words that make me understand and increment my wish to keep going to the CFD world. Thank you a lot.

Hey buddy...big fan of your videos...would you mind doing a video on the LES and DES models as it is commonly used in CFD simulations...would really appreciate it..:)

Thank you for the very comprehensible explanation. One remark: comparing with my old cfd lecture manuscript, isnt there a c_mu missing in front of the right-hand expression in (25) ?

For practical use, I understand SA is only applicable in exterior aerodynamics, and even there is less accurate that k-w SST. The only advantage it has is that it is computationally cheaper?

Awsome video! Very clear and informative.

Hey...could u make a lecture video on Moving Reference Frame method!

As usual, concise yet precise, crystal clear presentation! Great job

Please do a video on LES/DES models

Thank you! Very clear and informative =)

thank you so much! you're explainations are the best. it is helping in understanding CFD a lot. never stop making videos. 👍👌😊

All that you have explained is quite lucid and informative. It gives a good overview to understand what actually happens when we use this model!

Great video! By the way, is it possible for you to make a lecture video on dealing with the pressure boundaries (Prgh and/or P), in both incompressible and compressible solvers? It should be very helpful to understand how OpenFOAM handles the term before choosing the Boundary/Initial conditions provided by OpenFOAM, like prgh, p, prghTotalHydrostaticPressure, prghTotalPressure, prghPressure, and many more out there. I know there are many discussions on the subject on the cfd online or other forums, but a comprehensive introduction is still absent. Anyone interested in this, please let me know. Thanks in advance.

best

Isn't it for external flow in the main aerofoils etc

Thx

Nice episode. Could you please give a little more explanation about why nut is proportional to (y+)^4 in the viscous sublayer ?

Wao! Great Job. Thanks for sharing.

hi Dr.Aidan Thnak you for sharing this wonderful vedio. Could you please answer a stupid question from me. What happened if we apply Multiple reference Frame.?Which velocity are we going to use in Spalart-Allmaras transport equation? My opinion is to use a relative velocity in the LHS and all absoulte Velocity in the Rhs( production term,dissipate term and diffusion term).

I was wondering that there might be a typo in the momentum equation. abla \dot \tau = abla \dot ((\mu+\mu_t)(( ablaU)+( ablaU)^T)) + abla \dot (-2/3\mu( abla \dot U)I) = abla \dot ((\mu+\mu_t)(( ablaU)+( ablaU)^T)) + abla(-2/3\mu( abla \dot U)). Correct me if I am wrong. Thanks.

Great video, thanks! A question I had is: Why do you say that u_t = \tilde u f_{v1} has "quartic behavior"? It appears as (linear)*(cubic)/(cubic+C), which I am not sure how this is quartic?

Hi Aidan, Just wondering where are the turbulent kinetic energy and other 2/3 term in the Reynolds averaged equation? Since they were present at the begging of k-epsilon model video. Waiting for your reply.

I was waiting for this! Thank you.

Splendid as usual. Excellent explanation

Good job bro congratulations

Fantastic! Can‘t wait to see more about turbulence modeling...maybe v2-f or reynolds-stress models? 😉👌

Great talk, thanks so much. Can you make a video about the Rotational corrections applied to the SA turb model (SA-RC) to capture streamline curvature in RANS simulations?

Thank you very much, that was very helpful, keep it up!

Thank you for the concise explanation. I am doing some work that requires me to understand this model and reading the original paper is sometimes. At least now I can read it with a clearer idea.

Hello! thank you for your explanation. :D I've tried to run SA model in an airfoil with C-domain (structured mesh) I got y^+ below 1 but I couldn't get good results in Cd coefficient. I've tried to solve a flow of Re = 7e5 (Transitional) in OpenFOAM... I think that this Reynolds number isn't compatible with OpenFOAM's SA model formulation. What I mean is the SA model hasn't a transitional model incorporated. In numbers I've could get results with a difference around 5% and 10 % in Cl and Cm coefficients in relation to experiment, but a difference of 60% in Cd. Could you give me your opinion of what happens whit this? Best regards!

Thanks for the awesome videos! Are the slides that you use free available?

Hi Aidan sir, I think equation 8 is not correct. should we not use del . (-2/3 meu.....)????? in equation 8

Ausome job

Stupid question: In the momentum equations there should also be a term related to the Boussinesq approximation, namely -2/3 k delta_ij, right? If so, how can we find the turbulent kinetic energy k from nu_tilde? Could we also find the dissipation epsilon? Thank you for your help Aidan:)

These videos are great !!!!

Is S-A model suitable for rotor stator interaction under MRF and under Sliding mesh.

Thanks Dr.Aidan

Hi, nice videos, solved many doubts about basics of CFD. I have one request/suggestion. You should also make videos on complete simulation of few standard problems. For example, I am working on vortex shedding about circular cylinder in a rectangular duct( 300 mm wide and 25 mm depth). I can found videos on the basics or the shallow simulations. But no videos are there that explain simulation of shedding phenomena using correct fundamentals of CFD and Fluid Mechanics. Please make a video on vortex shedding , Reynolds number 3000-15000 considering all basic details correctly. It will help a lot in practice/implementation of fundamentals.