[CFD] The SIMPLE Algorithm (to solve incompressible Navier-Stokes)

Excelent. These videos are very very helpful. Thanks!

Before asking it is good video and thank you. Can you explain how simple algorithm can work in unsteady state? Or SIMPLE algorithm can not apply to unsteady flow case?

good work sir

What about Boundary conditions for velocity? Is that included in matrix M?

Hello sir , can you explain Rhie & Chow interpolation in your videos or would you advise any video that explain it?

Hi! Thank you very much for these videos. When will you explain "couple" algorithm?

Great work, Aidan! You've just got a new subscriber. Best regards from Rio de Janeiro, Brazil

could u plz explain on similar for compressible flow solutions?.. with OpenFOAM terms like in this one... i am tired of searching on literature where i couldnt get a clear idea on how to solve one..

Great video! I want to ask you if I use the SIMPLE algorithm in a transient case in Fluent and the time step is converging from the first iteration, does it affect the solution statistics like the moments? I forced the solver to do more than 1 iteration and the moment was changing quite a bit within each time step but I am not sure if the overall average is affected. (I am using LES dynamic Smagorinsky with the default residuals)
Thank you!

Hey Aidan!

I´ve seen the PRESTO! scheme for pressure coupling, does it relate to the SIMPLE algorithm?

Awesome video!

Thank you for your great work. Can you do a video about MAC algorithm too? It would be very useful for me as I'm doing a course on CFD this semester.

Amazing way of explaining things

Dr You are a great teacher. I would request you to please do a video on Artificial Compressibility Method for solving the NS equation. It would be a huge favor. TIA

Thanks Aidan for an extremely informative and succinct video.
A few clarifications if I may:
1. After step 1 in the solution process, do we use the new velocity field to compute H and A again before step 2?
2. After step 3, once we realize U does not satisfy momentum equation, do we compute H and A again before solving for pressure in Step 2?
Thank you.

What about the residuals Aidan?

The solver guess values for the flow variables and uses them on the transport and continuity equations. The residuals that we usually see in CFD software are the difference between those guessed values in the transport and continuity equation? In a way that for every cell in the mesh, there is a residual? so CFD software normalizes them using a specific method?

never understood this algorithm till i found your video. thank you so much. keep up the great work.

Hi! How do you solve the Poisson equation in matrix form for the pressure field (Eq. 22)? Is there an iterative procedure, or is it solved directly?

Very informative....thank you👍😊

Can you make a video on structured and unstructured grid🧐

Your videos are extremely helpful! I'm your CFD fan :D

So, after the first iteration we go back to momentum equation and use grad p from the first poisson equation like a guess and calculate U field again ?

Nice explanation. Quite clear to me as i have some previous basic knowledge. But for a beginner would be difficult to get.

You are the freaking man, I have yet to have a question involving CFD that you have not covered, and covered well! I'm undergraduate learning CFD for a research project I just got funding for and your videos have been a monumental benefit to me!

It was really helpful for me, thank you.

Remarkable explaination.
Can you help me develop own code for direct numerical simulation?

Quite convoluted explanation to simple algorithm probably because of learning coming from openfoam side.

i just want to know how to prove the converge of P.

Hi @Fluid Mechanics101 I have a question, suppose the time level you explained is nth level. when we go to n+1 time level, does the momentum equations is solved for velocity is based on pressure gradient evaluated from poisson equation in n th time level?

I see, this is the SIMPLE algorithm, not the simple algorithm

hi I have to use buoyant Boussinesq simple foam in open foam and my question is what is the difference in natural convection problems
best regards

Thanks for such an amazing lecture. I learned a lot about CFD and the fluid mechanics itself. I just have one question to ask you. you said convection term (u dot gradient) u is equal to gradient dot (uu) by product rule but isn't (u dot gradient) u equal to 2 times gradient dot (uu)?

What happens after step 3 when the momentum equation is left unsatisfied? Do we then make a guess for pressure again based on previous loop?

Awesome video! Thank you!

Congratulations for the best CFD channel I have seen. You not only do teach CFD, but also are a teaching model, clear and concise. Ansys Fluent´s black box becomes transparent thanks to your videos. Chapeau! and Thanks!

Fantastic content man!

Thank you very much for the video.
I have a quick question. I am trying to figure out the matrix M, however, there is the non-linear term that complicates things. Any ideas on how to overcome this? I get products of velocities and that can't be represented in the matrix-vector multiplication.
I was guessing we could use velocities from previous iterations but I don't know if that would work.
I am also using finite differences, I don't know if the problem does not show up when using FV instead.

Man, your work is amazing! Many thanks!

Hello professor, I have a question. For solving the NS equation, there is one algorithm which is an explicit predictor-corrector . What's that? And how to apply to the formulation? And if you don't mind, maybe make a video example also. Thanks

Thank you for the video

Thanks Aiden. Keep doing what you're doing brother. Much love <3

In what cases is SIMPLE algorithm recommended over it's counterparts such as SIMPLEC, COUPLED, PISO etc.?

Thank you for the incredibly helpful content on CFD principles! I've gained a lot from your explanations. Could you also cover the COUPLED algorithm in one of your future videos? I'd really appreciate your insights on this topic! Thanks again!

Damn, I really needed this video in 2017 fall semester lol

GREAT VIDEO!

Great lecture! ! Just feel a bit confused about Eq.23. Doesn't it come from Eq.21 which is momentum equation? Why do we say the velocity field is corrected to satisfy continuity instead of momentum equation?

If I have body forces (like gravity) the discertization will be MU=-gradP+g ? And If I have a situation that the density and dynamic viscosity change as a function of temperature, for example in a transient natural convection model, the continuity and N.S will be extended because the term drho/dt. The solution algorithm will be the same?. The SIMPLE algorithm can handle with that?
Thank you 😊

Hello,
I do not understand the step from equation 8 to 9. If you decompose M, H must also be multiplied with U?

What am I getting wrong?

Thanks in advance!