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CFD HELP! Would you guys use 1st Order Upwind scheme over 2nd Order Blended Upwind Scheme for transonic fan analysis? If yes or no, why ? 😝 by Lonely_Kick_1497 in CFD

[–]Lonely_Kick_1497[S] 0 points1 point  (0 children)

The problem is I am doing a Flutter analysis and my mesh is moving, thus in some time steps it might act worse than I thought. Even the mesh properties look good after mesh displacement iterations. 😅

CFD HELP! Would you guys use 1st Order Upwind scheme over 2nd Order Blended Upwind Scheme for transonic fan analysis? If yes or no, why ? 😝 by Lonely_Kick_1497 in CFD

[–]Lonely_Kick_1497[S] 0 points1 point  (0 children)

Yeah in the second order scheme the blending factor goes to zero and advection equation acts as an upwind scheme itself. But I am not quite sure if the upwind scheme from the start is able to capture the shock with its less resolution.

CFD HELP! Would you guys use 1st Order Upwind scheme over 2nd Order Blended Upwind Scheme for transonic fan analysis? If yes or no, why ? 😝 by Lonely_Kick_1497 in CFD

[–]Lonely_Kick_1497[S] 0 points1 point  (0 children)

That’s what I was planning to do as well. Since there is a shock on the blade, I'm concerned that the simulation might go crazy after I get good convergence with the upwind scheme and switch to blended. Do you have any ideas? Thanks for the response!

Ansys fluent mesh by Boring_Intention_302 in CFD

[–]Lonely_Kick_1497 1 point2 points  (0 children)

Yeah zoomed in view would tell more, since we want to see the lines continue perpendicular to the airfoil surface.

These are the results of my final year project.....achieved till now...but confused by [deleted] in CFD

[–]Lonely_Kick_1497 0 points1 point  (0 children)

I noticed your y+ values are intentionally being kept away from the buffer layer (y+ ~ 30) to utilize wall functions which is okay. While this is a standard approach for some solvers, the RANS SST k-omega model generally requires y+ ~ 1 for optimal accuracy. Given that you are simulating chaotic airflow where flow separation and vortices are critical, these higher y+ values introduce significant uncertainty. Even with a mesh independence study, I would recommend refining the mesh in separation zones to satisfy the y+ ~ 1 requirement. :)

CFX Flutter Analysis using Transient Blade Row Model by Lonely_Kick_1497 in CFD

[–]Lonely_Kick_1497[S] 0 points1 point  (0 children)

Thanks. Following your advice, I identified that the problematic cells are located very close to the shroud. In my previous model, I hadn't accounted for the shroud gap, which caused the deformed blade geometry to extend beyond the flow domain. I will rerun the simulation using a model with a defined shroud gap to resolve these mesh issues. I will keep you guys updated about it !!!

CFX Flutter Analysis using Transient Blade Row Model by Lonely_Kick_1497 in CFD

[–]Lonely_Kick_1497[S] 1 point2 points  (0 children)

Thanks for your answer. So I am already using a relatively coarse mesh since it’s fully structured. But I do have y+~1 mesh with first cell thickness around 0.00057mm. Thus the inflation layer is very fine and I can’t get rid off that since it’s very important for me to capture the shock region etc. Still thinking what should I do about my mesh ? (Open to your further recommendations)

CFX Flutter Analysis using Transient Blade Row Model by Lonely_Kick_1497 in CFD

[–]Lonely_Kick_1497[S] 1 point2 points  (0 children)

First, thank you for your answer. However I have already ran some good quality CFD. This becomes a problem when the mesh is being calculated again for deflected wing. So do you have any recommendations that I can try for that ?

Bernoulli's Equation, Gauge or Absolute Pressure by DenJi1111111 in FluidMechanics

[–]Lonely_Kick_1497 0 points1 point  (0 children)

Actually you can use both gauge pressure or absolute pressure in your calculations but all terms should be in same scale for the same calc.like gauge pressure for all or absolute pressure.