[Fasouras]

Good evening

i have a problem with my results in ansys fluent as i get the cl at 8 deegree aoa
(which i have set through boundary conditions ) at a e.t.c 1.004*10-2 which ofc is extremely low. My domain is water. I have attached pictures of the mesh. I have done the same analysis at a 2d hydrofoil naca0012 and the results were something like 0.6, 0.8 which were ok according to papers. I have used standard k-epsilon.

My question is if the problem is in DM in MESH or in FLUENT Setup.

Thanks very much in advance

(if you need other pictures i can provide them )

[Turi_Giuliano]

Hello, could you tell me what kind of solver do you use? Did you checked Y+ value? And what range of vecity do you use? Does there appear compression Mach>0,3? What with residuals, does they run good?

Your mesh looks quiet complicated, a lot of elements in the nearest envoirment of foil.
I recomend you to check Orthogonal Quality and Aspect ratio, if they are in good limits.

Last time for hydrofoil with 8m/s velocity i used something like attached.
https://ibb.co/cAjo80

With Y+ in range 20-70, Model k-E Relizablem EWT. And there is corelation between 3D , 2D and wind tunel test.

Also, why do you mesh also foil solid?

[Fasouras]

Originally Posted by Turi_Giuliano

Hello, could you tell me what kind of solver do you use? Did you checked Y+ value? And what range of vecity do you use? Does there appear compression Mach>0,3? What with residuals, does they run good?

Your mesh looks quiet complicated, a lot of elements in the nearest envoirment of foil.
I recomend you to check Orthogonal Quality and Aspect ratio, if they are in good limits.

Last time for hydrofoil with 8m/s velocity i used something like attached.
https://ibb.co/cAjo80

With Y+ in range 20-70, Model k-E Relizablem EWT. And there is corelation between 3D , 2D and wind tunel test.

Also, why do you mesh also foil solid?

hi sir and thanks for the reply

what do you mean what solver do i use?you mean the model? or the programm? also i have read in other posts too about the Y+ values etc but i am not quite familiar as for what this is exactly... what is it and how is it affect my results?

also i have set foil to solid and the surrounding area as fluid

is that wrong?

[Turi_Giuliano]

Originally Posted by Fasouras

hi sir and thanks for the reply

what do you mean what solver do i use?you mean the model? or the programm? also i have read in other posts too about the Y+ values etc but i am not quite familiar as for what this is exactly... what is it and how is it affect my results?

also i have set foil to solid and the surrounding area as fluid

is that wrong?

Hello I mean model.
Y+ should be good fitted to given model and physics, there is many online calculators to setup this parameter on meshing stage (just put in google Y+ calculator). The Y+ says about boundary layer thickness and it depends on model. I recomed you to get know, there is good explanation: https://www.youtube.com/watch?v=5bMYaIRHXlM

And to simulate flow around foil you need only model and mesh fluid domain. It means that you do not need to model and mesh foil.

[Fasouras]

Originally Posted by Turi_Giuliano

Hello I mean model.
Y+ should be good fitted to given model and physics, there is many online calculators to setup this parameter on meshing stage (just put in google Y+ calculator). The Y+ says about boundary layer thickness and it depends on model. I recomed you to get know, there is good explanation: https://www.youtube.com/watch?v=5bMYaIRHXlM

And to simulate flow around foil you need only model and mesh fluid domain. It means that you do not need to model and mesh foil.

Hi again and sincerely thanks for your answers

i will watch the video for sure but as i understand the y+ is determeined from the ansys from the inflation layers?

Also you mean i dont need to mesh the airfoil? but i want the cl and cd to be calculated there..i dont think not meshing it is an option..actually i have added mapped mesh on the surface of it, and in general i have added patch conforming method..

Thank you very much in advance sir !!

[Turi_Giuliano]

Originally Posted by Fasouras

Hi again and sincerely thanks for your answers

i will watch the video for sure but as i understand the y+ is determeined from the ansys from the inflation layers?

Also you mean i dont need to mesh the airfoil? but i want the cl and cd to be calculated there..i dont think not meshing it is an option..actually i have added mapped mesh on the surface of it, and in general i have added patch conforming method..

Thank you very much in advance sir !!

Exactly, you dont need mesh solid because you computing domain is fluid ith removed foil shape.