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October 19, 2018, 11:01 |
Low results in CL and CD at a 3d naca0012
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#1 |
New Member
Greece
Join Date: May 2017
Posts: 20
Rep Power: 9 |
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 ) |
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October 21, 2018, 03:05 |
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#2 |
New Member
Arek
Join Date: Jan 2017
Posts: 4
Rep Power: 9 |
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? |
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October 24, 2018, 12:43 |
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#3 | |
New Member
Greece
Join Date: May 2017
Posts: 20
Rep Power: 9 |
Quote:
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? |
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October 28, 2018, 02:40 |
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#4 | |
New Member
Arek
Join Date: Jan 2017
Posts: 4
Rep Power: 9 |
Quote:
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. |
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October 28, 2018, 08:52 |
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#5 | |
New Member
Greece
Join Date: May 2017
Posts: 20
Rep Power: 9 |
Quote:
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 !! |
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October 29, 2018, 15:01 |
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#6 | |
New Member
Arek
Join Date: Jan 2017
Posts: 4
Rep Power: 9 |
Quote:
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