Water sticking to surface of hull in waves when y+=1

cagriaydin · December 21, 2021, 06:09

Hey all,

I have a problem with boat-in-waves type of simulation. As can be seen from the video, when y+ values are close to 1, some of the water from waves sticks to the bow of the hull and stays like that. Doesn't happen with the same conditions when wall functions are used with coarser first cell height (y+>30). Anyone has had a problem like this before?

(y+=1)

(y+>30)

(Higher resolution)
https://gfycat.com/rawzanyaffenpinscher
https://gfycat.com/jitteryamusedcoelacanth

Peresvet · December 21, 2021, 07:01

https://www.researchgate.net/post/Y_setting_in_Star_CCM

It depends on your choice of turbulence closure. If you choose the k-epsilon turbulence model with a wall function near the wall, y + should be between 30 and 150. However, if you are using Spallart-Allmaras turbulence closure or k-omega, you should use y + close to 1. Since these two models should work for a viscous sub-layer.

cagriaydin · December 21, 2021, 09:52

Quote:

Originally Posted by Peresvet

https://www.researchgate.net/post/Y_setting_in_Star_CCM

It depends on your choice of turbulence closure. If you choose the k-epsilon turbulence model with a wall function near the wall, y + should be between 30 and 150. However, if you are using Spallart-Allmaras turbulence closure or k-omega, you should use y + close to 1. Since these two models should work for a viscous sub-layer.

Thanks for your reply. However, y+=1 case is already k-w SST turbulence model and the other one is k-epsilon. I will try to increase the inner iteration count since maybe VOF solver or turbulence viscosity having a hard time converging in a time-step.

Peresvet · December 21, 2021, 20:44

Let me ask you. Why did you choose this way of solving the problem? Why are you not satisfied with the standard solution that allows you to solve problems in automatic mode? Are you not satisfied with an error of less than 0.1% ?! I am working on version 16.06.
Thank you for your reply.

December 21, 2021, 06:09	Water sticking to surface of hull in waves when y+=1	#1
cagriaydin New Member Çağrı Join Date: Feb 2015 Posts: 11 Rep Power: 11	Hey all, I have a problem with boat-in-waves type of simulation. As can be seen from the video, when y+ values are close to 1, some of the water from waves sticks to the bow of the hull and stays like that. Doesn't happen with the same conditions when wall functions are used with coarser first cell height (y+>30). Anyone has had a problem like this before? (y+=1) (y+>30) (Higher resolution) https://gfycat.com/rawzanyaffenpinscher https://gfycat.com/jitteryamusedcoelacanth Last edited by cagriaydin; December 21, 2021 at 10:03. Reason: more obvious gifs

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December 21, 2021, 07:01		#2
Peresvet Member Peresvet Join Date: Mar 2021 Location: USSR Posts: 51 Rep Power: 5	https://www.researchgate.net/post/Y_setting_in_Star_CCM It depends on your choice of turbulence closure. If you choose the k-epsilon turbulence model with a wall function near the wall, y + should be between 30 and 150. However, if you are using Spallart-Allmaras turbulence closure or k-omega, you should use y + close to 1. Since these two models should work for a viscous sub-layer.

December 21, 2021, 20:44		#4
Peresvet Member Peresvet Join Date: Mar 2021 Location: USSR Posts: 51 Rep Power: 5	Let me ask you. Why did you choose this way of solving the problem? Why are you not satisfied with the standard solution that allows you to solve problems in automatic mode? Are you not satisfied with an error of less than 0.1% ?! I am working on version 16.06. Thank you for your reply.