JetBoard Drag Coefficient + Planning Effects

Using SimScale Fluid Flow / CFD
1

Hi,

I am trying to simulate a surfboard (for all intents and purposes) that I have model in CAD, operating and design point of 32 mph (~14 m/s). I am trying to determine the drag coeff. of the board.

I am new to CFD as well as vessel hydrodynamics. I followed the airplane wing SimScale tutorial, and adjusted settings as necessary to setup a CFD for the board.

I have some questions however.

Q1) Aside from the inlet wall and the outlet wall of the flow region, all other wall surfaces should be slip conditions as described in the airplane wing tutorial. Would this apply to the the top surface (water surface) of the flow regime as well?

Q2) The board will be planning at design point. How might I take that into effect when running the CFD. Since this will effect both the angle of the board relative to the water surface, as well as the surface area of the board in contact with the water. (This question might be outside the scope of SimScale forum)

Q3) assuming the above questions are sorted and I have got the CFD working properly, how would I then obtain the drag coefficient of the board, as well as the total drag force on the board in SimScale.

Any help regarding this would be very much appreciated. Thanks!

Here is a link to the CFD project, the geometry of the board is already included, as well as a second geometry that the CFD was run on.

2

Hi @jshakar,

Thanks for posting your question!

A1) Yes, slip condition should be applied to the water surface too.

A2) I’m not sure if I got this question correctly, but with a multiphase flow analysis it would be possible to simulate this interface board-water being affected to this relative angle. However multiphase is not available for community accounts.

A3) The drag coefficient will be outputted as a plot in the solutions, as shown down below. Furthermore you can find more detailed informations about it in this article.

Screen Shot 2023-07-07 at 10.11.02
Screen Shot 2023-07-07 at 10.11.021617×929 124 KB

best,

3

Thank you for getting back to me. I will be back to CFD once I have the axial impeller sizing done (working on a Electric Jet Board) and can create a model for further testing.