Extracting foil piercing angle at the free surface

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9 views24 hours agoDynamics simulations

Edoardo14 1 day ago 0 Comments

I’m looking for a way to show or calculate the piercing angle of a foil relative to the water surface within the ventilation module.

Specifically, I need to visualise the intersection angle between the foil geometry and the free surface interface.

Thanks.

Edoardo Asked question 1 day ago

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score 0 · Answer 1 · 2026-01-23T09:24:45+00:00

To show the piercing angle, first you need to set nearOceanFrame: true for the specific elements you want to analyse. This ensures the angle is calculated at the submerged element closest to the water surface.

Assuming a T-foil configuration with a vertical Shaft and two horizontal surfaces WingOB & WingIB:

"Elements": {
  "Shaft" : { "Mesh": { "Spanwise": { "nSeg": 20 } } },
  "WingOB": { nearOceanFrame: true, "Mesh": { "Spanwise": { "nSeg": 10 } } },
  "WingIB": { nearOceanFrame: true, "Mesh": { "Spanwise": { "nSeg": 10 } } },
},

We must manually alias the output frames from the Foil block. The Frame Graphics system requires names to end with the “Frame” suffix to render correctly; however, since multiple outputs from a single block cannot share that suffix without causing a display conflict, a separate copy is required for each.

In Blocks.Boat:

"WingIBFrame" : {
  "Frame" : BL.FrameXfromParent({
    ParentFrame : "{^.Foil.Hydro.Frame_WingIB_NearOcean}",
    Translation : [0,0,0]  
  }),
},

The piercing angle can then be calculated and converted into degrees:

"WingIBAngle" : "aLimit180({WingIBFrame.Frame}.eulerInFrame({Root.InertialFrame})[0]/pi*180)",

The same is done for the other horizontal surface:

R.merge("Blocks.Boat", {
  "WingOBFrame" : {
    "Frame" : BL.FrameXfromParent({
      ParentFrame : "{^.Foil.Hydro.Frame_WingOB_NearOcean}",
      Translation : [0,0,0]  
    }),
  },
  "WingOBAngle" : "aLimit180({WingOBFrame.Frame}.eulerInFrame({Root.InertialFrame})[0]/pi*180)",
});