Calculate Normals based on Initial Particles?


So I am trying to do something which I think might be out of the scope of the current DualSPHysics capabilities. Basically I have a sinus sloped profile as such:

And I want to use the new Modified Dynamic Boundary Condition (MDBC) to simulate. The problem is that when I run the simulation I get the warning:


1. The selected DDT '(Fourtakas et al 2019 (full)' needs several boundary layers when h/dp>1.5

2. There are 7162 of 8071 fixed or moving boundary particles without normal data.

Where I dont understand the first warning, but it always pops up, but the 2nd one is what I am dealing with right now, since I was hoping there might be a way for me to easily upload normal data for my sloped profile? My sloped profile has a "width" of 2 particles:

But maybe I should have more particles also in the width? I hope someone can help me out.

Kind regards


  • Okay I kept working on it and now I have gotten it to work and calculated normals:

    This is done by making a bi4 file, overwriting position values in bi4 to match the sine curve exactly and then use the new "Surface normal generator" tool. The problem is that when I run the simulation using MDBC now I see the unphysical gap..

    This doesn't make sense to me since I can confirm from Paraview (using "3D Glyph"-> "Arrow" -> "Orient" -> "Normals") that my normals behave correctly as shown in first picture. If I use a regular distribution of particles and use MDBC I see:

    Which shows that there is no gap - so that works. I cannot figure out why it would not work with what I did though, since I am using the surface normal tool to generate a .nbi4 file, then adding this .nbi4 to my original simulation and then I confirm that normals are correct ( see first picture again) and points towards fluid..

    Can anyone show me an example of how to use "SurfaceNormals -casefile Wedge3d -surface isosurface.vtk -savevtk normals.vtk" (example from code help) correctly?

    Kind regards

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