3D Boundary Layer Mesh Problems - Coronary Vessel
I am trying to mesh the volume which corresponds to a coronary artery and is enclosed by three STL files. The target it to mesh the volume using around 400.000 high order elements in order to run CFD simulations for a project. I am very thankfull to Professor Geuzaine for helping me with the tolerance problem a week ago. The issue I have been facing now and I have been stuck in the past week is related first to the boundary layer. I am aware that a general solution to three dimensional boundary layers is not available at the moment and I have been trying to generate one (consisting of three layers for a start, with the relative thicknesses stated in the geo file) using extrusions as seen on the sphere tutorial. I am using gmsh GUI from Windows 10 as I am new to the program and unfortunately have no experience on Python.
When I try to generate the 3D Mesh and use the clipping option the inner part of the volume looks like the following image: I would like to ask how can the mesh elements of the main volume not interfere with the elements of the boundary layer?
A second problem I am facing is when I try to remesh the volume in 3D, after making a modification (to the element size for example) when I receive the error : Could not find extruded vertex. In this case no mesh is generated.
Finally some of the tatrahedra elements have very bad quality as it can be seen from the images above. This could be related to Meshlab which I used to fill the holes as I received the geometry with open holes and the size I have used on Gmsh. In case this creates important issues and no option from the Mesh Settings help to reach the target number of elements I have other solutions in mind like remeshing on Meshlab or Blender.
Thank you very much for your assistance,
P.S. As it is my second issue on a specific project should I reopen the closed issue and attach this as a follow up?