How to refine a surface when you have to mesh on both sides of the surface
 

(New to OpenFoam) I am working on simulating a concentric-tube heat exchanger. Now since this requires multi-region meshing, I have planned to mesh the complete region first then divide it into 3 regions using topoSet. But I want to refine the surface of the pipe (which is in between the outer fluid and inner fluid).
Now to refine the surface of the pipe if I use the stl surface file of the pipe then I am not able to do the complete meshing (because if the point locationInMesh lies in the inner fluid then only the inner part gets meshed and if it lies in the outer fluid then only the outer gets meshed)
So my question is how do I refine the surface of the pipe and do the complete meshing at the same time?
Please suggest tutorials as well for whatever solution you suggest as this is my first project on OpenFoam
Thank you in advance.

This is how my geometry looks like (side-view) (let me know if you need any more information) (P: InnerFluid, Q: Pipe, R: OuterFluid)
https://www.learnpick.in/userfiles/a...1510556954.png

Several approaches:

• Use multi-region meshing (ESI-OpenCFD Version)
• Mesh each region separately
• Use your approach and split it into the single regions and apply another snappy step onto the fluid regions to get layers
• Use blockMesh and define single blocks (1/4 is sufficient) and mesh it as you would like to have it. Afterwards (if you are not using symmetry) you can revolve it to 360 °
• Alternatively you can use a wedge for the simulation rather than the whole geometry (if applicable)