# \[Inflate boundary layer - Refinement\] - Critical problem **URL:** \ **Category:** Project Support\ **Created:** [December 17, 2017, 12:30pm UTC](https://www.simscale.com/forum/t/inflate-boundary-layer-refinement-critical-problem/81282 "2017-12-17T12:30:24Z")\ **Posts on this page:** 1\ **Showing post:** 5
**Author:** ![Get\_Barried](https://www.simscale.com/forum/user_avatar/www.simscale.com/get_barried/32/20599_2.png) [@Get\_Barried](https://www.simscale.com/forum/u/Get_Barried)\ **Post date:** [December 18, 2017, 12:04pm UTC](https://www.simscale.com/forum/t/inflate-boundary-layer-refinement-critical-problem/81282/5 "2017-12-18T12:04:13Z")
Hi @Jackie_U! Yes I have tried the mesh clip but I haven’t been able to obtain what I need. Its probably like you said, the increased number of cells just cause the mesh clip not work properly for some reason. I will attempt to mesh it out for you on my end to see if I can figure this out and will let you know if I have gotten anything. I don’t see why setting the boundary layer inflation does not produce the desired results but you did have a good guess that the surface refinements somehow overlap the boundary layer inflation and this might actually be the case. We’ll take things one step at a time. > [@Jackie\_U](#): > > Regarding the .STL issue, I will follow your piece of advice. Could you recommend me an appropriate offline CAD software for the face splitting? I would like to divide my rear wing into 6 surfaces (2 endplates + 4 planes/flaps), so I need to perform the splitting and then join some of the resulting surfaces. Well unfortunately I have not done face splitting before in an offline CAD software. Referring to this [post](https://www.simscale.com/forum/t/how-to-split-an-stl-geometry-into-different-faces/8276/7) you can use either SolidWorks or as previously mentioned OnShape where you can perform the face splitting. Definitely assembling it is the proper way to go instead of splitting each individual piece one by one. Also if you read the link, the proper file format is STP not STL apparently so maybe try converting it to STP then upload it here and see if you can perform the splitting operation on SimScale. Let me know how it goes! Regards, Barry --- _[View the full topic](https://www.simscale.com/forum/t/inflate-boundary-layer-refinement-critical-problem/81282)._