broken cfd mesh

[Koaib Kaleem]

hi,

i dont know why but after every time i run the cfd mesh my stl file is broken, i thought initially that my two stacks (x-z symmetry activated) that i have made as nozzles interesct eachother and that could be the reson so i coverted them to cedit and have adjusted the crossections so they dont touch eachother but still the same broken result. same thing can be seen in vspaero analysis, the distribution comes out to be unsymmetric.
can anyone kindly guide what could be the reason?

[Koaib Kaleem]

one point to add is that the stl file i not broken if i directly export it to stl from openvsp, problem happens when cfd mesh is generated 

any guidance will be appreciated, thx