Newtonian Poiseuille flow in ducts of annular-sector cross-sections with Navier slip

We consider the Newtonian Poiseuille flow in a duct the cross section of which is either a circular or an annular sector assuming that Navier slip occurs either along both the cylindrical walls or only along the outer cylindrical wall. A general analytical solution is derived and the results for the latter case are discussed and the effects of the angle of the sector, the radii ratio and the slip number are analysed.