Hey everyone!! I am working on improving natural draft counter flow cooling tower efficiency as my final year B.E. project. I came across a research paper that said that at transverse cross section of the tower, above drift eliminators, the air velocity decreases from the periphery to the middle of the tower, while the temperature increases. The statement is also supported by CFD simulation of the tower. If viscosity effect is considered, the velocity at the periphery of the cross section of the tower should be less than that at the center. I am assuming that since the flow of air takes place from the edges of the tower at the bottom, the velocity must be progressively reducing as air approaches towards the center of the tower, than at the periphery. Is this assumption acceptable? Also, could the hyperbolic shape of the tower have got anything to do with the influence on air velocity profile across tower section?