Hello,

I have been carrying out an ANSYS Fluent CFD analysis of the system outlined in this paper: Article The solar cyclone: A solar chimney for harvesting atmospheric water

Broadly speaking, my results are as expected for the setup and I'm very happy with them. However, I am missing one crucial aspect; the cyclone cooling effect shown in Fig. 6 is not observed in my results. I'm confused as to why this is the case. The air accelerates and swirls as expected. I have tried modelling the air using the Boussinesq approximation, as an ideal gas and as a real gas but the issue persists. Perhaps I'm not fully grasping the mechanism causing this cooling.

I'm not 100% sure the boundary conditions I set up are correct. Both the inlet and outlet are pressure boundaries with 0Pa gauge pressure. The inlet is at 300K and the backflow from the outlet is at 288K. I wasn't sure if I should set the gauge pressure for the outlet to a negative value to account for the change in pressure with altitude, or if the system deals with this. The solar flux is modelled by using the inbuilt solar loading and works as expected creating a temperature rise across the collector. Even velocities of the updraft are of the correct order according to quick calculations. I'm a bit lost as to where I have gone wrong, any help would be appreciated.