In addition to AVEtec's extensive thermodynamic models of the vortex process, AVEtec also continues to develop CFD models. OpenFOAM CFD software is used to model and optimize the process.
Several of the OpenFOAM buoyant compressible flow solvers are used to model the process including bouyantPimpleFoam and bouyantBoussinesqPimpleFoam. The following screenshot shows typical velocity streamlines as the vortex rises from the arena:
University of Western Ontario
With support from the Government of Ontario, Canada, under the Ontario Centres of Excellence (OCE) research-to-commercialization program, AVEtec Energy Corporation and the University of Western Ontario (UWO) - Boundary Layer Wind Tunnel Laboratory (BLWTL) carried out a Computational Fluid Dynamics (CFD) study of the AVE process in 2007. The CFD study was done by graduate student Natarajan Diwakar under the supervision of Professor Horia Hangan.
The size and scale of the model used in the CFD studies was selected to replicate results from a small scale experimental model. Various parameter studies were completed to determine optimum AVE design geometry and process parameters.The results of the CFD study were published in January 2011 as chapter 5 of Diwakar Natarajan's PhD thesis. Chapter 5 of thesis - Simulation of Atmospheric Vortex Engine
The UWO CFD study concluded that:
The CFD analysis of a model-scale Atmospheric Vortex Engine (AVE) was performed. The results show that the AVE can generate a vortex flow in the atmosphere much above the AVE and the vortex acts as a physical chimney limiting the mixing of surrounding air into the raising plume of hot air. A parametric study was conducted and provides a good starting point for future designs. For a given geometry, the physical parameter ΔT (temperature difference between the inlet air to AVE and ambient air) is the main parameter that controls the strength of the vortex and in turn the power output. The full scale simulations subjected to cross wind show that the power generation capacity is not affected by the cross winds.
AVEtec comments on CFD study report:
The simulation was done with CFD program FLUENT. The problem definition and geometry were well done. Initial results using the FLUENT "laminar flow" option looked like physical model results. FLUENT has several turbulence options one of which is "k-e turbulence". Based on Raleigh Number the mode of simulation was switched from "laminar flow" to "k-e turbulence". The results of the "k-e turbulence" did not look like the physical model results. Selecting the "k-e turbulence option" forces the flow to be turbulent.
The AVEtec position is that giving the air rotation about the vertical axis causes the air to spin. As a result turbulence is inhibited because when a particle of air moves inwards its tangential velocity increases to conserve angular momentum, resulting in an increase in centripetal force which pushes the air particle back outwards. As a result the flow in the vortex is laminar instead of turbulent as evidenced by the smooth thread shape in waterspouts and in the physical model. Centrifugal force stabilizes the flow thereby reducing turbulence, frictional losses and mixing.A photograph of the experimental model and sample CFD results for domain heights of 2 m and 6 m are shown below.
Sample CFD results for 2 m domain height (Temperature, Tangential Velocity):
Sample CFD results for 6 m domain height (Temperature, Tangential Velocity):