Controlled Multi-Scale Turbulence through the Use of Laser Sintered Sierpinski Pyramids

The research presented here is the result of a new collaboration between the Centre for Advanced Additive Manufacturing (AdAM) and the Thermofluids group at The University of Sheffield, regarding the use of fractal geometries for the control and influence of fluid flow. It is believed that the use of multiscale objects can be used to introduce many different orders of turbulence into a flow. However, whilst substantial simulations have been carried out in this area, the complexity of the physical geometries means that to date these have not been validated via physical testing. In this work, varying orders of Sierpinski pyramids were produced using Laser Sintered PA2200 and analysed in a wind tunnel with regards to their effects on air flow through the structures. As predicted by theoretical analyses, the coarsest pyramids induced large vortices into the air-stream, whereas the more complex orders induced vortices at a number of different scales, rapidly developing into a standard turbulent flow. Further investigations are planned to isolate the effects of the smaller-scale turbulence in this situation.