Document Type
Article
Publication Date
2-18-2020
Abstract
We present results from direct numerical simulations on laminar and turbulent non-canonical thermals with an initial rectangular density distribution at a Reynolds number of Re = 500 and Re = 5000, respectively. We find the non-canonical shape to induce strong azimuthal variations in the thermal for both the laminar and turbulent cases. These include noticeable differences in downward and horizontal propagation speeds as well as differences in the strength of the vortex tube. These differences persist over a significant period of time and help generate a cross-flow component that is otherwise not present in canonical cases. The cross-flow component is in the opposite direction to that observed in gravity currents with the same initial density distribution. This is counterintuitive seeing that both flows are solely driven by buoyancy. By extracting the three-dimensional streamlines, we find the descending vortex tube to force the dense fluid to follow a helical path.
Recommended Citation
Liu, Kai, N. Zgheib, and S. Balachandar. "On the spreading of non-canonical thermals from direct numerical simulations." Physics of Fluids 32.2 (2020): 026602. https://doi.org/10.1063/1.5138981
Publication Title
Physics of Fluids
DOI
10.1063/1.5138981
Comments
© 2020 Author(s). Original published version available at https://doi.org/10.1063/1.5138981