AI Article Synopsis
- Dissolving small amounts of polymer in a Newtonian fluid can significantly alter how that fluid flows, especially in transitional and turbulent states.
- High-speed imaging techniques reveal complex behaviors in submerged jets of these polymer solutions as they enter calm Newtonian fluids.
- A new transitional pathway to elastoinertial turbulence is identified, characterized by unique shear-layer instabilities producing polymer filaments, with a consistent frequency decay pattern observed across varying conditions.
Article Abstract
Dissolving small amounts of polymer into a Newtonian fluid can dramatically change the dynamics of transitional and turbulent flows. We investigate the spatiotemporal dynamics of a submerged jet of dilute polymer solution entering a quiescent bath of Newtonian fluid. High-speed digital Schlieren imaging is used to quantify the evolution of Lagrangian features in the jet revealing a rich sequence of transitional and turbulent states. At high levels of viscoelasticity, we identify a new distinct transitional pathway to elastoinertial turbulence (EIT) that does not feature the conventional turbulent bursts and instead proceeds via a shear-layer instability that produces elongated filaments of polymer due to the nonlinear effects of viscoelasticity. Even though the pathways to the EIT state can be different, and within EIT the spatial details of the turbulent structures vary systematically with polymer microstructure and concentration, there is a universality in the power-law spectral decay of EIT with frequency, f^{-3}, independent of fluid rheology and flow parameters.
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| http://dx.doi.org/10.1103/PhysRevLett.127.074501 | DOI Listing |
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